{"id":75927,"date":"2026-02-13T14:26:23","date_gmt":"2026-02-13T06:26:23","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/75927.html"},"modified":"2026-02-13T14:26:23","modified_gmt":"2026-02-13T06:26:23","slug":"jvm-12-oom%e5%ae%9e%e6%88%98%e5%85%a8%e8%a7%a3%ef%bc%9a7%e7%a7%8d%e6%ba%a2%e5%87%ba%e5%a4%8d%e7%8e%b0%e3%80%81mat%e5%ae%9a%e4%bd%8d%e3%80%81%e4%bb%a3%e7%a0%81%e4%bf%ae%e5%a4%8d%e4%b8%8e%e7%94%9f","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/75927.html","title":{"rendered":"JVM--12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09"},"content":{"rendered":"

OOM \u5b9e\u6218\u5168\u89e3：7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5（\u4e0b）<\/h2>\n

\u4f5c\u8005：Weisian \u53d1\u5e03\u65f6\u95f4：2026\u5e742\u670813\u65e5<\/p>\n

\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

\n

\u4e00\u3001OOM\u8bca\u65ad\u524d\u7f6e\u51c6\u5907：\u73af\u5883\u4e0e\u5de5\u5177<\/h2>\n

1.1 \u73af\u5883\u57fa\u7840\u914d\u7f6e<\/h3>\n

1.1.1 \u8f6f\u786c\u4ef6\u73af\u5883\u8981\u6c42<\/h4>\n\n\u73af\u5883\u9879\u63a8\u8350\u914d\u7f6e\u517c\u5bb9\u6027\u8bf4\u660e<\/tr>\n\n\n\n\n
JDK\u7248\u672c<\/td>\nOracle JDK 8 \/ OpenJDK 11+<\/td>\nJDK 17\u9700\u5fae\u8c03\u5143\u7a7a\u95f4\u53c2\u6570，\u6838\u5fc3\u903b\u8f91\u901a\u7528<\/td>\n<\/tr>\n
IDE\u5de5\u5177<\/td>\nIntelliJ IDEA 2023+<\/td>\nIDEA\u5185\u7f6eMAT\u63d2\u4ef6，\u64cd\u4f5c\u66f4\u4fbf\u6377<\/td>\n<\/tr>\n
\u672c\u5730\u5185\u5b58<\/td>\n4GB\u4ee5\u4e0a\u53ef\u7528\u5185\u5b58<\/td>\n\u5806\u8f6c\u50a8\u5206\u6790\u9700\u5360\u7528\u5927\u91cf\u5185\u5b58，\u5efa\u8bae8GB+<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

1.1.2 \u751f\u4ea7\u7ea7JVM\u53c2\u6570\u6a21\u677f（\u76f4\u63a5\u590d\u7528）<\/h4>\n

java -Xms4g -Xmx4g \\\\<\/span>
\n # \u5143\u7a7a\u95f4\u914d\u7f6e（\u907f\u514d\u5143\u7a7a\u95f4\u6ea2\u51fa）<\/span>
\n -XX:MetaspaceSize=<\/span>256m \\\\<\/span>
\n -XX:MaxMetaspaceSize=<\/span>512m \\\\<\/span>
\n # OOM\u65f6\u81ea\u52a8\u751f\u6210\u5806\u8f6c\u50a8\u6587\u4ef6（\u6838\u5fc3\u6392\u969c\u4f9d\u636e）<\/span>
\n -XX:+HeapDumpOnOutOfMemoryError \\\\<\/span>
\n -XX:HeapDumpPath=<\/span>\/data\/logs\/heapdump-$(<\/span>date<\/span> +%Y%m%d)<\/span><\/span>.hprof \\\\<\/span>
\n # GC\u65e5\u5fd7\u914d\u7f6e（\u5206\u6790GC\u76f8\u5173OOM）<\/span>
\n -XX:+PrintGCDetails \\\\<\/span>
\n -XX:+PrintGCDateStamps \\\\<\/span>
\n -XX:+PrintGCTimeStamps \\\\<\/span>
\n -Xloggc:\/data\/logs\/gc-$(<\/span>date<\/span> +%Y%m%d)<\/span><\/span>.log \\\\<\/span>
\n -XX:+UseGCLogFileRotation \\\\<\/span>
\n -XX:NumberOfGCLogFiles=<\/span>5<\/span> \\\\<\/span>
\n -XX:GCLogFileSize=<\/span>100M \\\\<\/span>
\n # \u7981\u7528\u663e\u5f0fGC，\u907f\u514d\u5e72\u6270GC\u7b56\u7565<\/span>
\n -XX:+DisableExplicitGC \\\\<\/span>
\n -jar app.jar<\/p>\n

\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

\n

1.2 \u6838\u5fc3\u8bca\u65ad\u5de5\u5177\u5b89\u88c5\u4e0e\u9a8c\u8bc1<\/h3>\n

\u5728 Java \u5e94\u7528\u53d1\u751f OutOfMemoryError（OOM） \u540e，\u7cbe\u51c6\u5b9a\u4f4d\u5185\u5b58\u6cc4\u6f0f\u6839\u6e90\u662f\u5173\u952e\u3002\u672c\u8282\u4ecb\u7ecd\u4e09\u6b3e\u4e92\u8865\u7684\u6838\u5fc3\u8bca\u65ad\u5de5\u5177：<\/p>\n

    \n
  • MAT（Memory Analyzer Tool）：\u7528\u4e8e\u79bb\u7ebf\u6df1\u5ea6\u5206\u6790\u5806\u8f6c\u50a8\u6587\u4ef6（.hprof），\u9002\u5408\u751f\u4ea7\u73af\u5883\u4e8b\u540e\u590d\u76d8；<\/li>\n
  • Arthas：\u652f\u6301\u7ebf\u4e0a\u5b9e\u65f6\u8bca\u65ad，\u65e0\u9700\u91cd\u542f\u5e94\u7528，\u9002\u7528\u4e8e\u8fd0\u884c\u4e2d\u7cfb\u7edf\u7684\u5feb\u901f\u6392\u67e5；<\/li>\n
  • JConsole：JDK \u81ea\u5e26\u53ef\u89c6\u5316\u76d1\u63a7\u5de5\u5177，\u9002\u5408\u5f00\u53d1\/\u6d4b\u8bd5\u9636\u6bb5\u7684\u8d8b\u52bf\u89c2\u5bdf\u4e0e\u65e9\u671f\u9884\u8b66\u3002<\/li>\n<\/ul>\n

    \u4e09\u8005\u7ed3\u5408，\u53ef\u8986\u76d6\u201c\u4e8b\u524d\u76d1\u63a7 \u2192 \u4e8b\u4e2d\u8bca\u65ad \u2192 \u4e8b\u540e\u5206\u6790\u201d\u5168\u94fe\u8def\u3002<\/p>\n

    \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

    \n

    1.2.1 MAT（Memory Analyzer Tool）\u2014\u2014 \u5806\u8f6c\u50a8\u79bb\u7ebf\u5206\u6790\u5229\u5668<\/h4>\n

    \u4e0b\u8f7d\u4e0e\u914d\u7f6e（Windows）<\/h5>\n
      \n
    • \n

      \u4e0b\u8f7d\u5730\u5740： https:\/\/www.eclipse.org\/downloads\/download.php?file=\/mat\/1.16.1\/rcp\/MemoryAnalyzer-1.16.1.20250109-win32.win32.x86_64.zip<\/p>\n<\/li>\n

    • \n

      \u914d\u7f6e\u6587\u4ef6（MemoryAnalyzer.ini）\u5efa\u8bae\u4fee\u6539\u5982\u4e0b：<\/p>\n

      -startup
      \nplugins\/org.eclipse.equinox.launcher_1.6.900.v20240613-2009.jar
      \n–launcher.library
      \nplugins\/org.eclipse.equinox.launcher.win32.win32.x86_64_1.2.1100.v20240722-2106
      \n-vmargs
      \n–add-exports=java.base\/jdk.internal.org.objectweb.asm=ALL-UNNAMED
      \n-Xms2g
      \n-Xmx8g
      \n-XX:+UseG1GC
      \n-Dfile.encoding=UTF-8\n <\/li>\n<\/ul>\n

      \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

      \u8bf4\u660e：\u9002\u5f53\u8c03\u5927\u5806\u5185\u5b58（\u5982 -Xmx8g）\u53ef\u63d0\u5347\u5927\u6587\u4ef6\u89e3\u6790\u6027\u80fd\u3002<\/p>\n

      ，\u914d\u7f6e\u5b8c\u6210\u540e，\u53cc\u51fb MemoryAnalyzer.exe \u542f\u52a8\u5373\u53ef\u3002\u5982\u4e0b\u56fe：<\/p>\n

      \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

      \u6838\u5fc3\u7528\u9014<\/h5>\n
        \n
      • \u79bb\u7ebf\u5206\u6790 .hprof \u5806\u8f6c\u50a8\u6587\u4ef6；<\/li>\n
      • \u81ea\u52a8\u8bc6\u522b\u5185\u5b58\u6cc4\u6f0f\u5acc\u7591\u5bf9\u8c61；<\/li>\n
      • \u7cbe\u51c6\u5b9a\u4f4d GC Roots \u5f15\u7528\u94fe，\u63ed\u793a\u65e0\u6cd5\u56de\u6536\u7684\u6839\u672c\u539f\u56e0；<\/li>\n
      • \u7279\u522b\u9002\u7528\u4e8e\u751f\u4ea7\u73af\u5883 OOM \u4e8b\u6545\u7684\u4e8b\u540e\u6839\u56e0\u5206\u6790\u3002<\/li>\n<\/ul>\n
        \u5806\u6ea2\u51fa\u573a\u666f\u5b9e\u64cd\u6b65\u9aa4<\/h5>\n
      • \n

        \u83b7\u53d6\u5806\u8f6c\u50a8\u6587\u4ef6<\/p>\n

          \n
        • \u81ea\u52a8\u751f\u6210：\u901a\u8fc7 JVM \u53c2\u6570 -XX:+HeapDumpOnOutOfMemoryError \u89e6\u53d1；<\/li>\n
        • \u624b\u52a8\u751f\u6210：\u4f7f\u7528 jmap -dump:format=b,file=heap.hprof <pid>\u3002<\/li>\n<\/ul>\n<\/li>\n
        • \n

          \u5bfc\u5165\u5e76\u5206\u6790<\/p>\n

            \n
          • \u542f\u52a8 MAT \u2192 File > Open Heap Dump \u2192 \u9009\u62e9 heap.hprof；<\/li>\n
          • \u7b49\u5f85\u89e3\u6790\u5b8c\u6210（512MB \u6587\u4ef6\u7ea6\u9700 1\u20133 \u5206\u949f）\u3002<\/li>\n<\/ul>\n<\/li>\n
          • \n

            \u5feb\u901f\u8bc6\u522b\u6cc4\u6f0f\u5acc\u7591<\/p>\n

              \n
            • \u67e5\u770b\u5de6\u4fa7 Leak Suspects Report；<\/li>\n
            • MAT \u4f1a\u9ad8\u4eae\u663e\u793a\u5982 Problem Suspect 1，\u4f8b\u5982 java.util.ArrayList \u5360\u7528\u5927\u91cf\u5185\u5b58\u3002<\/li>\n<\/ul>\n<\/li>\n
            • \n

              \u6df1\u5165\u5b9a\u4f4d\u6839\u56e0<\/p>\n

                \n
              • \u5207\u6362\u81f3 Dominator Tree \u89c6\u56fe；<\/li>\n
              • \u6309 Retained Heap \u964d\u5e8f\u6392\u5e8f，\u627e\u5230\u5982 HeapOOM_StaticCollection.LEAK_CACHE；<\/li>\n
              • \u53f3\u952e\u8be5\u5bf9\u8c61 \u2192 Path to GC Roots \u2192 exclude weak references；<\/li>\n
              • \u82e5\u8def\u5f84\u7ec8\u70b9\u4e3a static \u5b57\u6bb5\u6216\u5355\u4f8b，\u5219\u786e\u8ba4\u4e3a\u5185\u5b58\u6cc4\u6f0f\u70b9\u3002<\/li>\n<\/ul>\n<\/li>\n
                \n

                1.2.2 Arthas \u2014\u2014 \u7ebf\u4e0a JVM \u5b9e\u65f6\u8bca\u65ad\u795e\u5668<\/h4>\n

                \u5feb\u901f\u5b89\u88c5（PowerShell \/ Bash）<\/h5>\n

                # \u4e0b\u8f7d<\/span>
                \ncurl<\/span> -O https:\/\/arthas.aliyun.com\/arthas-boot.jar<\/p>\n

                # \u542f\u52a8<\/span>
                \njava -jar arthas-boot.jar<\/p>\n

                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \u9009\u62e9\u4f60\u8981\u76d1\u63a7\u7684java\u8fdb\u7a0b，\u8f93\u5165\u5e8f\u53f7\u5373\u53ef\u3002 \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                \u6838\u5fc3\u7528\u9014<\/h5>\n
                  \n
                • \u65e0\u9700\u91cd\u542f\u76ee\u6807\u5e94\u7528；<\/li>\n
                • \u5b9e\u65f6\u76d1\u63a7\u5185\u5b58\u3001\u7ebf\u7a0b\u3001\u7c7b\u52a0\u8f7d\u7b49 JVM \u72b6\u6001；<\/li>\n
                • \u652f\u6301\u52a8\u6001\u6267\u884c\u8868\u8fbe\u5f0f\u3001\u751f\u6210\u5806\u5feb\u7167；<\/li>\n
                • \u9002\u7528\u4e8e\u751f\u4ea7\u73af\u5883 OOM \u7684\u5728\u7ebf\u5feb\u901f\u6392\u67e5\u3002<\/li>\n<\/ul>\n
                  Arthas \u589e\u5f3a\u7248\u547d\u4ee4\u901f\u67e5\u624b\u518c<\/h5>\n
                  1. \u7c7b\/\u7c7b\u52a0\u8f7d\u5668\u76f8\u5173\u547d\u4ee4<\/h6>\n\n\u547d\u4ee4\u4f5c\u7528\u8be6\u7ec6\u793a\u4f8b\u5e94\u7528\u573a\u666f<\/tr>\n\n\n\n\n\n\n
                  sc<\/td>\n\u67e5\u770bJVM\u5df2\u52a0\u8f7d\u7684\u7c7b\u4fe1\u606f<\/td>\nsc -d *UserService<\/td>\n\u67e5\u770b\u7c7b\u52a0\u8f7d\u4fe1\u606f\u3001\u7c7b\u52a0\u8f7d\u5668\u3001\u6ce8\u89e3\u7b49<\/td>\n<\/tr>\n
                  sm<\/td>\n\u67e5\u770b\u5df2\u52a0\u8f7d\u7c7b\u7684\u65b9\u6cd5\u4fe1\u606f<\/td>\nsm -d com.example.UserService *<\/td>\n\u67e5\u770b\u7c7b\u6240\u6709\u65b9\u6cd5\u7b7e\u540d<\/td>\n<\/tr>\n
                  jad<\/td>\n\u53cd\u7f16\u8bd1\u6307\u5b9a\u7c7b<\/td>\njad –source-only com.example.UserService<\/td>\n\u786e\u8ba4\u7ebf\u4e0a\u4ee3\u7801\u662f\u5426\u4e0e\u9884\u671f\u4e00\u81f4<\/td>\n<\/tr>\n
                  mc<\/td>\n\u5185\u5b58\u7f16\u8bd1\u5668，\u7f16\u8bd1.java\u6587\u4ef6<\/td>\nmc \/tmp\/UserService.java -d \/tmp\/output<\/td>\n\u7ebf\u4e0a\u7d27\u6025\u4fee\u590d，\u70ed\u66f4\u65b0\u4ee3\u7801<\/td>\n<\/tr>\n
                  redefine<\/td>\n\u52a0\u8f7d\u5916\u90e8.class\u6587\u4ef6，\u8986\u76d6\u539f\u7c7b<\/td>\nredefine \/tmp\/UserService.class<\/td>\n\u70ed\u66f4\u65b0\u4ee3\u7801（\u4e0d\u91cd\u542f\u5e94\u7528）<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
                  2. \u65b9\u6cd5\u8c03\u7528\u76d1\u63a7\u547d\u4ee4（\u6838\u5fc3\u529f\u80fd）<\/h6>\n\n\u547d\u4ee4\u4f5c\u7528\u8be6\u7ec6\u793a\u4f8b\u5e94\u7528\u573a\u666f<\/tr>\n\n\n\n\n\n\n
                  watch<\/td>\n\u76d1\u63a7\u65b9\u6cd5\u6267\u884c\u6570\u636e<\/td>\nwatch com.example.UserService getUser '{params,returnObj,throwExp}' -x 2<\/td>\n\u67e5\u770b\u65b9\u6cd5\u5165\u53c2\u3001\u8fd4\u56de\u503c\u3001\u5f02\u5e38<\/td>\n<\/tr>\n
                  trace<\/td>\n\u65b9\u6cd5\u5185\u90e8\u8c03\u7528\u8def\u5f84，\u8017\u65f6\u5206\u6790<\/td>\ntrace com.example.OrderService createOrder '#cost > 100'<\/td>\n\u6027\u80fd\u74f6\u9888\u5206\u6790（\u65b9\u6cd5\u8017\u65f6）<\/td>\n<\/tr>\n
                  stack<\/td>\n\u8f93\u51fa\u5f53\u524d\u65b9\u6cd5\u88ab\u8c03\u7528\u7684\u8c03\u7528\u8def\u5f84<\/td>\nstack com.example.PaymentService pay 'params[0]=="1001"'<\/td>\n\u67e5\u770b\u8c01\u8c03\u7528\u4e86\u8fd9\u4e2a\u65b9\u6cd5<\/td>\n<\/tr>\n
                  tt<\/td>\n\u65f6\u7a7a\u96a7\u9053，\u8bb0\u5f55\u65b9\u6cd5\u8c03\u7528\u6570\u636e<\/td>\ntt -t com.example.UserService login -n 5tt -i 1000 -p<\/td>\n\u53cd\u590d\u67e5\u770b\u5386\u53f2\u8c03\u7528\u8be6\u60c5<\/td>\n<\/tr>\n
                  monitor<\/td>\n\u65b9\u6cd5\u6267\u884c\u76d1\u63a7（\u7edf\u8ba1\u5468\u671f）<\/td>\nmonitor -c 10 com.example.OrderService createOrder<\/td>\n10\u79d2\u5185\u7edf\u8ba1\u65b9\u6cd5\u8c03\u7528\u6b21\u6570\u3001\u6210\u529f\u7387<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
                  3. \u53c2\u6570\u589e\u5f3a\u793a\u4f8b\u89e3\u6790<\/h6>\n

                  # 🔸 watch \u547d\u4ee4\u8be6\u89e3<\/span>
                  \nwatch<\/span> com.example.UserService getUser "{params,returnObj,throwExp}"<\/span> -x 3<\/span> -b -e -n 2<\/span><\/p>\n

                  # -x 3 : \u5c55\u5f00\u5bf9\u8c61\u6df1\u5ea6（3\u5c42）<\/span>
                  \n# -b : \u65b9\u6cd5\u8c03\u7528\u524d\u76d1\u63a7<\/span>
                  \n# -e : \u65b9\u6cd5\u5f02\u5e38\u540e\u76d1\u63a7<\/span>
                  \n# -n 2 : \u6267\u884c2\u6b21\u540e\u9000\u51fa<\/span>
                  \n# 'params[0]=="admin"' : \u6761\u4ef6\u8fc7\u6ee4（\u7528\u6237\u540d\u662fadmin\u65f6\u89e6\u53d1）<\/span><\/p>\n

                  # 🔸 trace \u547d\u4ee4\u8be6\u89e3<\/span>
                  \ntrace com.example.OrderService createOrder '#cost > 200'<\/span> -n 3<\/span> –skipJDKMethod false<\/span><\/p>\n

                  # '#cost > 200' : \u53ea\u663e\u793a\u8017\u65f6\u8d85\u8fc7200ms\u7684\u8c03\u7528<\/span>
                  \n# –skipJDKMethod false : \u663e\u793aJDK\u5185\u90e8\u65b9\u6cd5\u8c03\u7528（\u66f4\u8be6\u7ec6）<\/span><\/p>\n

                  4. JVM \u5185\u5b58\/\u7ebf\u7a0b\u6df1\u5ea6\u8bca\u65ad<\/h6>\n\n\u547d\u4ee4\u4f5c\u7528\u8be6\u7ec6\u793a\u4f8b\u5e94\u7528\u573a\u666f<\/tr>\n\n\n\n\n\n\n\n
                  memory<\/td>\n\u67e5\u770b\u5185\u5b58\u4f7f\u7528\u8be6\u60c5<\/td>\nmemory<\/td>\n\u5404\u5185\u5b58\u533a\u57df\u4f7f\u7528\u91cf（heap\/non-heap）<\/td>\n<\/tr>\n
                  gc<\/td>\n\u67e5\u770bGC\u4fe1\u606f<\/td>\ngc -i 2000<\/td>\n\u5b9e\u65f6GC\u6b21\u6570\u3001\u8017\u65f6<\/td>\n<\/tr>\n
                  thread<\/td>\n\u7ebf\u7a0b\u5206\u6790<\/td>\nthread -bthread –state BLOCKED<\/td>\n\u6b7b\u9501\u68c0\u6d4b\u67e5\u770b\u963b\u585e\u7ebf\u7a0b<\/td>\n<\/tr>\n
                  sysprop<\/td>\n\u67e5\u770b\/\u4fee\u6539\u7cfb\u7edf\u5c5e\u6027<\/td>\nsysprop user.countrysysprop user.timezone GMT+8<\/td>\n\u67e5\u770b\/\u4fee\u6539JVM\u7cfb\u7edf\u5c5e\u6027<\/td>\n<\/tr>\n
                  sysenv<\/td>\n\u67e5\u770b\u73af\u5883\u53d8\u91cf<\/td>\nsysenv JAVA_HOME<\/td>\n\u67e5\u770b\u7cfb\u7edf\u73af\u5883\u53d8\u91cf<\/td>\n<\/tr>\n
                  getstatic<\/td>\n\u67e5\u770b\u9759\u6001\u53d8\u91cf\u503c<\/td>\ngetstatic com.example.Config INIT_PARAM<\/td>\n\u5feb\u901f\u67e5\u770b\u914d\u7f6e\u503c<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
                  5. \u6392\u67e5 OOM \u5b9e\u6218\u547d\u4ee4\u7ec4\u5408<\/h6>\n

                  # 1\ufe0f\u20e3 \u8c01\u5360\u7528\u4e86\u5185\u5b58？（\u6309\u5bf9\u8c61\u7c7b\u578b\u5206\u7ec4）<\/span>
                  \nheapdump –live \/tmp\/live.hprof
                  \n# \u7136\u540e\u7528 MAT\/Eclipse Memory Analyzer \u5206\u6790<\/span><\/p>\n

                  # 2\ufe0f\u20e3 \u5b9e\u65f6\u67e5\u770b\u5927\u5bf9\u8c61<\/span>
                  \njvm |<\/span> grep<\/span> -E "G1|Old|Metaspace"<\/span>
                  \nmemory |<\/span> head<\/span> -20<\/p>\n

                  # 3\ufe0f\u20e3 \u54ea\u4e2a\u7ebf\u7a0b\u5bfc\u81f4 OOM？<\/span>
                  \nthread -n 10<\/span> -i 1000<\/span> # \u6700\u5fd9\u768410\u4e2a\u7ebf\u7a0b，\u6bcf\u79d2\u5237\u65b0<\/span><\/p>\n

                  # 4\ufe0f\u20e3 GC \u538b\u529b\u5927\u5417？<\/span>
                  \ngc -i 5000<\/span> # \u6bcf5\u79d2\u770bGC\u60c5\u51b5<\/span><\/p>\n

                  6. \u5176\u4ed6\u5b9e\u7528\u547d\u4ee4<\/h6>\n\n\u547d\u4ee4\u4f5c\u7528\u793a\u4f8b\u573a\u666f<\/tr>\n\n\n\n\n\n\n
                  vmtool<\/td>\nJVM\u5de5\u5177，\u5f3a\u5236GC\/\u83b7\u53d6\u5b9e\u4f8b<\/td>\nvmtool –action forceGc<\/td>\n\u5f3a\u5236Full GC<\/td>\n<\/tr>\n
                  ognl<\/td>\n\u6267\u884cOGNL\u8868\u8fbe\u5f0f<\/td>\nognl '@java.lang.System@out.println("hello")'<\/td>\n\u52a8\u6001\u8c03\u7528Java\u4ee3\u7801<\/td>\n<\/tr>\n
                  logger<\/td>\n\u67e5\u770b\/\u4fee\u6539Logger\u7ea7\u522b<\/td>\nlogger -c 1a2b3c –name ROOT –level debug<\/td>\n\u52a8\u6001\u4fee\u6539\u65e5\u5fd7\u7ea7\u522b<\/td>\n<\/tr>\n
                  profiler<\/td>\nCPU\u6027\u80fd\u5206\u6790<\/td>\nprofiler startprofiler stop –format html<\/td>\n\u751f\u6210\u706b\u7130\u56fe<\/td>\n<\/tr>\n
                  cat<\/td>\n\u6253\u5370\u6587\u4ef6\u5185\u5bb9<\/td>\ncat \/tmp\/error.log<\/td>\n\u67e5\u770b\u65e5\u5fd7<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
                  7. \u9ad8\u9891\u4f7f\u7528\u573a\u666f\u7ec4\u5408<\/h6>\n
                  🔥 \u573a\u666f1：\u63a5\u53e3\u54cd\u5e94\u6162\u6392\u67e5<\/h6>\n

                  # 1. \u770bCPU\u6700\u5fd9\u7684\u7ebf\u7a0b<\/span>
                  \nthread -n 3<\/span><\/p>\n

                  # 2. \u8ffd\u8e2a\u8017\u65f6\u65b9\u6cd5<\/span>
                  \ntrace com.web.OrderController submitOrder '#cost > 300'<\/span><\/p>\n

                  # 3. \u67e5\u770b\u5177\u4f53SQL\u6267\u884c\u65f6\u95f4（\u5982\u679c\u4f7f\u7528MyBatis）<\/span>
                  \ntrace org.apache.ibatis.executor.CachingExecutor query '#cost > 50'<\/span><\/p>\n

                  🔥 \u573a\u666f2：\u7ebf\u4e0a\u7a7a\u6307\u9488\u5f02\u5e38<\/h6>\n

                  # \u76d1\u63a7\u5f02\u5e38\u65b9\u6cd5，\u6253\u5370\u5165\u53c2<\/span>
                  \nwatch<\/span> com.web.UserController getUser '{params,throwExp}'<\/span> -e -x 2<\/span><\/p>\n

                  # \u53cd\u7f16\u8bd1\u786e\u8ba4\u4ee3\u7801\u903b\u8f91<\/span>
                  \njad –source-only com.web.UserController<\/p>\n

                  🔥 \u573a\u666f3：\u751f\u4ea7\u73af\u5883\u70ed\u4fee\u590d<\/h6>\n

                  # 1. \u53cd\u7f16\u8bd1\u7c7b<\/span>
                  \njad –source-only com.service.FaultyService ><\/span> \/tmp\/FaultyService.java<\/p>\n

                  # 2. \u7f16\u8f91\u4fee\u590d（vim \/tmp\/FaultyService.java）<\/span><\/p>\n

                  # 3. \u5185\u5b58\u7f16\u8bd1<\/span>
                  \nmc<\/span> \/tmp\/FaultyService.java -d \/tmp<\/p>\n

                  # 4. \u70ed\u66f4\u65b0<\/span>
                  \nredefine \/tmp\/com\/service\/FaultyService.class<\/p>\n

                  💡 Arthas \u4f7f\u7528\u9ec4\u91d1\u6cd5\u5219<\/h5>\n
                • \u5148dashboard\u770b\u6574\u4f53 \u2192 \u5b9a\u4f4d\u95ee\u9898\u65b9\u5411（CPU？\u5185\u5b58？\u7ebf\u7a0b？）<\/li>\n

                  \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                • thread\u6392\u67e5\u7ebf\u7a0b\u95ee\u9898 \u2192 thread -b\u6b7b\u9501\u3001thread -n\u6700\u5fd9\u7ebf\u7a0b<\/li>\n
                • trace\/watch\u6df1\u5165\u65b9\u6cd5 \u2192 \u5b9a\u4f4d\u5177\u4f53\u4ee3\u7801<\/li>\n
                • jad+mc+redefine\u70ed\u4fee\u590d \u2192 \u4e34\u65f6\u5e94\u6025<\/li>\n
                • heapdump\u4fdd\u7559\u73b0\u573a \u2192 \u4e8b\u540e\u6df1\u5ea6\u5206\u6790<\/li>\n
                  \n

                  1.2.3 JConsole \u2014\u2014 JDK \u5185\u7f6e\u53ef\u89c6\u5316\u76d1\u63a7\u5de5\u5177<\/h4>\n

                  \u542f\u52a8\u65b9\u5f0f（\u65e0\u9700\u5b89\u88c5）<\/h5>\n

                  jconsole<\/p>\n

                  \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \u70b9\u51fb\u4f60\u8981\u76d1\u63a7\u7684java\u8fdb\u7a0b，\u8fdb\u5165\u5373\u53ef\u3002 \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                  \u6838\u5fc3\u7528\u9014<\/h5>\n
                    \n
                  • \u56fe\u5f62\u5316\u5c55\u793a JVM \u5185\u5b58\u3001\u7ebf\u7a0b\u3001\u7c7b\u52a0\u8f7d\u7b49\u6307\u6807；<\/li>\n
                  • \u652f\u6301\u624b\u52a8\u89e6\u53d1 GC；<\/li>\n
                  • \u9002\u5408\u5f00\u53d1\/\u6d4b\u8bd5\u73af\u5883\u8fdb\u884c\u5b9e\u65f6\u8d8b\u52bf\u89c2\u5bdf\u4e0e\u65e9\u671f\u6cc4\u6f0f\u9884\u8b66\u3002<\/li>\n<\/ul>\n
                    \u5806\u6ea2\u51fa\u573a\u666f\u5b9e\u64cd\u6b65\u9aa4<\/h5>\n
                  • \n

                    \u8fde\u63a5\u76ee\u6807\u8fdb\u7a0b<\/p>\n

                      \n
                    • \u542f\u52a8 jconsole；<\/li>\n
                    • \u5728\u672c\u5730\u8fdb\u7a0b\u4e2d\u9009\u62e9 HeapOOM_StaticCollection \u2192 \u70b9\u51fb\u201c\u8fde\u63a5\u201d\u3002<\/li>\n<\/ul>\n<\/li>\n
                    • \n

                      \u76d1\u63a7\u5806\u5185\u5b58\u8d8b\u52bf<\/p>\n

                        \n
                      • \u5207\u6362\u5230 \u201c\u5185\u5b58\u201d \u6807\u7b7e\u9875 \u2192 \u9009\u62e9 \u201c\u5806\u5185\u5b58\u4f7f\u7528\u201d；<\/li>\n
                      • \u89c2\u5bdf\u66f2\u7ebf：\u82e5\u6301\u7eed\u4e0a\u5347\u4e14 GC \u540e\u65e0\u660e\u663e\u56de\u843d，\u5219\u9ad8\u5ea6\u7591\u4f3c\u5185\u5b58\u6cc4\u6f0f；<\/li>\n
                      • \u70b9\u51fb \u201c\u6267\u884c GC\u201d \u6309\u94ae\u9a8c\u8bc1：\u82e5\u5185\u5b58\u672a\u91ca\u653e，\u57fa\u672c\u53ef\u786e\u8ba4\u6cc4\u6f0f\u3002<\/li>\n<\/ul>\n<\/li>\n
                      • \n

                        \u5b9a\u4f4d\u95ee\u9898\u7ebf\u7a0b<\/p>\n

                          \n
                        • \u5207\u6362\u5230 \u201c\u7ebf\u7a0b\u201d \u6807\u7b7e\u9875；<\/li>\n
                        • \u67e5\u627e\u6d3b\u8dc3\u7ebf\u7a0b（\u5982 main）\u2192 \u70b9\u51fb \u201c\u5806\u6808\u8ddf\u8e2a\u201d；<\/li>\n
                        • \u53ef\u89c1\u5982 HeapOOM_StaticCollection.main() \u4e2d\u5b58\u5728\u65e0\u9650\u6dfb\u52a0\u5143\u7d20\u7684\u5faa\u73af\u3002<\/li>\n<\/ul>\n<\/li>\n
                          OOM \u9884\u8b66\u5173\u952e\u76d1\u63a7\u9879<\/h5>\n\n\u76d1\u63a7\u6307\u6807\u5f02\u5e38\u7279\u5f81\u5bf9\u5e94 OOM \u7c7b\u578b<\/tr>\n\n\n\n\n\n\n
                          \u5806\u5185\u5b58\u4f7f\u7528\u91cf<\/td>\n\u6301\u7eed\u589e\u957f，GC \u540e\u4e0d\u4e0b\u964d<\/td>\nJava heap space<\/td>\n<\/tr>\n
                          \u5143\u7a7a\u95f4（Metaspace）<\/td>\n\u7ebf\u6027\u589e\u957f，\u65e0\u5e73\u53f0\u671f<\/td>\nMetaspace<\/td>\n<\/tr>\n
                          \u7ebf\u7a0b\u6570<\/td>\n\u77ed\u65f6\u95f4\u5185\u6fc0\u589e\u81f3\u6570\u5343<\/td>\nUnable to create new native thread<\/td>\n<\/tr>\n
                          CPU \u4f7f\u7528\u7387<\/td>\n\u957f\u671f >90%，\u4e3b\u8981\u7531 GC \u7ebf\u7a0b\u5360\u7528<\/td>\nGC overhead limit exceeded<\/td>\n<\/tr>\n
                          \u76f4\u63a5\u5185\u5b58（Direct Buffer）<\/td>\n\u8fdb\u7a0b RES \u9ad8\u4f46\u5806\u5185\u5b58\u4f4e<\/td>\nDirect buffer memory<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                          \u63d0\u793a：JConsole \u867d\u529f\u80fd\u57fa\u7840，\u4f46\u80dc\u5728\u5f00\u7bb1\u5373\u7528，\u662f\u65e9\u671f\u53d1\u73b0\u95ee\u9898\u7684\u6709\u6548\u624b\u6bb5\u3002<\/p>\n

                          \u5c0f\u7ed3：\u5de5\u5177\u534f\u540c\u7b56\u7565<\/h4>\n\n\u573a\u666f\u63a8\u8350\u5de5\u5177\u7406\u7531<\/tr>\n\n\n\n\n
                          \u751f\u4ea7 OOM \u4e8b\u540e\u5206\u6790<\/td>\nMAT<\/td>\n\u6df1\u5ea6\u5206\u6790 .hprof，\u7cbe\u51c6\u5b9a\u4f4d\u6839\u56e0<\/td>\n<\/tr>\n
                          \u7ebf\u4e0a\u5b9e\u65f6\u8bca\u65ad<\/td>\nArthas<\/td>\n\u65e0\u9700\u91cd\u542f，\u52a8\u6001\u63a2\u67e5\u5bf9\u8c61\u72b6\u6001<\/td>\n<\/tr>\n
                          \u5f00\u53d1\/\u6d4b\u8bd5\u76d1\u63a7\u9884\u8b66<\/td>\nJConsole<\/td>\n\u53ef\u89c6\u5316\u8d8b\u52bf，\u5feb\u901f\u53d1\u73b0\u5f02\u5e38<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                          \u6700\u4f73\u5b9e\u8df5：<\/p>\n

                            \n
                          • \u65e5\u5e38\u5f00\u53d1\u7528 JConsole \u76d1\u63a7\u8d8b\u52bf；<\/li>\n
                          • \u7ebf\u4e0a\u7a81\u53d1 OOM \u7528 Arthas \u5feb\u901f\u91c7\u6837 + \u9a8c\u8bc1；<\/li>\n
                          • \u4e8b\u6545\u590d\u76d8\u7528 MAT \u6df1\u5ea6\u5206\u6790\u5806\u8f6c\u50a8，\u5f62\u6210\u95ed\u73af\u3002<\/li>\n<\/ul>\n
                            \n

                            \u4e8c\u3001\u5b9e\u6218\u4e00：\u5806\u5185\u5b58\u6ea2\u51fa \u2014\u2014 \u9759\u6001\u96c6\u5408\u6cc4\u6f0f（\u6700\u5e38\u89c1）<\/h3>\n

                            \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                            2.1 \u590d\u73b0\u4ee3\u7801<\/h4>\n

                            package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2<\/span>;<\/span><\/p>\n

                            import<\/span> java.<\/span>util.<\/span><\/span>ArrayList<\/span>;<\/span>
                            \nimport<\/span> java.<\/span>util.<\/span><\/span>List<\/span>;<\/span>
                            \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>TimeUnit<\/span>;<\/span><\/p>\n

                            \/**
                            \n * \u573a\u666f：\u9759\u6001\u96c6\u5408\u65e0\u9650\u5236\u5b58\u50a8，\u5bfc\u81f4GC\u65e0\u6cd5\u56de\u6536
                            \n * JVM\u53c2\u6570：-Xms256m -Xmx256m -XX:+HeapDumpOnOutOfMemoryError
                            \n * -XX:HeapDumpPath=.\/dumps\/ -XX:+PrintGCDetails
                            \n *\/<\/span>
                            \npublic<\/span> class<\/span> HeapOOM_StaticCollection<\/span> {<\/span>
                            \n \/\/ \u7f6a\u9b41\u7978\u9996：\u9759\u6001\u96c6\u5408\u751f\u547d\u5468\u671f\u4e0eJVM\u5171\u5b58\u4ea1<\/span>
                            \n private<\/span> static<\/span> final<\/span> List<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> LEAK_CACHE =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                            \n private<\/span> static<\/span> int<\/span> counter =<\/span> 0<\/span>;<\/span><\/p>\n

                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> InterruptedException<\/span> {<\/span>
                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== \u5806\u5185\u5b58\u6cc4\u6f0f\u6a21\u62df\u5f00\u59cb ==="<\/span>)<\/span>;<\/span>
                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u5806\u5185\u5b58\u4e0a\u9650: -Xmx256m"<\/span>)<\/span>;<\/span>
                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u6bcf100ms\u5206\u914d1MB，\u6dfb\u52a0\u81f3\u9759\u6001List\\\\n"<\/span>)<\/span>;<\/span><\/p>\n

                            while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                            \n \/\/ \u6bcf\u6b21\u5206\u914d1MB，\u6301\u7eed\u6dfb\u52a0<\/span>
                            \n byte<\/span>[<\/span>]<\/span> chunk =<\/span> new<\/span> byte<\/span>[<\/span>1024<\/span> *<\/span> 1024<\/span>]<\/span>;<\/span>
                            \n LEAK_CACHE.<\/span>add<\/span>(<\/span>chunk)<\/span>;<\/span>
                            \n counter++<\/span>;<\/span><\/p>\n

                            if<\/span> (<\/span>counter %<\/span> 50<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5df2\u5206\u914d: %d MB | \u96c6\u5408\u5927\u5c0f: %d | \u5269\u4f59\u5806: %d MB%n"<\/span>,<\/span>
                            \n counter,<\/span> LEAK_CACHE.<\/span>size<\/span>(<\/span>)<\/span>,<\/span>
                            \n Runtime<\/span>.<\/span>getRuntime<\/span>(<\/span>)<\/span>.<\/span>freeMemory<\/span>(<\/span>)<\/span> \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span>
                            \n TimeUnit<\/span>.<\/span>MILLISECONDS.<\/span>sleep<\/span>(<\/span>100<\/span>)<\/span>;<\/span>
                            \n }<\/span>
                            \n }<\/span>
                            \n }<\/span>
                            \n}<\/span><\/p>\n

                            2.2 JVM\u5185\u5b58\u53d8\u5316\u56fe\u89e3<\/h4>\n

                            \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                            \n\u2502 JVM \u5806\u5185\u5b58\u6f14\u53d8\u8fc7\u7a0b \u2502
                            \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                            \n\u2502 \u9636\u6bb5 \u2502 \u5185\u5b58\u533a\u57df \u2502 \u73b0\u8c61\u63cf\u8ff0 \u2502
                            \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                            \n\u2502 0-100MB \u2502 Eden\u533a \u2502 Minor GC\u9891\u7e41，\u5bf9\u8c61 \u2502
                            \n\u2502 \u2502 \u2502 \u5927\u90e8\u5206\u88ab\u56de\u6536 \u2502
                            \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                            \n\u2502 100-200MB \u2502 Survivor\u2192\u8001\u5e74\u4ee3 \u2502 \u9759\u6001\u96c6\u5408\u5f3a\u5f15\u7528， \u2502
                            \n\u2502 \u2502 \u2502 \u5bf9\u8c61\u664b\u5347\u8001\u5e74\u4ee3 \u2502
                            \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                            \n\u2502 200-240MB \u2502 \u8001\u5e74\u4ee3 \u2502 Full GC\u9891\u7387\u589e\u52a0， \u2502
                            \n\u2502 \u2502 \u2502 \u4f46\u56de\u6536\u6781\u5c11 \u2502
                            \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                            \n\u2502 >240MB \u2502 \u5168\u4f53\u5806 \u2502 GC\u56de\u6536\u7387＜2% \u2502
                            \n\u2502 \u2502 \u2502 \u629b\u51faOOM\u5f02\u5e38 \u2502
                            \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/p>\n

                            \u5185\u5b58\u53d8\u5316\u65f6\u5e8f\u8be6\u89e3：
                            \n1. \u521d\u671f（0-100MB）：Eden\u533a\u9891\u7e41Minor GC，\u90e8\u5206\u5e78\u5b58\u5bf9\u8c61\u88ab\u9759\u6001\u96c6\u5408\u5f15\u7528，\u65e0\u6cd5\u56de\u6536
                            \n2. \u4e2d\u671f（100-200MB）：\u5bf9\u8c61\u664b\u5347\u81f3\u8001\u5e74\u4ee3，\u8001\u5e74\u4ee3\u5360\u7528\u7387\u6301\u7eed\u6500\u5347
                            \n3. \u540e\u671f（200-240MB）：Full GC\u9891\u7e41\u89e6\u53d1，\u4f46\u56de\u6536\u6548\u679c\u6781\u5dee
                            \n4. \u4e34\u754c（＞240MB）：Allocation Failure，OOM\u5f02\u5e38\u629b\u51fa<\/p>\n

                            2.3 \u590d\u73b0\u4e0e\u89c2\u5bdf<\/h4>\n

                            \u6ce8\u610f：\u9700\u8981\u63d0\u524d\u521b\u5efa\u597dcom\/example\/aliyunDemo\/test\/jvm2\/dumps\u76ee\u5f55，\u5426\u5219jvm\u4e0d\u4f1a\u751f\u6210.hprof\u6587\u4ef6\u3002<\/p>\n

                            cd<\/span> F:\\\\<\/span>study\\\\<\/span>code\\\\<\/span>aliyunDemo\\\\<\/span>src\\\\<\/span>main\\\\<\/span>java<\/p>\n

                            # \u7f16\u8bd1（\u6307\u5b9aUTF-8）<\/span>
                            \njavac -encoding UTF-8 com\/example\/aliyunDemo\/test\/jvm2\/HeapOOM_LeakDemo.java<\/p>\n

                            # \u8fd0\u884c（\u8bbe\u7f6e\u5806\u5185\u5b58256M，\u5f00\u542f\u5806\u8f6c\u50a8，\u6307\u5b9adump\u6587\u4ef6\u8def\u5f84）<\/span>
                            \njava -Xms256m -Xmx256m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=<\/span>.\/com\/example\/aliyunDemo\/test\/jvm2\/dumps\/HeapOOM_LeakDemo.hprof -XX:+PrintGCDetails com.example.aliyunDemo.test.jvm2.HeapOOM_LeakDemo<\/p>\n

                            \u6267\u884c\u7ed3\u679c： \"OOM\u63a7\u5236\u53f0\u8f93\u51fa\" \"GC\u65e5\u5fd7\u8be6\u60c5\"<\/p>\n

                            \u5173\u952e\u65e5\u5fd7\u89e3\u8bfb：<\/p>\n

                            java.lang.OutOfMemoryError: Java heap space
                            \nDumping heap to .\/com\/example\/aliyunDemo\/test\/jvm2\/dumps\/java_pid1234.hprof …
                            \nHeap dump file created [256MB in 1.2 secs]<\/p>\n

                            2.4 MAT \u5185\u5b58\u5206\u6790\u5b9e\u6218<\/h4>\n

                            Step 1: \u6253\u5f00MAT\u5de5\u5177<\/h5>\n

                            \"MAT\u542f\u52a8\u754c\u9762\"<\/p>\n

                            Step 2: \u52a0\u8f7d\u5806\u8f6c\u50a8\u6587\u4ef6<\/h5>\n

                            \"\u52a0\u8f7dhprof\u6587\u4ef6\"<\/p>\n

                              \n
                            • File \u2192 Open Heap Dump<\/li>\n
                            • \u9009\u62e9\u751f\u6210\u7684 HeapOOM_LeakDemo.hprof<\/li>\n
                            • \u9009\u62e9 \u201cLeak Suspects Report\u201d \u62a5\u544a\u7c7b\u578b<\/li>\n<\/ul>\n
                              Step 3: \u5feb\u901f\u8bca\u65ad\u5165\u53e3<\/h5>\n

                              \"Overview\u6982\u89c8\"<\/p>\n

                                \n
                              • Overview：\u67e5\u770bJVM\u8fd0\u884c\u65f6\u4fe1\u606f\u3001\u73af\u5883\u53c2\u6570<\/li>\n
                              • \u70b9\u51fb Leak Suspects：\u76f4\u63a5\u5b9a\u4f4d\u7591\u4f3c\u6cc4\u6f0f\u70b9<\/li>\n<\/ul>\n
                                Step 4: \u89e3\u8bfb\u6cc4\u6f0f\u62a5\u544a<\/h5>\n

                                \"\u6cc4\u6f0f\u5acc\u7591\u62a5\u544a\"<\/p>\n

                                \u62a5\u544a\u6838\u5fc3\u4fe1\u606f：<\/p>\n

                                  \n
                                • \u2705 \u95ee\u9898\u63cf\u8ff0：Problem Suspect 1<\/li>\n
                                • 📊 \u5185\u5b58\u5360\u6bd4：\u4e00\u4e2a\u5bf9\u8c61\u5b9e\u4f8b\u5360\u7528 99%\u4ee5\u4e0a \u7684\u5806\u5185\u5b58<\/li>\n<\/ul>\n
                                  Step 5: \u5b9a\u4f4dGC Roots\u94fe\u8def<\/h5>\n

                                  \"\u67e5\u770b\u8be6\u60c5\"<\/p>\n

                                • \u70b9\u51fb\u5acc\u7591\u5bf9\u8c61\u8be6\u60c5<\/li>\n
                                • \u53f3\u952e \u2192 Path to GC Roots<\/li>\n
                                • \u9009\u62e9 exclude weak references<\/li>\n
                                  Step 6: \u6839\u56e0\u786e\u8ba4<\/h5>\n

                                  \"GC \"\u6700\u7ec8\u5b9a\u4f4d\"<\/p>\n

                                  \u5b9a\u4f4d\u94fe\u8def：<\/p>\n

                                  Thread main
                                  \n \u2514\u2500 com.example.HeapOOM_StaticCollection
                                  \n \u2514\u2500 STATIC_CACHE (\u9759\u6001\u53d8\u91cf)
                                  \n \u2514\u2500 ArrayList (\u96c6\u5408\u5b9e\u4f8b)
                                  \n \u2514\u2500 elementData (\u5b58\u50a8\u6570\u7ec4)
                                  \n \u2514\u2500 byte[] (\u6cc4\u6f0f\u5bf9\u8c61)<\/p>\n

                                  \u7ed3\u8bba：STATIC_CACHE \u9759\u6001\u96c6\u5408\u6301\u6709\u6240\u6709 byte[] \u7684\u5f3a\u5f15\u7528，GC\u65e0\u6cd5\u56de\u6536，\u5bfc\u81f4\u5185\u5b58\u6cc4\u6f0f\u3002<\/p>\n

                                  2.5 \u4e09\u5957\u89e3\u51b3\u65b9\u6848<\/h4>\n

                                  \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                  \u2705 \u65b9\u6848\u4e00：\u5bb9\u91cf\u4e0a\u9650 + FIFO\u6dd8\u6c70（\u5feb\u901f\u6574\u6539）<\/h5>\n

                                  \u9002\u7528\u4e8e：\u4e1a\u52a1\u5141\u8bb8\u4e22\u5f03\u65e7\u6570\u636e\u7684\u573a\u666f<\/p>\n

                                  package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                  import<\/span> java.<\/span>util.<\/span><\/span>ArrayList<\/span>;<\/span>
                                  \nimport<\/span> java.<\/span>util.<\/span><\/span>List<\/span>;<\/span><\/p>\n

                                  \/**
                                  \n * \u89e3\u51b3\u65b9\u68481：\u56fa\u5b9a\u5bb9\u91cf + FIFO\u6dd8\u6c70\u673a\u5236
                                  \n *\/<\/span>
                                  \npublic<\/span> class<\/span> HeapOOM_Fix1_CapacityLimit<\/span> {<\/span>
                                  \n \/\/ \u9759\u6001\u7f13\u5b58 – \u4f46\u6709\u5bb9\u91cf\u4e0a\u9650<\/span>
                                  \n private<\/span> static<\/span> final<\/span> List<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> FIXED_CACHE =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                  \n private<\/span> static<\/span> final<\/span> int<\/span> MAX_CAPACITY =<\/span> 180<\/span>;<\/span> \/\/ \u4e0a\u9650180MB（\u5c0f\u4e8e\u5806\u5185\u5b58）<\/span><\/p>\n

                                  \/**
                                  \n * \u7ebf\u7a0b\u5b89\u5168\u7684\u6dfb\u52a0\u65b9\u6cd5
                                  \n * FIFO\u7b56\u7565：\u6dd8\u6c70\u6700\u8001\u7684\u6570\u636e
                                  \n *\/<\/span>
                                  \n private<\/span> static<\/span> void<\/span> safeAdd<\/span>(<\/span>byte<\/span>[<\/span>]<\/span> data)<\/span> {<\/span>
                                  \n synchronized<\/span> (<\/span>FIXED_CACHE)<\/span> {<\/span>
                                  \n \/\/ \u8fbe\u5230\u4e0a\u9650\u65f6，\u79fb\u9664\u5934\u90e8\u5143\u7d20（\u6700\u65e9\u52a0\u5165\u7684）<\/span>
                                  \n while<\/span> (<\/span>FIXED_CACHE.<\/span>size<\/span>(<\/span>)<\/span> >=<\/span> MAX_CAPACITY)<\/span> {<\/span>
                                  \n FIXED_CACHE.<\/span>remove<\/span>(<\/span>0<\/span>)<\/span>;<\/span>
                                  \n }<\/span>
                                  \n FIXED_CACHE.<\/span>add<\/span>(<\/span>data)<\/span>;<\/span>
                                  \n }<\/span>
                                  \n }<\/span><\/p>\n

                                  public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> InterruptedException<\/span> {<\/span>
                                  \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== FIFO\u5bb9\u91cf\u4e0a\u9650\u65b9\u6848 ==="<\/span>)<\/span>;<\/span>
                                  \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u6700\u5927\u7f13\u5b58\u6761\u76ee: "<\/span> +<\/span> MAX_CAPACITY +<\/span> " MB"<\/span>)<\/span>;<\/span><\/p>\n

                                  int<\/span> count =<\/span> 0<\/span>;<\/span>
                                  \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                  \n safeAdd<\/span>(<\/span>new<\/span> byte<\/span>[<\/span>1024<\/span> *<\/span> 1024<\/span>]<\/span>)<\/span>;<\/span> \/\/ 1MB<\/span>
                                  \n count++<\/span>;<\/span><\/p>\n

                                  if<\/span> (<\/span>count %<\/span> 50<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                  \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5f53\u524d\u7f13\u5b58: %d MB, \u5df2\u6dd8\u6c70: %d MB%n"<\/span>,<\/span>
                                  \n FIXED_CACHE.<\/span>size<\/span>(<\/span>)<\/span>,<\/span> count –<\/span> FIXED_CACHE.<\/span>size<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                  \n }<\/span>
                                  \n Thread<\/span>.<\/span>sleep<\/span>(<\/span>50<\/span>)<\/span>;<\/span>
                                  \n }<\/span>
                                  \n }<\/span>
                                  \n}<\/span><\/p>\n

                                  \u65b9\u6848\u4f18\u52bf：<\/p>\n

                                    \n
                                  • \u2705 \u5b9e\u73b0\u7b80\u5355，\u6539\u52a8\u6210\u672c\u4f4e<\/li>\n
                                  • \u2705 \u5185\u5b58\u53ef\u63a7，\u6c38\u4e0dOOM<\/li>\n
                                  • \u2705 FIFO\u7b56\u7565\u7b26\u5408\u90e8\u5206\u4e1a\u52a1\u573a\u666f<\/li>\n<\/ul>\n
                                    \n
                                    \u2705 \u65b9\u6848\u4e8c：\u5f31\u5f15\u7528 + WeakHashMap（JVM\u81ea\u52a8\u56de\u6536）<\/h5>\n

                                    \u9002\u7528\u4e8e：\u5185\u5b58\u654f\u611f\u578b\u7f13\u5b58，\u5141\u8bb8GC\u65f6\u4e22\u5f03<\/p>\n

                                    package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                    import<\/span> java.<\/span>util.<\/span><\/span>Collections<\/span>;<\/span>
                                    \nimport<\/span> java.<\/span>util.<\/span><\/span>Map<\/span>;<\/span>
                                    \nimport<\/span> java.<\/span>util.<\/span><\/span>WeakHashMap<\/span>;<\/span><\/p>\n

                                    \/**
                                    \n * \u89e3\u51b3\u65b9\u68482：\u5f31\u5f15\u7528\u81ea\u52a8\u56de\u6536
                                    \n *\/<\/span>
                                    \npublic<\/span> class<\/span> HeapOOM_Fix2_WeakReference<\/span> {<\/span>
                                    \n \/\/ WeakHashMap：key\u65e0\u5f3a\u5f15\u7528\u65f6，GC\u81ea\u52a8\u6e05\u7406\u5bf9\u5e94entry<\/span>
                                    \n private<\/span> static<\/span> final<\/span> Map<\/span><<\/span>String<\/span>,<\/span> byte<\/span>[<\/span>]<\/span>><\/span> WEAK_CACHE =<\/span>
                                    \n Collections<\/span>.<\/span>synchronizedMap<\/span>(<\/span>new<\/span> WeakHashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>)<\/span>;<\/span><\/p>\n

                                    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> InterruptedException<\/span> {<\/span>
                                    \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== \u5f31\u5f15\u7528\u7f13\u5b58\u65b9\u6848 ==="<\/span>)<\/span>;<\/span><\/p>\n

                                    int<\/span> index =<\/span> 0<\/span>;<\/span>
                                    \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                    \n String<\/span> key =<\/span> "key_"<\/span> +<\/span> (<\/span>index++<\/span>)<\/span>;<\/span>
                                    \n WEAK_CACHE.<\/span>put<\/span>(<\/span>key,<\/span> new<\/span> byte<\/span>[<\/span>1024<\/span> *<\/span> 1024<\/span>]<\/span>)<\/span>;<\/span><\/p>\n

                                    \/\/ \u4e3b\u52a8\u89e6\u53d1GC（\u4ec5\u4e3a\u6f14\u793aWeakHashMap\u7279\u6027）<\/span>
                                    \n if<\/span> (<\/span>index %<\/span> 30<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                    \n System<\/span>.<\/span>gc<\/span>(<\/span>)<\/span>;<\/span>
                                    \n Thread<\/span>.<\/span>sleep<\/span>(<\/span>100<\/span>)<\/span>;<\/span>
                                    \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u7f13\u5b58\u5927\u5c0f: %d, \u5f53\u524d\u7d22\u5f15: %d%n"<\/span>,<\/span>
                                    \n WEAK_CACHE.<\/span>size<\/span>(<\/span>)<\/span>,<\/span> index)<\/span>;<\/span>
                                    \n }<\/span><\/p>\n

                                    Thread<\/span>.<\/span>sleep<\/span>(<\/span>20<\/span>)<\/span>;<\/span>
                                    \n }<\/span>
                                    \n }<\/span>
                                    \n}<\/span><\/p>\n

                                    \u6838\u5fc3\u539f\u7406：<\/p>\n

                                    1. \u5f31\u5f15\u7528\u5bf9\u8c61：\u4e0b\u6b21GC\u65f6\u5fc5\u5b9a\u56de\u6536
                                    \n2. WeakHashMap：key\u4e3a\u5f31\u5f15\u7528，value\u4e3a\u5f3a\u5f15\u7528
                                    \n3. key\u88ab\u56de\u6536\u65f6，entry\u81ea\u52a8\u4ecemap\u79fb\u9664<\/p>\n

                                    \u9002\u7528\u573a\u666f：<\/p>\n

                                      \n
                                    • \u2705 \u56fe\u7247\u7f13\u5b58\u3001\u5bf9\u8c61\u6c60<\/li>\n
                                    • \u2705 \u4e34\u65f6\u8ba1\u7b97\u7ed3\u679c\u7f13\u5b58<\/li>\n
                                    • \u2705 \u53ef\u91cd\u5efa\u7684\u6570\u636e<\/li>\n<\/ul>\n
                                      \n
                                      \u2705 \u65b9\u6848\u4e09：Guava Cache（\u751f\u4ea7\u7ea7\u63a8\u8350）<\/h5>\n

                                      \u9002\u7528\u4e8e：\u9ad8\u5e76\u53d1\u3001\u7b56\u7565\u590d\u6742\u7684\u751f\u4ea7\u73af\u5883<\/p>\n

                                      package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                      import<\/span> com.<\/span>google.<\/span>common.<\/span>cache.<\/span><\/span>*<\/span>;<\/span>
                                      \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>TimeUnit<\/span>;<\/span><\/p>\n

                                      \/**
                                      \n * \u89e3\u51b3\u65b9\u68483：Guava Cache – \u751f\u4ea7\u73af\u5883\u6807\u914d
                                      \n * \u4f9d\u8d56：com.google.guava:guava:31.1-jre
                                      \n *\/<\/span>
                                      \npublic<\/span> class<\/span> HeapOOM_Fix3_GuavaCache<\/span> {<\/span><\/p>\n

                                      private<\/span> static<\/span> final<\/span> Cache<\/span><<\/span>String<\/span>,<\/span> byte<\/span>[<\/span>]<\/span>><\/span> PRODUCTION_CACHE =<\/span>
                                      \n CacheBuilder<\/span>.<\/span>newBuilder<\/span>(<\/span>)<\/span>
                                      \n \/\/ 1\ufe0f\u20e3 \u5bb9\u91cf\u63a7\u5236<\/span>
                                      \n .<\/span>maximumSize<\/span>(<\/span>150<\/span>)<\/span> \/\/ \u6700\u5927\u6761\u76ee\u6570<\/span>
                                      \n .<\/span>maximumWeight<\/span>(<\/span>180<\/span>)<\/span> \/\/ \u6700\u5927\u6743\u91cd（MB）<\/span>
                                      \n .<\/span>weigher<\/span>(<\/span>(<\/span>Weigher<\/span><<\/span>String<\/span>,<\/span> byte<\/span>[<\/span>]<\/span>><\/span>)<\/span> (<\/span>key,<\/span> value)<\/span> -><\/span> 1<\/span>)<\/span> \/\/ \u6bcf\u9879\u6743\u91cd1<\/span><\/p>\n

                                      \/\/ 2\ufe0f\u20e3 \u8fc7\u671f\u7b56\u7565（\u4e09\u9009\u4e00\u6216\u7ec4\u5408）<\/span>
                                      \n .<\/span>expireAfterWrite<\/span>(<\/span>3<\/span>,<\/span> TimeUnit<\/span>.<\/span>MINUTES)<\/span> \/\/ \u5199\u5165\u540e3\u5206\u949f\u8fc7\u671f<\/span>
                                      \n .<\/span>expireAfterAccess<\/span>(<\/span>1<\/span>,<\/span> TimeUnit<\/span>.<\/span>MINUTES)<\/span> \/\/ 1\u5206\u949f\u672a\u8bbf\u95ee\u5219\u8fc7\u671f<\/span>
                                      \n \/\/ .refreshAfterWrite(2, TimeUnit.MINUTES) \/\/ 2\u5206\u949f\u540e\u81ea\u52a8\u5237\u65b0（\u9700\u642d\u914dLoadingCache）<\/span><\/p>\n

                                      \/\/ 3\ufe0f\u20e3 \u5185\u5b58\u4f18\u5316<\/span>
                                      \n .<\/span>softValues<\/span>(<\/span>)<\/span> \/\/ \u8f6f\u5f15\u7528（\u5185\u5b58\u4e0d\u8db3\u65f6\u56de\u6536）<\/span><\/p>\n

                                      \/\/ 4\ufe0f\u20e3 \u5e76\u53d1\u4f18\u5316<\/span>
                                      \n .<\/span>concurrencyLevel<\/span>(<\/span>16<\/span>)<\/span> \/\/ \u5e76\u53d1\u5199\u7ebf\u7a0b\u6570<\/span>
                                      \n .<\/span>initialCapacity<\/span>(<\/span>50<\/span>)<\/span> \/\/ \u521d\u59cb\u5bb9\u91cf<\/span><\/p>\n

                                      \/\/ 5\ufe0f\u20e3 \u7edf\u8ba1\u76d1\u63a7<\/span>
                                      \n .<\/span>recordStats<\/span>(<\/span>)<\/span> \/\/ \u5f00\u542f\u547d\u4e2d\u7387\u7edf\u8ba1<\/span><\/p>\n

                                      \/\/ 6\ufe0f\u20e3 \u79fb\u9664\u76d1\u542c<\/span>
                                      \n .<\/span>removalListener<\/span>(<\/span>(<\/span>RemovalListener<\/span><<\/span>String<\/span>,<\/span> byte<\/span>[<\/span>]<\/span>><\/span>)<\/span> notification -><\/span>
                                      \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[\u7f13\u5b58\u6dd8\u6c70] key: %s, \u539f\u56e0: %s%n"<\/span>,<\/span>
                                      \n notification.<\/span>getKey<\/span>(<\/span>)<\/span>,<\/span> notification.<\/span>getCause<\/span>(<\/span>)<\/span>)<\/span>)<\/span>
                                      \n .<\/span>build<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                      public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> InterruptedException<\/span> {<\/span>
                                      \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== Guava Cache \u751f\u4ea7\u7ea7\u65b9\u6848 ==="<\/span>)<\/span>;<\/span><\/p>\n

                                      int<\/span> index =<\/span> 0<\/span>;<\/span>
                                      \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                      \n \/\/ \u5199\u5165\u7f13\u5b58<\/span>
                                      \n PRODUCTION_CACHE.<\/span>put<\/span>(<\/span>"data_"<\/span> +<\/span> (<\/span>index++<\/span>)<\/span>,<\/span> new<\/span> byte<\/span>[<\/span>1024<\/span> *<\/span> 1024<\/span>]<\/span>)<\/span>;<\/span><\/p>\n

                                      \/\/ \u6bcf100\u6b21\u6253\u5370\u7edf\u8ba1\u4fe1\u606f<\/span>
                                      \n if<\/span> (<\/span>index %<\/span> 100<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                      \n CacheStats<\/span> stats =<\/span> PRODUCTION_CACHE.<\/span>stats<\/span>(<\/span>)<\/span>;<\/span>
                                      \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u8bf7\u6c42\u6b21\u6570: %d | \u547d\u4e2d\u7387: %.2f%% | \u6dd8\u6c70\u6570: %d%n"<\/span>,<\/span>
                                      \n index,<\/span> stats.<\/span>hitRate<\/span>(<\/span>)<\/span> *<\/span> 100<\/span>,<\/span> stats.<\/span>evictionCount<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                      \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5f53\u524d\u7f13\u5b58\u5927\u5c0f: %d | \u603b\u52a0\u8f7d\u65f6\u95f4: %d ns%n%n"<\/span>,<\/span>
                                      \n PRODUCTION_CACHE.<\/span>size<\/span>(<\/span>)<\/span>,<\/span> stats.<\/span>totalLoadTime<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                      \n }<\/span><\/p>\n

                                      Thread<\/span>.<\/span>sleep<\/span>(<\/span>50<\/span>)<\/span>;<\/span>
                                      \n }<\/span>
                                      \n }<\/span>
                                      \n}<\/span><\/p>\n

                                      Maven\u4f9d\u8d56：<\/p>\n

                                      <<\/span>dependency<\/span>><\/span><\/span>
                                      \n <<\/span>groupId<\/span>><\/span><\/span>com.google.guava<\/<\/span>groupId<\/span>><\/span><\/span>
                                      \n <<\/span>artifactId<\/span>><\/span><\/span>guava<\/<\/span>artifactId<\/span>><\/span><\/span>
                                      \n <<\/span>version<\/span>><\/span><\/span>31.1-jre<\/<\/span>version<\/span>><\/span><\/span>
                                      \n<\/<\/span>dependency<\/span>><\/span><\/span><\/p>\n

                                      \n

                                      2.6 \u65b9\u6848\u5bf9\u6bd4\u4e0e\u9009\u578b\u5efa\u8bae<\/h4>\n\n\u5bf9\u6bd4\u7ef4\u5ea6\u65b9\u68481 FIFO\u961f\u5217\u65b9\u68482 \u5f31\u5f15\u7528\u65b9\u68483 Guava Cache<\/tr>\n\n\n\n\n\n\n\n
                                      \u5b9e\u73b0\u590d\u6742\u5ea6<\/td>\n\u2b50 \u7b80\u5355<\/td>\n\u2b50\u2b50 \u4e2d\u7b49<\/td>\n\u2b50\u2b50\u2b50 \u8f83\u590d\u6742<\/td>\n<\/tr>\n
                                      \u5185\u5b58\u53ef\u63a7\u6027<\/td>\n\u2705 \u5b8c\u5168\u53ef\u63a7<\/td>\n\u274c \u4e0d\u53ef\u63a7<\/td>\n\u2705 \u7cbe\u786e\u63a7\u5236<\/td>\n<\/tr>\n
                                      \u56de\u6536\u65f6\u6548<\/td>\n\u7acb\u5373（\u6ee1\u5219\u5220）<\/td>\n\u5ef6\u8fdf（GC\u89e6\u53d1）<\/td>\n\u5373\u65f6（\u7b56\u7565\u89e6\u53d1）<\/td>\n<\/tr>\n
                                      \u5e76\u53d1\u6027\u80fd<\/td>\n\u4e00\u822c（synchronized）<\/td>\n\u8f83\u597d<\/td>\n\u6781\u597d（\u5206\u6bb5\u9501）<\/td>\n<\/tr>\n
                                      \u76d1\u63a7\u80fd\u529b<\/td>\n\u65e0<\/td>\n\u65e0<\/td>\n\u2705 \u5b8c\u6574\u7edf\u8ba1<\/td>\n<\/tr>\n
                                      \u63a8\u8350\u6307\u6570<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                                      \u9009\u578b\u5efa\u8bae：<\/p>\n

                                        \n
                                      • \u7d27\u6025\u4fee\u590d \u2192 \u65b9\u68481（5\u5206\u949f\u641e\u5b9a）<\/li>\n
                                      • \u5355\u4f53\u5e94\u7528 \u2192 \u65b9\u68481\u6216\u65b9\u68482<\/li>\n
                                      • \u5fae\u670d\u52a1\/\u9ad8\u5e76\u53d1 \u2192 \u65b9\u68483（\u9996\u9009）<\/li>\n
                                      • \u5df2\u6709\u7f13\u5b58\u4e2d\u95f4\u4ef6 \u2192 \u76f4\u63a5\u66ff\u6362\u4e3aRedis<\/li>\n<\/ul>\n

                                        \u6838\u5fc3\u539f\u5219：<\/p>\n

                                      • \u9759\u6001\u96c6\u5408 \u2248 JVM\u5e38\u9a7b\u5185\u5b58，\u5fc5\u987b\u8bbe\u4e0a\u9650<\/li>\n
                                      • \u7f13\u5b58\u5fc5\u987b\u6709\u6dd8\u6c70\u7b56\u7565（FIFO\/LRU\/\u8fc7\u671f\u65f6\u95f4）<\/li>\n
                                      • \u5927\u5bf9\u8c61\u4e0d\u8981\u957f\u671f\u9a7b\u7559\u9759\u6001\u533a<\/li>\n
                                        \n

                                        \u4e09\u3001\u5b9e\u6218\u4e8c：\u6808\u5185\u5b58\u6ea2\u51fa \u2014\u2014 \u65e0\u9650\u9012\u5f52<\/h3>\n

                                        \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                        3.1 \u590d\u73b0\u4ee3\u7801<\/h4>\n

                                        package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2<\/span>;<\/span><\/p>\n

                                        import<\/span> java.<\/span>lang.<\/span>management.<\/span><\/span>ManagementFactory<\/span>;<\/span><\/p>\n

                                        \/**
                                        \n * \u573a\u666f：\u65e0\u7ec8\u6b62\u6761\u4ef6\u7684\u9012\u5f52\u8c03\u7528，\u8017\u5c3d\u7ebf\u7a0b\u6808\u7a7a\u95f4
                                        \n * JVM\u53c2\u6570：-Xss256k (\u51cf\u5c0f\u6808\u5927\u5c0f，\u52a0\u901f\u590d\u73b0)
                                        \n *
                                        \n * \u77e5\u8bc6\u70b9：
                                        \n * – \u6bcf\u4e2a\u65b9\u6cd5\u8c03\u7528\u90fd\u4f1a\u521b\u5efa\u6808\u5e27（\u5c40\u90e8\u53d8\u91cf\u8868\u3001\u64cd\u4f5c\u6570\u6808\u3001\u52a8\u6001\u94fe\u63a5\u3001\u65b9\u6cd5\u51fa\u53e3）
                                        \n * – \u6808\u5e27\u5927\u5c0f \u2248 16-32 bytes（\u7a7a\u65b9\u6cd5）
                                        \n * – 256KB \u6808\u7a7a\u95f4\u7ea6\u53ef\u5bb9\u7eb3 8000-16000 \u5c42\u9012\u5f52
                                        \n *\/<\/span>
                                        \npublic<\/span> class<\/span> StackOOM_Recursion<\/span> {<\/span>
                                        \n private<\/span> static<\/span> int<\/span> depth =<\/span> 0<\/span>;<\/span><\/p>\n

                                        public<\/span> static<\/span> void<\/span> recursiveCall<\/span>(<\/span>)<\/span> {<\/span>
                                        \n depth++<\/span>;<\/span>
                                        \n \/\/ \u6bcf1000\u5c42\u6253\u5370\u4e00\u6b21（\u907f\u514d\u63a7\u5236\u53f0\u8f93\u51fa\u5f71\u54cd\u6027\u80fd）<\/span>
                                        \n if<\/span> (<\/span>depth %<\/span> 1000<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5f53\u524d\u9012\u5f52\u6df1\u5ea6: %d%n"<\/span>,<\/span> depth)<\/span>;<\/span>
                                        \n }<\/span>
                                        \n recursiveCall<\/span>(<\/span>)<\/span>;<\/span> \/\/ \u65e0\u9650\u9012\u5f52 \u2192 \u6808\u6ea2\u51fa<\/span>
                                        \n }<\/span><\/p>\n

                                        public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"========== \u6808\u6ea2\u51fa\u6a21\u62df\u5f00\u59cb =========="<\/span>)<\/span>;<\/span>
                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"JVM\u6808\u53c2\u6570: %s%n"<\/span>,<\/span>
                                        \n ManagementFactory<\/span>.<\/span>getRuntimeMXBean<\/span>(<\/span>)<\/span>
                                        \n .<\/span>getInputArguments<\/span>(<\/span>)<\/span>
                                        \n .<\/span>stream<\/span>(<\/span>)<\/span>
                                        \n .<\/span>filter<\/span>(<\/span>arg -><\/span> arg.<\/span>contains<\/span>(<\/span>"-Xss"<\/span>)<\/span>)<\/span>
                                        \n .<\/span>findFirst<\/span>(<\/span>)<\/span>
                                        \n .<\/span>orElse<\/span>(<\/span>"\u9ed8\u8ba4(1MB)"<\/span>)<\/span>)<\/span>;<\/span>
                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"———————————–"<\/span>)<\/span>;<\/span><\/p>\n

                                        try<\/span> {<\/span>
                                        \n recursiveCall<\/span>(<\/span>)<\/span>;<\/span>
                                        \n }<\/span> catch<\/span> (<\/span>StackOverflowError<\/span> e)<\/span> {<\/span>
                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\\\\n========== \u6808\u6ea2\u51fa\u6355\u83b7 =========="<\/span>)<\/span>;<\/span>
                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u6700\u5927\u9012\u5f52\u6df1\u5ea6: %d%n"<\/span>,<\/span> depth)<\/span>;<\/span>
                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u5f02\u5e38\u7c7b\u578b: "<\/span> +<\/span> e.<\/span>getClass<\/span>(<\/span>)<\/span>.<\/span>getSimpleName<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u89e3\u51b3\u65b9\u6848: \u9012\u5f52\u6539\u8fed\u4ee3 \/ \u589e\u52a0\u7ec8\u6b62\u6761\u4ef6"<\/span>)<\/span>;<\/span>
                                        \n }<\/span>
                                        \n }<\/span>
                                        \n}<\/span><\/p>\n

                                        3.2 JVM\u6808\u5185\u5b58\u6f14\u53d8\u56fe\u89e3<\/h4>\n

                                        \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                        \n\u2502 \u7ebf\u7a0b\u6808\u5185\u5b58\u5206\u914d\u8fc7\u7a0b \u2502
                                        \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                        \n\u2502 \u9636\u6bb5 \u2502 \u6808\u5e27\u53d8\u5316 \u2502 \u5269\u4f59\u6808\u5bb9\u91cf \u2502
                                        \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                        \n\u2502 \u6df1\u5ea6 0 \u2502 [main] \u2502 1024KB \u2502
                                        \n\u2502 \u6df1\u5ea6 1000 \u2502 [main\u2192rec…\u2192rec] \u2502 240KB (\u219316KB) \u2502
                                        \n\u2502 \u6df1\u5ea6 5000 \u2502 [main+5000\u6808\u5e27] \u2502 160KB (\u219396KB) \u2502
                                        \n\u2502 \u6df1\u5ea6 10000 \u2502 [main+10000\u6808\u5e27] \u2502 80KB (\u2193176KB) \u2502
                                        \n\u2502 \u6df1\u5ea6 15000 \u2502 [main+15000\u6808\u5e27] \u2502 0KB \u2502
                                        \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                        \n\u2502 \u6ea2\u51fa\u65f6\u523b \u2502 \u6808\u5e27\u65e0\u6cd5\u5206\u914d \u2192 StackOverflowError \u2502
                                        \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/p>\n

                                        \u6808\u5e27\u5185\u90e8\u7ed3\u6784（\u5355\u6b21\u8c03\u7528）：
                                        \n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                        \n\u2502 \u5c40\u90e8\u53d8\u91cf\u8868 (0-4\u5b57\u8282) \u2502
                                        \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                        \n\u2502 \u64cd\u4f5c\u6570\u6808 (0-4\u5b57\u8282) \u2502
                                        \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                        \n\u2502 \u52a8\u6001\u8fde\u63a5 (4-8\u5b57\u8282) \u2502
                                        \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                        \n\u2502 \u65b9\u6cd5\u51fa\u53e3 (4-8\u5b57\u8282) \u2502
                                        \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                        \n\u2248 16-32 \u5b57\u8282\/\u6808\u5e27 \u00d7 15000 \u2248 240-480KB<\/p>\n

                                        \u6808\u6ea2\u51fa\u4e09\u8981\u7d20：<\/p>\n

                                      • \u274c \u65e0\u7ec8\u6b62\u6761\u4ef6 – \u9012\u5f52\u6c38\u4e0d\u505c\u6b47<\/li>\n
                                      • \u274c \u65e0\u6df1\u5ea6\u9650\u5236 – \u65e0\u9650\u538b\u6808<\/li>\n
                                      • \u274c \u6808\u5bb9\u91cf\u56fa\u5b9a – -Xss\u53c2\u6570\u4e0d\u53ef\u52a8\u6001\u6269\u5bb9<\/li>\n
                                        \n

                                        3.3 \u8fd0\u884c\u7ed3\u679c<\/h4>\n

                                        \"\u6808\u6ea2\u51fa\u63a7\u5236\u53f0\u8f93\u51fa\"<\/p>\n

                                        \u5173\u952e\u7ed3\u8bba：<\/p>\n

                                          \n
                                        • \u2705 256KB\u6808\u7a7a\u95f4 \u2248 14782\u5c42\u9012\u5f52\u8c03\u7528<\/li>\n
                                        • \u2705 \u6bcf\u5c42\u6808\u5e27 \u2248 17.3\u5b57\u8282（\u7b26\u5408\u7406\u8bba\u503c）<\/li>\n
                                        • \u2705 \u6808\u6ea2\u51fa\u65f6\u4e0d\u4f1a\u89e6\u53d1GC（\u6808\u5185\u5b58\u975e\u5806\u7ba1\u7406）<\/li>\n<\/ul>\n
                                          \n

                                          3.4 \u89e3\u51b3\u65b9\u6848<\/h4>\n

                                          \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                          \u2705 \u65b9\u6848\u4e00：\u9012\u5f52\u6539\u8fed\u4ee3（100%\u5b89\u5168，\u9996\u9009）<\/h5>\n

                                          \u9002\u7528\u4e8e：\u6240\u6709\u9012\u5f52\u573a\u666f，\u5c24\u5176\u662f\u6df1\u5ea6\u4e0d\u53ef\u63a7\u7684\u60c5\u51b5<\/p>\n

                                          package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                          \/**
                                          \n * \u89e3\u51b3\u65b9\u68481：\u9012\u5f52 \u2192 \u8fed\u4ee3\u8f6c\u6362
                                          \n * \u539f\u7406：\u7528\u5faa\u73af\u66ff\u4ee3\u65b9\u6cd5\u8c03\u7528，\u5f7b\u5e95\u6d88\u9664\u6808\u5e27\u5806\u79ef
                                          \n *\/<\/span>
                                          \npublic<\/span> class<\/span> StackOOM_Fix1_Iteration<\/span> {<\/span><\/p>\n

                                          \/**
                                          \n * \u573a\u666f1：\u6590\u6ce2\u90a3\u5951\u6570\u5217
                                          \n *\/<\/span>
                                          \n public<\/span> static<\/span> long<\/span> fibonacci<\/span>(<\/span>int<\/span> n)<\/span> {<\/span>
                                          \n if<\/span> (<\/span>n <=<\/span> 1<\/span>)<\/span> return<\/span> n;<\/span><\/p>\n

                                          long<\/span> prev =<\/span> 0<\/span>,<\/span> curr =<\/span> 1<\/span>;<\/span>
                                          \n for<\/span> (<\/span>int<\/span> i =<\/span> 2<\/span>;<\/span> i <=<\/span> n;<\/span> i++<\/span>)<\/span> {<\/span>
                                          \n long<\/span> next =<\/span> prev +<\/span> curr;<\/span>
                                          \n prev =<\/span> curr;<\/span>
                                          \n curr =<\/span> next;<\/span>
                                          \n }<\/span>
                                          \n return<\/span> curr;<\/span>
                                          \n }<\/span><\/p>\n

                                          \/**
                                          \n * \u573a\u666f2：\u6587\u4ef6\u76ee\u5f55\u904d\u5386
                                          \n *\/<\/span>
                                          \n public<\/span> static<\/span> void<\/span> traverseDirectory<\/span>(<\/span>String<\/span> path)<\/span> {<\/span>
                                          \n java.<\/span>util.<\/span><\/span>Stack<\/span><<\/span>java.<\/span>io.<\/span><\/span>File<\/span>><\/span><\/span> stack =<\/span> new<\/span> java.<\/span>util.<\/span><\/span>Stack<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                          \n stack.<\/span>push<\/span>(<\/span>new<\/span> java.<\/span>io.<\/span><\/span>File<\/span>(<\/span>path)<\/span>)<\/span>;<\/span><\/p>\n

                                          while<\/span> (<\/span>!<\/span>stack.<\/span>isEmpty<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                          \n java.<\/span>io.<\/span><\/span>File<\/span> current =<\/span> stack.<\/span>pop<\/span>(<\/span>)<\/span>;<\/span>
                                          \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>current.<\/span>getAbsolutePath<\/span>(<\/span>)<\/span>)<\/span>;<\/span><\/p>\n

                                          java.<\/span>io.<\/span><\/span>File<\/span>[<\/span>]<\/span> children =<\/span> current.<\/span>listFiles<\/span>(<\/span>)<\/span>;<\/span>
                                          \n if<\/span> (<\/span>children !=<\/span> null<\/span>)<\/span> {<\/span>
                                          \n for<\/span> (<\/span>java.<\/span>io.<\/span><\/span>File<\/span> child :<\/span> children)<\/span> {<\/span>
                                          \n if<\/span> (<\/span>child.<\/span>isDirectory<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                          \n stack.<\/span>push<\/span>(<\/span>child)<\/span>;<\/span> \/\/ \u6a21\u62df\u9012\u5f52\u538b\u6808<\/span>
                                          \n }<\/span>
                                          \n }<\/span>
                                          \n }<\/span>
                                          \n }<\/span>
                                          \n }<\/span><\/p>\n

                                          public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                          \n \/\/ \u6d4b\u8bd5\u65e0\u9650\u5faa\u73af（\u6c38\u4e0d\u6ea2\u51fa）<\/span>
                                          \n long<\/span> start =<\/span> System<\/span>.<\/span>currentTimeMillis<\/span>(<\/span>)<\/span>;<\/span>
                                          \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 100_000_000<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>
                                          \n if<\/span> (<\/span>i %<\/span> 10_000_000<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                          \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u8fed\u4ee3\u6df1\u5ea6: %d, \u8017\u65f6: %dms%n"<\/span>,<\/span>
                                          \n i,<\/span> System<\/span>.<\/span>currentTimeMillis<\/span>(<\/span>)<\/span> –<\/span> start)<\/span>;<\/span>
                                          \n }<\/span>
                                          \n }<\/span><\/p>\n

                                          \/\/ \u6590\u6ce2\u90a3\u5951\u793a\u4f8b<\/span>
                                          \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"fib(10000) = "<\/span> +<\/span> fibonacci<\/span>(<\/span>10000<\/span>)<\/span>)<\/span>;<\/span> \/\/ \u5806\u6808\u5b89\u5168<\/span>
                                          \n }<\/span>
                                          \n}<\/span><\/p>\n

                                          \u8f6c\u6362\u5bf9\u7167\u8868：<\/p>\n\n\u9012\u5f52\u6a21\u5f0f\u8fed\u4ee3\u5b9e\u73b0\u4f18\u52bf<\/tr>\n\n\n\n\n
                                          \u5c3e\u9012\u5f52<\/td>\nfor\/while\u5faa\u73af<\/td>\n\u6027\u80fd\u6700\u597d，\u65e0\u6808\u5f00\u9500<\/td>\n<\/tr>\n
                                          \u6811\u5f62\u9012\u5f52<\/td>\nStack\u6a21\u62df<\/td>\n\u624b\u52a8\u63a7\u5236\u6df1\u5ea6<\/td>\n<\/tr>\n
                                          \u5206\u6cbb\u9012\u5f52<\/td>\n\u961f\u5217+\u5faa\u73af<\/td>\n\u53ef\u5e76\u884c\u5904\u7406<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
                                          \n
                                          \u2705 \u65b9\u6848\u4e8c：\u5c3e\u9012\u5f52\u4f18\u5316（\u501f\u52a9Lambda）<\/h5>\n

                                          \u8bf4\u660e：<\/p>\n

                                            \n
                                          • Java \u865a\u62df\u673a\u4e0d\u652f\u6301\u5c3e\u9012\u5f52\u4f18\u5316（Tail Call Optimization），\u5373\u4f7f\u5199\u6210\u5c3e\u9012\u5f52\u5f62\u5f0f，\u4ecd\u4f1a\u521b\u5efa\u65b0\u6808\u5e27\u3002<\/li>\n
                                          • \u56e0\u6b64，\u6240\u8c13\u201c\u5c3e\u9012\u5f52\u4f18\u5316\u201d\u5728 Java \u4e2d\u9700\u501f\u52a9 Stream\u3001\u5faa\u73af\u6216\u7b2c\u4e09\u65b9\u5e93（\u5982 Vavr） \u6a21\u62df\u3002<\/li>\n<\/ul>\n

                                            package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                            import<\/span> java.<\/span>util.<\/span>function.<\/span><\/span>Supplier<\/span>;<\/span>
                                            \nimport<\/span> java.<\/span>util.<\/span>stream.<\/span><\/span>Stream<\/span>;<\/span><\/p>\n

                                            \/**
                                            \n * \u89e3\u51b3\u65b9\u68482：\u6a21\u62df\u5c3e\u9012\u5f52\u4f18\u5316
                                            \n * \u539f\u7406：\u5c06\u9012\u5f52\u8c03\u7528\u8f6c\u5316\u4e3aSupplier\u5ef6\u8fdf\u6267\u884c
                                            \n *\/<\/span>
                                            \npublic<\/span> class<\/span> StackOOM_Fix2_TailCallOptimization<\/span> {<\/span><\/p>\n

                                            \/**
                                            \n * \u5c3e\u9012\u5f52\u63a5\u53e3
                                            \n *\/<\/span>
                                            \n @FunctionalInterface<\/span>
                                            \n interface<\/span> TailRecursion<\/span><<\/span>T<\/span>><\/span><\/span> {<\/span>
                                            \n TailRecursion<\/span><<\/span>T<\/span>><\/span><\/span> apply<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                            default<\/span> boolean<\/span> isFinished<\/span>(<\/span>)<\/span> {<\/span>
                                            \n return<\/span> false<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            default<\/span> T<\/span> getResult<\/span>(<\/span>)<\/span> {<\/span>
                                            \n throw<\/span> new<\/span> UnsupportedOperationException<\/span>(<\/span>"\u65e0\u7ed3\u679c"<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/**
                                            \n * \u9012\u5f52\u6267\u884c\u5668 – \u771f\u6b63\u7684\u4f18\u5316\u5728\u8fd9\u91cc
                                            \n *\/<\/span>
                                            \n static<\/span> <<\/span>T<\/span>><\/span><\/span> T<\/span> execute<\/span>(<\/span>TailRecursion<\/span><<\/span>T<\/span>><\/span><\/span> recursion)<\/span> {<\/span>
                                            \n while<\/span> (<\/span>!<\/span>recursion.<\/span>isFinished<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                            \n recursion =<\/span> recursion.<\/span>apply<\/span>(<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n return<\/span> recursion.<\/span>getResult<\/span>(<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n }<\/span><\/p>\n

                                            \/**
                                            \n * \u5c3e\u9012\u5f52\u9636\u4e58
                                            \n *\/<\/span>
                                            \n public<\/span> static<\/span> long<\/span> factorialTail<\/span>(<\/span>int<\/span> n,<\/span> long<\/span> acc)<\/span> {<\/span>
                                            \n class<\/span> FactorialRecursion<\/span> implements<\/span> TailRecursion<\/span><<\/span>Long<\/span>><\/span><\/span> {<\/span>
                                            \n private<\/span> final<\/span> int<\/span> currentN;<\/span>
                                            \n private<\/span> final<\/span> long<\/span> currentAcc;<\/span><\/p>\n

                                            FactorialRecursion<\/span>(<\/span>int<\/span> n,<\/span> long<\/span> acc)<\/span> {<\/span>
                                            \n this<\/span>.<\/span>currentN =<\/span> n;<\/span>
                                            \n this<\/span>.<\/span>currentAcc =<\/span> acc;<\/span>
                                            \n }<\/span><\/p>\n

                                            @Override<\/span>
                                            \n public<\/span> TailRecursion<\/span><<\/span>Long<\/span>><\/span><\/span> apply<\/span>(<\/span>)<\/span> {<\/span>
                                            \n if<\/span> (<\/span>currentN <=<\/span> 1<\/span>)<\/span> {<\/span>
                                            \n return<\/span> new<\/span> TailResult<\/span><<\/span>><\/span><\/span>(<\/span>currentAcc)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n return<\/span> new<\/span> FactorialRecursion<\/span>(<\/span>currentN –<\/span> 1<\/span>,<\/span> currentAcc *<\/span> currentN)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            @Override<\/span>
                                            \n public<\/span> boolean<\/span> isFinished<\/span>(<\/span>)<\/span> {<\/span>
                                            \n return<\/span> false<\/span>;<\/span>
                                            \n }<\/span>
                                            \n }<\/span><\/p>\n

                                            class<\/span> TailResult<\/span><<\/span>T<\/span>><\/span><\/span> implements<\/span> TailRecursion<\/span><<\/span>T<\/span>><\/span><\/span> {<\/span>
                                            \n private<\/span> final<\/span> T<\/span> result;<\/span><\/p>\n

                                            TailResult<\/span>(<\/span>T<\/span> result)<\/span> {<\/span>
                                            \n this<\/span>.<\/span>result =<\/span> result;<\/span>
                                            \n }<\/span><\/p>\n

                                            @Override<\/span>
                                            \n public<\/span> TailRecursion<\/span><<\/span>T<\/span>><\/span><\/span> apply<\/span>(<\/span>)<\/span> {<\/span>
                                            \n throw<\/span> new<\/span> UnsupportedOperationException<\/span>(<\/span>"\u5df2\u7ec8\u6b62"<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            @Override<\/span>
                                            \n public<\/span> boolean<\/span> isFinished<\/span>(<\/span>)<\/span> {<\/span>
                                            \n return<\/span> true<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            @Override<\/span>
                                            \n public<\/span> T<\/span> getResult<\/span>(<\/span>)<\/span> {<\/span>
                                            \n return<\/span> result;<\/span>
                                            \n }<\/span>
                                            \n }<\/span><\/p>\n

                                            return<\/span> TailRecursion<\/span>.<\/span>execute<\/span>(<\/span>new<\/span> FactorialRecursion<\/span>(<\/span>n,<\/span> acc)<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/**
                                            \n * Stream\u6a21\u62df\u5c3e\u9012\u5f52（\u7b80\u6d01\u7248）
                                            \n *\/<\/span>
                                            \n public<\/span> static<\/span> void<\/span> streamTailCall<\/span>(<\/span>int<\/span> max)<\/span> {<\/span>
                                            \n Stream<\/span>.<\/span>iterate<\/span>(<\/span>0<\/span>,<\/span> i -><\/span> i +<\/span> 1<\/span>)<\/span>
                                            \n .<\/span>limit<\/span>(<\/span>max)<\/span>
                                            \n .<\/span>parallel<\/span>(<\/span>)<\/span> \/\/ \u81ea\u52a8\u5e76\u884c<\/span>
                                            \n .<\/span>forEach<\/span>(<\/span>i -><\/span> {<\/span>
                                            \n if<\/span> (<\/span>i %<\/span> 1_000_000<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5c3e\u9012\u5f52\u6df1\u5ea6: %d (\u6808\u5b89\u5168)%n"<\/span>,<\/span> i)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n }<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                            \n \/\/ \u6d4b\u8bd5\u5c3e\u9012\u5f52\u9636\u4e58<\/span>
                                            \n long<\/span> result =<\/span> factorialTail<\/span>(<\/span>100_000<\/span>,<\/span> 1<\/span>)<\/span>;<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u5c3e\u9012\u5f52\u9636\u4e58\u7ed3\u679c(\u622a\u65ad): "<\/span> +<\/span> result)<\/span>;<\/span><\/p>\n

                                            \/\/ \u6d4b\u8bd5Stream\u7248\u672c<\/span>
                                            \n streamTailCall<\/span>(<\/span>10_000_000<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n}<\/span><\/p>\n

                                            \n
                                            \u2705 \u65b9\u6848\u4e09：\u6df1\u5ea6\u9650\u5236 + \u5206\u6cbb\u7b56\u7565（\u5b89\u5168\u9012\u5f52）<\/h5>\n

                                            \u9002\u7528\u4e8e：\u5fc5\u987b\u4f7f\u7528\u9012\u5f52\u8bed\u4e49\u7684\u573a\u666f（\u5982\u6811\u64cd\u4f5c\u3001\u7f16\u8bd1\u5668）<\/p>\n

                                            package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                            \/**
                                            \n * \u89e3\u51b3\u65b9\u68483：\u53d7\u63a7\u9012\u5f52 – \u6df1\u5ea6\u9650\u5236 + \u5206\u6cbb + \u91cd\u8bd5
                                            \n *\/<\/span>
                                            \npublic<\/span> class<\/span> StackOOM_Fix3_SafeRecursion<\/span> {<\/span><\/p>\n

                                            \/\/ \u9ed8\u8ba4\u6700\u5927\u9012\u5f52\u6df1\u5ea6（\u755920%\u7f13\u51b2）<\/span>
                                            \n private<\/span> static<\/span> final<\/span> int<\/span> MAX_DEPTH =<\/span> 8000<\/span>;<\/span><\/p>\n

                                            \/**
                                            \n * \u5b89\u5168\u9012\u5f52\u6267\u884c\u5668
                                            \n * @param task \u9012\u5f52\u4efb\u52a1
                                            \n * @param maxDepth \u6700\u5927\u5141\u8bb8\u6df1\u5ea6
                                            \n *\/<\/span>
                                            \n public<\/span> static<\/span> <<\/span>T<\/span>><\/span><\/span> T<\/span> executeRecursive<\/span>(<\/span>RecursiveTask<\/span><<\/span>T<\/span>><\/span><\/span> task,<\/span> int<\/span> maxDepth)<\/span> {<\/span>
                                            \n return<\/span> task.<\/span>compute<\/span>(<\/span>0<\/span>,<\/span> maxDepth)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/**
                                            \n * \u9012\u5f52\u4efb\u52a1\u63a5\u53e3
                                            \n *\/<\/span>
                                            \n @FunctionalInterface<\/span>
                                            \n interface<\/span> RecursiveTask<\/span><<\/span>T<\/span>><\/span><\/span> {<\/span>
                                            \n T<\/span> compute<\/span>(<\/span>int<\/span> depth,<\/span> int<\/span> maxDepth)<\/span>;<\/span><\/p>\n

                                            default<\/span> void<\/span> checkDepth<\/span>(<\/span>int<\/span> depth,<\/span> int<\/span> maxDepth)<\/span> {<\/span>
                                            \n if<\/span> (<\/span>depth ><\/span> maxDepth)<\/span> {<\/span>
                                            \n throw<\/span> new<\/span> StackOverflowError<\/span>(<\/span>
                                            \n String<\/span>.<\/span>format<\/span>(<\/span>"\u9012\u5f52\u6df1\u5ea6\u8d85\u9650: %d > %d"<\/span>,<\/span> depth,<\/span> maxDepth)<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n }<\/span>
                                            \n }<\/span><\/p>\n

                                            \/**
                                            \n * \u793a\u4f8b1：\u5e26\u6df1\u5ea6\u9650\u5236\u7684\u9636\u4e58
                                            \n *\/<\/span>
                                            \n public<\/span> static<\/span> long<\/span> safeFactorial<\/span>(<\/span>int<\/span> n)<\/span> {<\/span>
                                            \n if<\/span> (<\/span>n ><\/span> MAX_DEPTH)<\/span> {<\/span>
                                            \n \/\/ \u5206\u6cbb\u5904\u7406：n! = (n\/2)! \u00d7 \u5269\u4f59\u90e8\u5206<\/span>
                                            \n int<\/span> mid =<\/span> n \/<\/span> 2<\/span>;<\/span>
                                            \n return<\/span> safeFactorial<\/span>(<\/span>mid)<\/span> *<\/span> product<\/span>(<\/span>mid +<\/span> 1<\/span>,<\/span> n)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n return<\/span> factorialInternal<\/span>(<\/span>n,<\/span> 0<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            private<\/span> static<\/span> long<\/span> factorialInternal<\/span>(<\/span>int<\/span> n,<\/span> int<\/span> depth)<\/span> {<\/span>
                                            \n if<\/span> (<\/span>depth ><\/span> MAX_DEPTH)<\/span> {<\/span>
                                            \n throw<\/span> new<\/span> StackOverflowError<\/span>(<\/span>"\u9636\u4e58\u9012\u5f52\u8d85\u9650"<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n if<\/span> (<\/span>n <=<\/span> 1<\/span>)<\/span> return<\/span> 1<\/span>;<\/span>
                                            \n return<\/span> n *<\/span> factorialInternal<\/span>(<\/span>n –<\/span> 1<\/span>,<\/span> depth +<\/span> 1<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            private<\/span> static<\/span> long<\/span> product<\/span>(<\/span>int<\/span> start,<\/span> int<\/span> end)<\/span> {<\/span>
                                            \n long<\/span> result =<\/span> 1<\/span>;<\/span>
                                            \n for<\/span> (<\/span>int<\/span> i =<\/span> start;<\/span> i <=<\/span> end;<\/span> i++<\/span>)<\/span> {<\/span>
                                            \n result *=<\/span> i;<\/span>
                                            \n }<\/span>
                                            \n return<\/span> result;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/**
                                            \n * \u793a\u4f8b2：\u5b89\u5168\u4e8c\u53c9\u6811\u904d\u5386
                                            \n *\/<\/span>
                                            \n static<\/span> class<\/span> TreeNode<\/span> {<\/span>
                                            \n int<\/span> val;<\/span>
                                            \n TreeNode<\/span> left,<\/span> right;<\/span><\/p>\n

                                            public<\/span> void<\/span> traverseSafe<\/span>(<\/span>int<\/span> maxDepth)<\/span> {<\/span>
                                            \n traverseInternal<\/span>(<\/span>this<\/span>,<\/span> 0<\/span>,<\/span> maxDepth)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            private<\/span> void<\/span> traverseInternal<\/span>(<\/span>TreeNode<\/span> node,<\/span> int<\/span> depth,<\/span> int<\/span> maxDepth)<\/span> {<\/span>
                                            \n if<\/span> (<\/span>node ==<\/span> null<\/span>)<\/span> return<\/span>;<\/span>
                                            \n if<\/span> (<\/span>depth ><\/span> maxDepth)<\/span> {<\/span>
                                            \n \/\/ \u6df1\u5ea6\u8d85\u9650 \u2192 \u6539\u7528\u8fed\u4ee3\u904d\u5386\u5b50\u6811<\/span>
                                            \n iterativeTraverse<\/span>(<\/span>node)<\/span>;<\/span>
                                            \n return<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>node.<\/span>val)<\/span>;<\/span>
                                            \n traverseInternal<\/span>(<\/span>node.<\/span>left,<\/span> depth +<\/span> 1<\/span>,<\/span> maxDepth)<\/span>;<\/span>
                                            \n traverseInternal<\/span>(<\/span>node.<\/span>right,<\/span> depth +<\/span> 1<\/span>,<\/span> maxDepth)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            private<\/span> void<\/span> iterativeTraverse<\/span>(<\/span>TreeNode<\/span> root)<\/span> {<\/span>
                                            \n java.<\/span>util.<\/span><\/span>Stack<\/span><<\/span>TreeNode<\/span>><\/span><\/span> stack =<\/span> new<\/span> java.<\/span>util.<\/span><\/span>Stack<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                            \n stack.<\/span>push<\/span>(<\/span>root)<\/span>;<\/span>
                                            \n while<\/span> (<\/span>!<\/span>stack.<\/span>isEmpty<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                            \n TreeNode<\/span> node =<\/span> stack.<\/span>pop<\/span>(<\/span>)<\/span>;<\/span>
                                            \n if<\/span> (<\/span>node !=<\/span> null<\/span>)<\/span> {<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"[\u8fed\u4ee3]"<\/span> +<\/span> node.<\/span>val)<\/span>;<\/span>
                                            \n stack.<\/span>push<\/span>(<\/span>node.<\/span>right)<\/span>;<\/span>
                                            \n stack.<\/span>push<\/span>(<\/span>node.<\/span>left)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n }<\/span>
                                            \n }<\/span>
                                            \n }<\/span><\/p>\n

                                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                            \n \/\/ \u6d4b\u8bd5\u8d85\u5927\u9636\u4e58（\u81ea\u52a8\u964d\u7ea7\u4e3a\u8fed\u4ee3）<\/span>
                                            \n try<\/span> {<\/span>
                                            \n long<\/span> result =<\/span> safeFactorial<\/span>(<\/span>50000<\/span>)<\/span>;<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u5b89\u5168\u9636\u4e58\u8ba1\u7b97\u5b8c\u6210"<\/span>)<\/span>;<\/span>
                                            \n }<\/span> catch<\/span> (<\/span>StackOverflowError<\/span> e)<\/span> {<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u89e6\u53d1\u964d\u7ea7\u7b56\u7565: "<\/span> +<\/span> e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/\/ \u6d4b\u8bd5\u6811\u904d\u5386（\u9012\u5f52+\u8fed\u4ee3\u6df7\u5408）<\/span>
                                            \n TreeNode<\/span> root =<\/span> new<\/span> TreeNode<\/span>(<\/span>)<\/span>;<\/span>
                                            \n root.<\/span>traverseSafe<\/span>(<\/span>1000<\/span>)<\/span>;<\/span> \/\/ \u6df1\u5ea6\u8d85\u8fc71000\u81ea\u52a8\u5207\u8fed\u4ee3<\/span>
                                            \n }<\/span>
                                            \n}<\/span><\/p>\n

                                            \n
                                            \u2705 \u65b9\u6848\u56db：\u7ebf\u7a0b\u6c60 + \u4efb\u52a1\u62c6\u5206（\u7ec8\u6781\u65b9\u6848）<\/h5>\n

                                            \u9002\u7528\u4e8e：\u8d85\u5927\u9012\u5f52\u4efb\u52a1 + \u9700\u8981\u8d44\u6e90\u9694\u79bb\u7684\u751f\u4ea7\u73af\u5883<\/p>\n

                                            package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                            import<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>*<\/span>;<\/span>
                                            \nimport<\/span> java.<\/span>util.<\/span><\/span>ArrayList<\/span>;<\/span>
                                            \nimport<\/span> java.<\/span>util.<\/span><\/span>List<\/span>;<\/span><\/p>\n

                                            \/**
                                            \n * \u89e3\u51b3\u65b9\u68484：\u7ebf\u7a0b\u6c60\u5316\u9012\u5f52 – \u6808\u7a7a\u95f4\u9694\u79bb
                                            \n * \u539f\u7406：\u6bcf\u4e2a\u9012\u5f52\u5206\u652f\u5206\u914d\u72ec\u7acb\u7ebf\u7a0b，\u4e92\u4e0d\u5f71\u54cd\u7684\u6808\u7a7a\u95f4
                                            \n *\/<\/span>
                                            \npublic<\/span> class<\/span> StackOOM_Fix4_ThreadPool<\/span> {<\/span><\/p>\n

                                            private<\/span> static<\/span> final<\/span> ForkJoinPool<\/span> FORK_JOIN_POOL =<\/span>
                                            \n new<\/span> ForkJoinPool<\/span>(<\/span>Runtime<\/span>.<\/span>getRuntime<\/span>(<\/span>)<\/span>.<\/span>availableProcessors<\/span>(<\/span>)<\/span>)<\/span>;<\/span><\/p>\n

                                            \/**
                                            \n * \u4f7f\u7528ForkJoinPool\u5b9e\u73b0\u5e76\u884c\u9012\u5f52
                                            \n *\/<\/span>
                                            \n static<\/span> class<\/span> RecursiveSumTask<\/span> extends<\/span> RecursiveTask<\/span><<\/span>Long<\/span>><\/span><\/span> {<\/span>
                                            \n private<\/span> static<\/span> final<\/span> int<\/span> THRESHOLD =<\/span> 10000<\/span>;<\/span> \/\/ \u62c6\u5206\u9608\u503c<\/span>
                                            \n private<\/span> final<\/span> int<\/span>[<\/span>]<\/span> array;<\/span>
                                            \n private<\/span> final<\/span> int<\/span> start,<\/span> end;<\/span><\/p>\n

                                            public<\/span> RecursiveSumTask<\/span>(<\/span>int<\/span>[<\/span>]<\/span> array,<\/span> int<\/span> start,<\/span> int<\/span> end)<\/span> {<\/span>
                                            \n this<\/span>.<\/span>array =<\/span> array;<\/span>
                                            \n this<\/span>.<\/span>start =<\/span> start;<\/span>
                                            \n this<\/span>.<\/span>end =<\/span> end;<\/span>
                                            \n }<\/span><\/p>\n

                                            @Override<\/span>
                                            \n protected<\/span> Long<\/span> compute<\/span>(<\/span>)<\/span> {<\/span>
                                            \n int<\/span> length =<\/span> end –<\/span> start;<\/span><\/p>\n

                                            \/\/ \u5c0f\u4efb\u52a1\u76f4\u63a5\u8ba1\u7b97（\u65e0\u9012\u5f52）<\/span>
                                            \n if<\/span> (<\/span>length <=<\/span> THRESHOLD)<\/span> {<\/span>
                                            \n long<\/span> sum =<\/span> 0<\/span>;<\/span>
                                            \n for<\/span> (<\/span>int<\/span> i =<\/span> start;<\/span> i <<\/span> end;<\/span> i++<\/span>)<\/span> {<\/span>
                                            \n sum +=<\/span> array[<\/span>i]<\/span>;<\/span>
                                            \n }<\/span>
                                            \n return<\/span> sum;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/\/ \u5927\u4efb\u52a1\u62c6\u5206（\u5206\u6cbb，\u65e0\u6df1\u5ea6\u9012\u5f52）<\/span>
                                            \n int<\/span> mid =<\/span> start +<\/span> length \/<\/span> 2<\/span>;<\/span>
                                            \n RecursiveSumTask<\/span> leftTask =<\/span> new<\/span> RecursiveSumTask<\/span>(<\/span>array,<\/span> start,<\/span> mid)<\/span>;<\/span>
                                            \n RecursiveSumTask<\/span> rightTask =<\/span> new<\/span> RecursiveSumTask<\/span>(<\/span>array,<\/span> mid,<\/span> end)<\/span>;<\/span><\/p>\n

                                            \/\/ \u5f02\u6b65\u6267\u884c\u5b50\u4efb\u52a1<\/span>
                                            \n leftTask.<\/span>fork<\/span>(<\/span>)<\/span>;<\/span>
                                            \n rightTask.<\/span>fork<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                            \/\/ \u7b49\u5f85\u7ed3\u679c<\/span>
                                            \n return<\/span> leftTask.<\/span>join<\/span>(<\/span>)<\/span> +<\/span> rightTask.<\/span>join<\/span>(<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n }<\/span><\/p>\n

                                            \/**
                                            \n * \u81ea\u5b9a\u4e49\u7ebf\u7a0b\u6c60 + Callable（\u624b\u52a8\u63a7\u5236\u6808\u6df1\u5ea6）
                                            \n *\/<\/span>
                                            \n public<\/span> static<\/span> class<\/span> StackSafeExecutor<\/span> {<\/span>
                                            \n private<\/span> final<\/span> ExecutorService<\/span> executor;<\/span>
                                            \n private<\/span> final<\/span> int<\/span> maxDepthPerThread;<\/span><\/p>\n

                                            public<\/span> StackSafeExecutor<\/span>(<\/span>int<\/span> maxDepthPerThread)<\/span> {<\/span>
                                            \n this<\/span>.<\/span>maxDepthPerThread =<\/span> maxDepthPerThread;<\/span>
                                            \n this<\/span>.<\/span>executor =<\/span> Executors<\/span>.<\/span>newCachedThreadPool<\/span>(<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/**
                                            \n * \u5728\u72ec\u7acb\u7ebf\u7a0b\u4e2d\u6267\u884c\u9012\u5f52\u4efb\u52a1
                                            \n *\/<\/span>
                                            \n public<\/span> <<\/span>T<\/span>><\/span><\/span> Future<\/span><<\/span>T<\/span>><\/span><\/span> submitRecursive<\/span>(<\/span>Callable<\/span><<\/span>T<\/span>><\/span><\/span> recursiveTask)<\/span> {<\/span>
                                            \n \/\/ \u6bcf\u4e2a\u4efb\u52a1\u72ec\u7acb\u7ebf\u7a0b \u2192 \u72ec\u7acb\u7684\u6808\u7a7a\u95f4<\/span>
                                            \n return<\/span> executor.<\/span>submit<\/span>(<\/span>(<\/span>)<\/span> -><\/span> {<\/span>
                                            \n \/\/ \u8bbe\u7f6e\u7ebf\u7a0b\u6808\u9650\u5236（\u901a\u8fc7SecurityManager\u6a21\u62df）<\/span>
                                            \n Thread<\/span> currentThread =<\/span> Thread<\/span>.<\/span>currentThread<\/span>(<\/span>)<\/span>;<\/span>
                                            \n String<\/span> originalName =<\/span> currentThread.<\/span>getName<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                            try<\/span> {<\/span>
                                            \n currentThread.<\/span>setName<\/span>(<\/span>"RecursiveWorker-"<\/span> +<\/span> maxDepthPerThread)<\/span>;<\/span>
                                            \n return<\/span> recursiveTask.<\/span>call<\/span>(<\/span>)<\/span>;<\/span>
                                            \n }<\/span> finally<\/span> {<\/span>
                                            \n currentThread.<\/span>setName<\/span>(<\/span>originalName)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n }<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            public<\/span> void<\/span> shutdown<\/span>(<\/span>)<\/span> {<\/span>
                                            \n executor.<\/span>shutdown<\/span>(<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n }<\/span><\/p>\n

                                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> Exception<\/span> {<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"========== \u7ebf\u7a0b\u6c60\u9012\u5f52\u65b9\u6848 =========="<\/span>)<\/span>;<\/span><\/p>\n

                                            \/\/ 1. ForkJoin\u793a\u4f8b<\/span>
                                            \n int<\/span>[<\/span>]<\/span> bigArray =<\/span> new<\/span> int<\/span>[<\/span>100_000_000<\/span>]<\/span>;<\/span>
                                            \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> bigArray.<\/span>length;<\/span> i++<\/span>)<\/span> {<\/span>
                                            \n bigArray[<\/span>i]<\/span> =<\/span> i %<\/span> 10<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            RecursiveSumTask<\/span> task =<\/span> new<\/span> RecursiveSumTask<\/span>(<\/span>bigArray,<\/span> 0<\/span>,<\/span> bigArray.<\/span>length)<\/span>;<\/span>
                                            \n Long<\/span> result =<\/span> FORK_JOIN_POOL.<\/span>invoke<\/span>(<\/span>task)<\/span>;<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"ForkJoin\u8ba1\u7b97\u7ed3\u679c: %d%n"<\/span>,<\/span> result)<\/span>;<\/span><\/p>\n

                                            \/\/ 2. \u7ebf\u7a0b\u6c60\u9694\u79bb\u793a\u4f8b<\/span>
                                            \n StackSafeExecutor<\/span> executor =<\/span> new<\/span> StackSafeExecutor<\/span>(<\/span>5000<\/span>)<\/span>;<\/span>
                                            \n List<\/span><<\/span>Future<\/span><<\/span>Long<\/span>><\/span>><\/span><\/span> futures =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                            for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 10<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>
                                            \n final<\/span> int<\/span> taskId =<\/span> i;<\/span>
                                            \n Future<\/span><<\/span>Long<\/span>><\/span><\/span> future =<\/span> executor.<\/span>submitRecursive<\/span>(<\/span>(<\/span>)<\/span> -><\/span> {<\/span>
                                            \n \/\/ \u6bcf\u4e2a\u7ebf\u7a0b\u72ec\u7acb\u6808，\u4e92\u4e0d\u5f71\u54cd<\/span>
                                            \n long<\/span> sum =<\/span> 0<\/span>;<\/span>
                                            \n for<\/span> (<\/span>int<\/span> j =<\/span> 0<\/span>;<\/span> j <<\/span> 1_000_000<\/span>;<\/span> j++<\/span>)<\/span> {<\/span>
                                            \n sum +=<\/span> j;<\/span>
                                            \n }<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u4efb\u52a1%d\u5b8c\u6210, \u7ebf\u7a0b: %s%n"<\/span>,<\/span>
                                            \n taskId,<\/span> Thread<\/span>.<\/span>currentThread<\/span>(<\/span>)<\/span>.<\/span>getName<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                            \n return<\/span> sum;<\/span>
                                            \n }<\/span>)<\/span>;<\/span>
                                            \n futures.<\/span>add<\/span>(<\/span>future)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/\/ \u7b49\u5f85\u6240\u6709\u4efb\u52a1\u5b8c\u6210<\/span>
                                            \n for<\/span> (<\/span>Future<\/span><<\/span>Long<\/span>><\/span><\/span> future :<\/span> futures)<\/span> {<\/span>
                                            \n future.<\/span>get<\/span>(<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            executor.<\/span>shutdown<\/span>(<\/span>)<\/span>;<\/span>
                                            \n FORK_JOIN_POOL.<\/span>shutdown<\/span>(<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n}<\/span><\/p>\n

                                            \n

                                            3.5 \u65b9\u6848\u5bf9\u6bd4\u4e0e\u9009\u578b\u5efa\u8bae<\/h4>\n\n\u5bf9\u6bd4\u7ef4\u5ea6\u65b9\u68481 \u8fed\u4ee3\u65b9\u68482 \u5c3e\u9012\u5f52\u65b9\u68483 \u53d7\u63a7\u9012\u5f52\u65b9\u68484 \u7ebf\u7a0b\u6c60<\/tr>\n\n\n\n\n\n\n
                                            \u6808\u5b89\u5168\u6027<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50 \u7edd\u5bf9\u5b89\u5168<\/td>\n\u2b50\u2b50 \u9700\u8bed\u8a00\u652f\u6301<\/td>\n\u2b50\u2b50\u2b50\u2b50 \u53ef\u63a7<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50 \u9694\u79bb\u5b89\u5168<\/td>\n<\/tr>\n
                                            \u4ee3\u7801\u6539\u52a8<\/td>\n\u91cd\u6784\u8f83\u5927<\/td>\n\u4e2d\u7b49<\/td>\n\u5c0f<\/td>\n\u8f83\u5927<\/td>\n<\/tr>\n
                                            \u6027\u80fd<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50 \u6700\u5feb<\/td>\n\u2b50\u2b50\u2b50 \u6709\u5f00\u9500<\/td>\n\u2b50\u2b50\u2b50 \u4e2d\u7b49<\/td>\n\u2b50\u2b50 \u7ebf\u7a0b\u5207\u6362<\/td>\n<\/tr>\n
                                            \u53ef\u8bfb\u6027<\/td>\n\u2b50\u2b50\u2b50 \u4e00\u822c<\/td>\n\u2b50\u2b50 \u590d\u6742<\/td>\n\u2b50\u2b50\u2b50\u2b50 \u6e05\u6670<\/td>\n\u2b50\u2b50\u2b50 \u6e05\u6670<\/td>\n<\/tr>\n
                                            \u9002\u7528\u573a\u666f<\/td>\n\u6240\u6709\u5faa\u73af\u573a\u666f<\/td>\n\u51fd\u6570\u5f0f\u7f16\u7a0b<\/td>\n\u6811\/\u56fe\u904d\u5386<\/td>\n\u8d85\u5927\u89c4\u6a21\u4efb\u52a1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                                            \u9009\u578b\u51b3\u7b56\u6811：<\/p>\n

                                            \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                            \n \u2502 \u9047\u5230\u6808\u6ea2\u51fa \u2502
                                            \n \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                            \n \u2193
                                            \n \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                            \n \u2502 \u2502
                                            \n \u250c\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2510
                                            \n \u2502 \u80fd\u5426\u6539\u4e3a \u2502 \u662f \u2502 \u5fc5\u987b\u4fdd\u7559 \u2502
                                            \n \u2502 \u8fed\u4ee3\u5b9e\u73b0？ \u2502 \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2192 \u2502 \u9012\u5f52\u8bed\u4e49 \u2502
                                            \n \u2514\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2518
                                            \n \u2502 \u5426 \u2502
                                            \n \u2193 \u2193
                                            \n \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                            \n \u2502 \u6dfb\u52a0\u6df1\u5ea6\u9650\u5236 \u2502 \u2502 \u5206\u6cbb \/ \u7ebf\u7a0b\u6c60 \u2502
                                            \n \u2502 + \u964d\u7ea7\u7b56\u7565 \u2502 \u2502 \u6808\u7a7a\u95f4\u9694\u79bb \u2502
                                            \n \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/p>\n

                                            \n

                                            3.6 \u9884\u9632\u63aa\u65bd\u4e0e\u7f16\u7801\u89c4\u8303<\/h4>\n

                                            \/**
                                            \n * \u9012\u5f52\u4ee3\u7801\u89c4\u8303\u68c0\u67e5\u6e05\u5355
                                            \n *\/<\/span>
                                            \npublic<\/span> class<\/span> RecursionGuard<\/span> {<\/span><\/p>\n

                                            \/\/ \u274c \u9519\u8bef\u793a\u4f8b1：\u65e0\u7ec8\u6b62\u6761\u4ef6<\/span>
                                            \n public<\/span> void<\/span> badRecursion1<\/span>(<\/span>)<\/span> {<\/span>
                                            \n badRecursion1<\/span>(<\/span>)<\/span>;<\/span> \/\/ \u81f4\u547d！<\/span>
                                            \n }<\/span><\/p>\n

                                            \/\/ \u274c \u9519\u8bef\u793a\u4f8b2：\u7ec8\u6b62\u6761\u4ef6\u6c38\u8fdc\u4e0d\u6ee1\u8db3<\/span>
                                            \n public<\/span> void<\/span> badRecursion2<\/span>(<\/span>int<\/span> n)<\/span> {<\/span>
                                            \n if<\/span> (<\/span>n ><\/span> 0<\/span>)<\/span> {<\/span> \/\/ n \u4ece\u672a\u51cf\u5c11<\/span>
                                            \n badRecursion2<\/span>(<\/span>n)<\/span>;<\/span> \/\/ \u81f4\u547d！<\/span>
                                            \n }<\/span>
                                            \n }<\/span><\/p>\n

                                            \/\/ \u274c \u9519\u8bef\u793a\u4f8b3：\u9012\u5f52\u5728return\u4e4b\u540e<\/span>
                                            \n public<\/span> void<\/span> badRecursion3<\/span>(<\/span>int<\/span> n)<\/span> {<\/span>
                                            \n badRecursion3<\/span>(<\/span>n –<\/span> 1<\/span>)<\/span>;<\/span> \/\/ \u5e94\u5148\u5224\u65ad\u7ec8\u6b62\u6761\u4ef6<\/span>
                                            \n if<\/span> (<\/span>n <=<\/span> 0<\/span>)<\/span> return<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/\/ \u2705 \u6b63\u786e\u793a\u4f8b：\u5148\u5224\u65ad\u7ec8\u6b62，\u518d\u9012\u5f52<\/span>
                                            \n public<\/span> void<\/span> goodRecursion<\/span>(<\/span>int<\/span> n)<\/span> {<\/span>
                                            \n if<\/span> (<\/span>n <=<\/span> 0<\/span>)<\/span> return<\/span>;<\/span> \/\/ 1. \u7ec8\u6b62\u6761\u4ef6\u4f18\u5148<\/span>
                                            \n \/\/ 2. \u4e1a\u52a1\u903b\u8f91<\/span>
                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>n)<\/span>;<\/span>
                                            \n \/\/ 3. \u9012\u5f52\u8c03\u7528（\u89c4\u6a21\u51cf\u5c0f）<\/span>
                                            \n goodRecursion<\/span>(<\/span>n –<\/span> 1<\/span>)<\/span>;<\/span>
                                            \n }<\/span><\/p>\n

                                            \/\/ \u2705 \u9632\u5fa1\u6027\u7f16\u7a0b：\u6df1\u5ea6\u5b88\u536b<\/span>
                                            \n public<\/span> void<\/span> safeRecursion<\/span>(<\/span>int<\/span> n,<\/span> int<\/span> depth)<\/span> {<\/span>
                                            \n int<\/span> MAX_DEPTH =<\/span> 1000<\/span>;<\/span>
                                            \n if<\/span> (<\/span>depth ><\/span> MAX_DEPTH)<\/span> {<\/span>
                                            \n throw<\/span> new<\/span> RuntimeException<\/span>(<\/span>"\u9012\u5f52\u6df1\u5ea6\u8d85\u9650: "<\/span> +<\/span> depth)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n if<\/span> (<\/span>n <=<\/span> 0<\/span>)<\/span> return<\/span>;<\/span>
                                            \n safeRecursion<\/span>(<\/span>n –<\/span> 1<\/span>,<\/span> depth +<\/span> 1<\/span>)<\/span>;<\/span>
                                            \n }<\/span>
                                            \n}<\/span><\/p>\n

                                            \n

                                            3.7 \u9762\u8bd5\u9ad8\u9891\u9898<\/h4>\n

                                            Q1：\u9012\u5f52\u4e00\u5b9a\u4f1a\u6808\u6ea2\u51fa\u5417？<\/p>\n

                                            \u4e0d\u4e00\u5b9a\u3002\u53ea\u8981\u9012\u5f52\u6df1\u5ea6 < \u6808\u5bb9\u91cf\u5c31\u4e0d\u4f1a\u6ea2\u51fa\u3002\u4f46\u9ed8\u8ba41MB\u6808 \u2248 50000\u5c42\u9012\u5f52，\u4e1a\u52a1\u573a\u666f\u901a\u5e38\u53ef\u63a7\u3002<\/p>\n

                                            Q2：\u4e3a\u4ec0\u4e48\u5c3e\u9012\u5f52\u4f18\u5316\u5728Java\u4e2d\u65e0\u6548？<\/p>\n

                                            JVM\u6ca1\u6709\u5b9e\u73b0\u5c3e\u8c03\u7528\u6d88\u9664（TCO），\u56e0\u4e3a\u5b89\u5168\u7b56\u7565（\u9700\u8981\u4fdd\u7559\u6808\u5e27\u8bbf\u95ee\u6743\u9650）\u548c\u5e73\u53f0\u65e0\u5173\u6027\u8003\u8651\u3002<\/p>\n

                                            Q3：\u6808\u6ea2\u51fa\u548c\u5806\u6ea2\u51fa\u7684\u533a\u522b？<\/p>\n

                                              \n
                                            • \u6808\u6ea2\u51fa：\u65b9\u6cd5\u8c03\u7528\u5c42\u6570\u8fc7\u591a，\u6bcf\u4e2a\u7ebf\u7a0b\u72ec\u7acb\u6808<\/li>\n
                                            • \u5806\u6ea2\u51fa：\u5bf9\u8c61\u521b\u5efa\u8fc7\u591a，\u6240\u6709\u7ebf\u7a0b\u5171\u4eab\u5806<\/li>\n
                                            • \u6062\u590d\u80fd\u529b：\u6808\u6ea2\u51fa\u53ef\u6355\u83b7，\u5806\u6ea2\u51fa\u901a\u5e38\u81f4\u547d<\/li>\n<\/ul>\n

                                              Q4：-Xss\u8bbe\u7f6e\u591a\u5c11\u5408\u9002？<\/p>\n

                                                \n
                                              • \u9ed8\u8ba41MB（\u5927\u591a\u6570\u573a\u666f\u8db3\u591f）<\/li>\n
                                              • \u9012\u5f52\u6df1\u5ea6\u5927 \u2192 \u8c03\u5927\u6808（\u59822MB）<\/li>\n
                                              • \u5927\u91cf\u7ebf\u7a0b \u2192 \u8c03\u5c0f\u6808（\u5982256KB）<\/li>\n
                                              • \u8ba1\u7b97\u516c\u5f0f：\u6808\u5927\u5c0f \u2248 \u65b9\u6cd5\u5e27\u5927\u5c0f \u00d7 \u6700\u5927\u6df1\u5ea6<\/li>\n<\/ul>\n
                                                \n

                                                \u56db\u3001\u5b9e\u6218\u4e09：\u5143\u7a7a\u95f4\u6ea2\u51fa \u2014\u2014 \u52a8\u6001\u4ee3\u7406\u6cc4\u6f0f<\/h3>\n

                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                4.1 \u590d\u73b0\u4ee3\u7801（ByteBuddy\u7248\u672c）<\/h4>\n

                                                package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2<\/span>;<\/span><\/p>\n

                                                import<\/span> net.<\/span>bytebuddy.<\/span><\/span>ByteBuddy<\/span>;<\/span>
                                                \nimport<\/span> net.<\/span>bytebuddy.<\/span>dynamic.<\/span>loading.<\/span><\/span>ClassLoadingStrategy<\/span>;<\/span>
                                                \nimport<\/span> java.<\/span>lang.<\/span>management.<\/span><\/span>ManagementFactory<\/span>;<\/span>
                                                \nimport<\/span> java.<\/span>util.<\/span><\/span>ArrayList<\/span>;<\/span>
                                                \nimport<\/span> java.<\/span>util.<\/span><\/span>List<\/span>;<\/span><\/p>\n

                                                \/**
                                                \n * \u573a\u666f：\u65e0\u9650\u751f\u6210\u52a8\u6001\u4ee3\u7406\u7c7b，\u8017\u5c3d\u5143\u7a7a\u95f4
                                                \n *
                                                \n * \u5143\u7a7a\u95f4（Metaspace）\u5b58\u50a8：
                                                \n * 1. \u7c7b\u7684\u5143\u6570\u636e（\u540d\u79f0\u3001\u8bbf\u95ee\u4fee\u9970\u7b26\u3001\u7236\u7c7b\u3001\u63a5\u53e3\u7b49）
                                                \n * 2. \u65b9\u6cd5\u5b57\u8282\u7801
                                                \n * 3. \u5e38\u91cf\u6c60
                                                \n * 4. \u6ce8\u89e3\u4fe1\u606f
                                                \n * 5. \u5373\u65f6\u7f16\u8bd1（JIT）\u540e\u7684\u4ee3\u7801\u7f13\u5b58
                                                \n *
                                                \n * JVM\u53c2\u6570：-XX:MaxMetaspaceSize=64m -XX:+PrintGCDetails
                                                \n *\/<\/span>
                                                \npublic<\/span> class<\/span> MetaspaceOOM_ByteBuddy<\/span> {<\/span><\/p>\n

                                                public<\/span> static<\/span> class<\/span> TargetClass<\/span> {<\/span>
                                                \n public<\/span> void<\/span> hello<\/span>(<\/span>)<\/span> {<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"Hello from Target"<\/span>)<\/span>;<\/span>
                                                \n }<\/span>
                                                \n }<\/span><\/p>\n

                                                public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"========== \u5143\u7a7a\u95f4\u6ea2\u51fa\u6a21\u62df =========="<\/span>)<\/span>;<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5143\u7a7a\u95f4\u9650\u5236: -XX:MaxMetaspaceSize=64m%n"<\/span>)<\/span>;<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u521d\u59cb\u7c7b\u52a0\u8f7d\u6570\u91cf: %d%n"<\/span>,<\/span>
                                                \n ManagementFactory<\/span>.<\/span>getClassLoadingMXBean<\/span>(<\/span>)<\/span>.<\/span>getLoadedClassCount<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"———————————–"<\/span>)<\/span>;<\/span><\/p>\n

                                                ByteBuddy<\/span> byteBuddy =<\/span> new<\/span> ByteBuddy<\/span>(<\/span>)<\/span>;<\/span>
                                                \n List<\/span><<\/span>Class<\/span><<\/span>?<\/span>><\/span>><\/span><\/span> classes =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span> \/\/ \u6301\u6709\u5f15\u7528，\u9632\u6b62GC\u5378\u8f7d<\/span>
                                                \n int<\/span> counter =<\/span> 0<\/span>;<\/span><\/p>\n

                                                try<\/span> {<\/span>
                                                \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                                \n \/\/ \u52a8\u6001\u751f\u6210\u5b50\u7c7b，\u6bcf\u4e2a\u7c7b\u540d\u552f\u4e00<\/span>
                                                \n Class<\/span><<\/span>?<\/span>><\/span><\/span> dynamicClass =<\/span> byteBuddy
                                                \n .<\/span>subclass<\/span>(<\/span>TargetClass<\/span>.<\/span>class<\/span>)<\/span>
                                                \n .<\/span>name<\/span>(<\/span>"com.example.aliyunDemo.test.jvm2.GeneratedClass_"<\/span> +<\/span> counter++<\/span>)<\/span>
                                                \n .<\/span>make<\/span>(<\/span>)<\/span>
                                                \n .<\/span>load<\/span>(<\/span>MetaspaceOOM_ByteBuddy<\/span>.<\/span>class<\/span>.<\/span>getClassLoader<\/span>(<\/span>)<\/span>,<\/span>
                                                \n ClassLoadingStrategy.<\/span>Default<\/span>.<\/span>WRAPPER)<\/span>
                                                \n .<\/span>getLoaded<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                classes.<\/span>add<\/span>(<\/span>dynamicClass)<\/span>;<\/span> \/\/ \u5f3a\u5f15\u7528，\u9632\u6b62\u88ab\u56de\u6536<\/span><\/p>\n

                                                if<\/span> (<\/span>counter %<\/span> 500<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                \n ClassLoadingMXBean<\/span> classLoaderBean =<\/span> ManagementFactory<\/span>.<\/span>getClassLoadingMXBean<\/span>(<\/span>)<\/span>;<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5df2\u751f\u6210\u7c7b: %6d | \u5df2\u52a0\u8f7d\u7c7b\u603b\u6570: %6d | \u5f53\u524d\u52a0\u8f7d\u7c7b: %6d%n"<\/span>,<\/span>
                                                \n counter,<\/span>
                                                \n classLoaderBean.<\/span>getTotalLoadedClassCount<\/span>(<\/span>)<\/span>,<\/span>
                                                \n classLoaderBean.<\/span>getLoadedClassCount<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                \n }<\/span>
                                                \n }<\/span>
                                                \n }<\/span> catch<\/span> (<\/span>OutOfMemoryError<\/span> e)<\/span> {<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\\\\n========== \u5143\u7a7a\u95f4\u6ea2\u51fa\u6355\u83b7 =========="<\/span>)<\/span>;<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u6700\u7ec8\u751f\u6210\u7c7b\u6570: %d%n"<\/span>,<\/span> counter)<\/span>;<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u9519\u8bef\u7c7b\u578b: %s%n"<\/span>,<\/span> e.<\/span>getClass<\/span>(<\/span>)<\/span>.<\/span>getSimpleName<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u9519\u8bef\u4fe1\u606f: %s%n"<\/span>,<\/span> e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span><\/p>\n

                                                \/\/ \u5143\u7a7a\u95f4\u4f7f\u7528\u60c5\u51b5<\/span>
                                                \n for<\/span> (<\/span>MemoryPoolMXBean<\/span> pool :<\/span> ManagementFactory<\/span>.<\/span>getMemoryPoolMXBeans<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                                \n if<\/span> (<\/span>pool.<\/span>getName<\/span>(<\/span>)<\/span>.<\/span>contains<\/span>(<\/span>"Metaspace"<\/span>)<\/span>)<\/span> {<\/span>
                                                \n MemoryUsage<\/span> usage =<\/span> pool.<\/span>getUsage<\/span>(<\/span>)<\/span>;<\/span>
                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5143\u7a7a\u95f4\u4f7f\u7528: %dMB \/ %dMB%n"<\/span>,<\/span>
                                                \n usage.<\/span>getUsed<\/span>(<\/span>)<\/span> \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>,<\/span>
                                                \n usage.<\/span>getMax<\/span>(<\/span>)<\/span> \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span>
                                                \n }<\/span>
                                                \n }<\/span>
                                                \n e.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>
                                                \n }<\/span>
                                                \n }<\/span>
                                                \n}<\/span><\/p>\n

                                                \n

                                                4.2 JVM\u5143\u7a7a\u95f4\u6f14\u53d8\u56fe\u89e3<\/h4>\n

                                                \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                \n\u2502 \u5143\u7a7a\u95f4\u5185\u5b58\u5206\u914d\u8fc7\u7a0b \u2502
                                                \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                \n\u2502 \u9636\u6bb5 \u2502 \u751f\u6210\u7c7b\u6570\u91cf \u2502 \u5143\u7a7a\u95f4\u5360\u7528 \u2502 GC\u89e6\u53d1\u9891\u7387 \u2502
                                                \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                \n\u2502 0-20% \u2502 0 – 5000 \u2502 0-13MB \u2502 \u65e0GC \u2502
                                                \n\u2502 20-50% \u2502 5000 – 12000 \u2502 13-32MB \u2502 \u5076\u5c14Full GC\u2502
                                                \n\u2502 50-80% \u2502 12000 – 19000 \u2502 32-51MB \u2502 \u9891\u7e41Full GC\u2502
                                                \n\u2502 80-95% \u2502 19000 – 22000 \u2502 51-61MB \u2502 \u6301\u7eedFull GC\u2502
                                                \n\u2502 >95% \u2502 22000+ \u2502 >61MB \u2502 OOM\u5f02\u5e38 \u2502
                                                \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/p>\n

                                                \u5355\u52a8\u6001\u4ee3\u7406\u7c7b\u5185\u5b58\u6784\u6210：
                                                \n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                \n\u2502 \u7c7b\u5143\u6570\u636e (Class Metadata) ~5KB \u2502
                                                \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                \n\u2502 \u65b9\u6cd5\u5b57\u8282\u7801 (Method Bytecode) ~2KB \u2502
                                                \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                \n\u2502 \u5e38\u91cf\u6c60 (Constant Pool) ~1KB \u2502
                                                \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                \n\u2502 \u6ce8\u89e3\u4fe1\u606f (Annotations) ~0.5KB \u2502
                                                \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                \n\u2502 \u5176\u4ed6\u4fe1\u606f (Other) ~0.5KB \u2502
                                                \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                                \n\u2248 9KB\/\u7c7b \u00d7 22000\u7c7b \u2248 198MB (\u538b\u7f29\u540e\u224864MB)<\/p>\n

                                                \u5143\u7a7a\u95f4\u6ea2\u51fa\u4e09\u8981\u7d20：<\/p>\n

                                              • \u274c \u65e0\u7f13\u5b58\u590d\u7528 – \u6bcf\u4e2a\u8bf7\u6c42\u751f\u6210\u65b0\u7c7b<\/li>\n
                                              • \u274c \u7c7b\u52a0\u8f7d\u5668\u6cc4\u6f0f – \u81ea\u5b9a\u4e49\u7c7b\u52a0\u8f7d\u5668\u65e0\u6cd5\u56de\u6536<\/li>\n
                                              • \u274c \u5143\u7a7a\u95f4\u4e0a\u9650\u8fc7\u4f4e – MaxMetaspaceSize\u8bbe\u7f6e\u4e0d\u8db3<\/li>\n
                                                \n

                                                4.3 \u8fd0\u884c\u7ed3\u679c<\/h4>\n

                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                \u5173\u952e\u7ed3\u8bba：<\/p>\n

                                                  \n
                                                • \u2705 64MB\u5143\u7a7a\u95f4 \u2248 22000\u4e2a\u52a8\u6001\u4ee3\u7406\u7c7b<\/li>\n
                                                • \u2705 \u6bcf\u7c7b\u5e73\u5747\u5360\u7528 2.9KB（JVM\u538b\u7f29\u540e）<\/li>\n
                                                • \u2705 ClassLoader\u6301\u6709\u5f15\u7528\u662f\u56de\u6536\u5931\u8d25\u4e3b\u56e0<\/li>\n<\/ul>\n
                                                  \n

                                                  4.4 \u89e3\u51b3\u65b9\u6848<\/h4>\n

                                                  \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                  \u2705 \u65b9\u6848\u4e00：\u4ee3\u7406\u7c7b\u7f13\u5b58\u590d\u7528（\u9996\u9009）<\/h5>\n

                                                  \u9002\u7528\u4e8e：\u76ee\u6807\u7c7b\u6709\u9650\u4e14\u91cd\u590d\u4f7f\u7528\u7684\u573a\u666f<\/p>\n

                                                  package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                                  import<\/span> net.<\/span>bytebuddy.<\/span><\/span>ByteBuddy<\/span>;<\/span>
                                                  \nimport<\/span> net.<\/span>bytebuddy.<\/span>dynamic.<\/span>loading.<\/span><\/span>ClassLoadingStrategy<\/span>;<\/span>
                                                  \nimport<\/span> java.<\/span>util.<\/span><\/span>Map<\/span>;<\/span>
                                                  \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>ConcurrentHashMap<\/span>;<\/span><\/p>\n

                                                  \/**
                                                  \n * \u89e3\u51b3\u65b9\u68481：\u4ee3\u7406\u7c7b\u7f13\u5b58\u6c60
                                                  \n * \u539f\u7406：\u540c\u4e00\u4e2a\u76ee\u6807\u7c7b\u53ea\u751f\u6210\u4e00\u6b21\u4ee3\u7406，\u6c38\u4e45\u590d\u7528
                                                  \n *\/<\/span>
                                                  \npublic<\/span> class<\/span> MetaspaceOOM_Fix1_Cache<\/span> {<\/span><\/p>\n

                                                  \/\/ \u4ee3\u7406\u7c7b\u7f13\u5b58（\u76ee\u6807\u7c7b \u2192 \u4ee3\u7406\u7c7b）<\/span>
                                                  \n private<\/span> static<\/span> final<\/span> Map<\/span><<\/span>Class<\/span><<\/span>?<\/span>><\/span>,<\/span> Class<\/span><<\/span>?<\/span>><\/span>><\/span><\/span> PROXY_CACHE =<\/span> new<\/span> ConcurrentHashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                                  \n private<\/span> static<\/span> final<\/span> ByteBuddy<\/span> BYTE_BUDDY =<\/span> new<\/span> ByteBuddy<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                  \/**
                                                  \n * \u83b7\u53d6\u4ee3\u7406\u7c7b（\u7f13\u5b58\u7248\u672c）
                                                  \n *\/<\/span>
                                                  \n public<\/span> static<\/span> Class<\/span><<\/span>?<\/span>><\/span><\/span> getProxyClass<\/span>(<\/span>Class<\/span><<\/span>?<\/span>><\/span><\/span> targetClass)<\/span> {<\/span>
                                                  \n return<\/span> PROXY_CACHE.<\/span>computeIfAbsent<\/span>(<\/span>targetClass,<\/span> key -><\/span> {<\/span>
                                                  \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[\u7f13\u5b58] \u9996\u6b21\u751f\u6210\u4ee3\u7406\u7c7b: %s%n"<\/span>,<\/span> key.<\/span>getSimpleName<\/span>(<\/span>)<\/span>)<\/span>;<\/span><\/p>\n

                                                  \/\/ \u56fa\u5b9a\u4ee3\u7406\u7c7b\u540d\u79f0，\u907f\u514d\u4e0d\u65ad\u751f\u6210\u65b0\u7c7b\u540d<\/span>
                                                  \n String<\/span> proxyClassName =<\/span> key.<\/span>getName<\/span>(<\/span>)<\/span> +<\/span> "$$ByteBuddyProxy"<\/span>;<\/span><\/p>\n

                                                  return<\/span> BYTE_BUDDY
                                                  \n .<\/span>subclass<\/span>(<\/span>key)<\/span>
                                                  \n .<\/span>name<\/span>(<\/span>proxyClassName)<\/span> \/\/ \u56fa\u5b9a\u540d\u79f0<\/span>
                                                  \n .<\/span>make<\/span>(<\/span>)<\/span>
                                                  \n .<\/span>load<\/span>(<\/span>key.<\/span>getClassLoader<\/span>(<\/span>)<\/span>,<\/span>
                                                  \n ClassLoadingStrategy.<\/span>Default<\/span>.<\/span>WRAPPER)<\/span>
                                                  \n .<\/span>getLoaded<\/span>(<\/span>)<\/span>;<\/span>
                                                  \n }<\/span>)<\/span>;<\/span>
                                                  \n }<\/span><\/p>\n

                                                  \/**
                                                  \n * \u6e05\u7a7a\u7f13\u5b58（\u91cd\u65b0\u90e8\u7f72\u65f6\u8c03\u7528）
                                                  \n *\/<\/span>
                                                  \n public<\/span> static<\/span> void<\/span> clearCache<\/span>(<\/span>)<\/span> {<\/span>
                                                  \n PROXY_CACHE.<\/span>clear<\/span>(<\/span>)<\/span>;<\/span>
                                                  \n System<\/span>.<\/span>gc<\/span>(<\/span>)<\/span>;<\/span> \/\/ \u63d0\u793aGC\u56de\u6536\u7c7b<\/span>
                                                  \n }<\/span><\/p>\n

                                                  public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                  \n \/\/ \u6a21\u62df\u5e76\u53d1\u8bf7\u6c42<\/span>
                                                  \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 100000<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>
                                                  \n Class<\/span><<\/span>?<\/span>><\/span><\/span> proxy1 =<\/span> getProxyClass<\/span>(<\/span>TargetClass<\/span>.<\/span>class<\/span>)<\/span>;<\/span>
                                                  \n Class<\/span><<\/span>?<\/span>><\/span><\/span> proxy2 =<\/span> getProxyClass<\/span>(<\/span>TargetClass<\/span>.<\/span>class<\/span>)<\/span>;<\/span><\/p>\n

                                                  \/\/ \u9a8c\u8bc1：\u4e24\u6b21\u83b7\u53d6\u7684\u662f\u540c\u4e00\u4e2aClass\u5bf9\u8c61<\/span>
                                                  \n assert<\/span> proxy1 ==<\/span> proxy2 :<\/span> "\u7f13\u5b58\u5931\u6548"<\/span>;<\/span><\/p>\n

                                                  if<\/span> (<\/span>i %<\/span> 10000<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                  \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5f53\u524d\u4ee3\u7406\u7c7b: %s, \u7f13\u5b58\u547d\u4e2d: %d%n"<\/span>,<\/span>
                                                  \n proxy1.<\/span>getSimpleName<\/span>(<\/span>)<\/span>,<\/span> i)<\/span>;<\/span>
                                                  \n }<\/span>
                                                  \n }<\/span>
                                                  \n }<\/span><\/p>\n

                                                  public<\/span> static<\/span> class<\/span> TargetClass<\/span> {<\/span>}<\/span>
                                                  \n}<\/span><\/p>\n

                                                  \u4f18\u52bf：<\/p>\n

                                                    \n
                                                  • \u2705 \u96f6\u5185\u5b58\u6cc4\u6f0f – \u7c7b\u6570\u91cf\u6052\u5b9a<\/li>\n
                                                  • \u2705 \u9ad8\u6027\u80fd – \u907f\u514d\u91cd\u590d\u751f\u6210\u5b57\u8282\u7801<\/li>\n
                                                  • \u2705 \u7ebf\u7a0b\u5b89\u5168 – ConcurrentHashMap\u4fdd\u8bc1<\/li>\n<\/ul>\n
                                                    \n
                                                    \u2705 \u65b9\u6848\u4e8c：\u5f31\u5f15\u7528\u7f13\u5b58（\u81ea\u52a8\u56de\u6536）<\/h5>\n

                                                    \u9002\u7528\u4e8e：\u76ee\u6807\u7c7b\u52a8\u6001\u53d8\u5316，\u9700\u81ea\u52a8\u6e05\u7406\u7684\u573a\u666f<\/p>\n

                                                    package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                                    import<\/span> net.<\/span>bytebuddy.<\/span><\/span>ByteBuddy<\/span>;<\/span>
                                                    \nimport<\/span> net.<\/span>bytebuddy.<\/span>dynamic.<\/span>loading.<\/span><\/span>ClassLoadingStrategy<\/span>;<\/span>
                                                    \nimport<\/span> java.<\/span>lang.<\/span>ref.<\/span><\/span>WeakReference<\/span>;<\/span>
                                                    \nimport<\/span> java.<\/span>util.<\/span><\/span>Map<\/span>;<\/span>
                                                    \nimport<\/span> java.<\/span>util.<\/span><\/span>WeakHashMap<\/span>;<\/span><\/p>\n

                                                    \/**
                                                    \n * \u89e3\u51b3\u65b9\u68482：\u5f31\u5f15\u7528\u7f13\u5b58
                                                    \n * \u539f\u7406：WeakHashMap + WeakReference，GC\u65f6\u81ea\u52a8\u6e05\u7406
                                                    \n *\/<\/span>
                                                    \npublic<\/span> class<\/span> MetaspaceOOM_Fix2_WeakCache<\/span> {<\/span><\/p>\n

                                                    \/\/ \u5f31\u5f15\u7528\u7f13\u5b58：key\u548cvalue\u90fd\u662f\u5f31\u5f15\u7528<\/span>
                                                    \n private<\/span> static<\/span> final<\/span> Map<\/span><<\/span>Class<\/span><<\/span>?<\/span>><\/span>,<\/span> WeakReference<\/span><<\/span>Class<\/span><<\/span>?<\/span>><\/span>><\/span>><\/span><\/span> WEAK_CACHE =<\/span>
                                                    \n new<\/span> WeakHashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                                    \n private<\/span> static<\/span> final<\/span> ByteBuddy<\/span> BYTE_BUDDY =<\/span> new<\/span> ByteBuddy<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                    \/**
                                                    \n * \u83b7\u53d6\u4ee3\u7406\u7c7b（\u5f31\u5f15\u7528\u7248\u672c）
                                                    \n *\/<\/span>
                                                    \n public<\/span> static<\/span> Class<\/span><<\/span>?<\/span>><\/span><\/span> getProxyClass<\/span>(<\/span>Class<\/span><<\/span>?<\/span>><\/span><\/span> targetClass)<\/span> {<\/span>
                                                    \n synchronized<\/span> (<\/span>WEAK_CACHE)<\/span> {<\/span>
                                                    \n WeakReference<\/span><<\/span>Class<\/span><<\/span>?<\/span>><\/span>><\/span><\/span> ref =<\/span> WEAK_CACHE.<\/span>get<\/span>(<\/span>targetClass)<\/span>;<\/span>
                                                    \n Class<\/span><<\/span>?<\/span>><\/span><\/span> proxyClass =<\/span> ref !=<\/span> null<\/span> ?<\/span> ref.<\/span>get<\/span>(<\/span>)<\/span> :<\/span> null<\/span>;<\/span><\/p>\n

                                                    \/\/ \u7f13\u5b58\u547d\u4e2d\u4e14\u672a\u88ab\u56de\u6536<\/span>
                                                    \n if<\/span> (<\/span>proxyClass !=<\/span> null<\/span>)<\/span> {<\/span>
                                                    \n return<\/span> proxyClass;<\/span>
                                                    \n }<\/span><\/p>\n

                                                    \/\/ \u751f\u6210\u65b0\u4ee3\u7406\u7c7b<\/span>
                                                    \n proxyClass =<\/span> BYTE_BUDDY
                                                    \n .<\/span>subclass<\/span>(<\/span>targetClass)<\/span>
                                                    \n .<\/span>name<\/span>(<\/span>targetClass.<\/span>getName<\/span>(<\/span>)<\/span> +<\/span> "$$WeakProxy"<\/span>)<\/span>
                                                    \n .<\/span>make<\/span>(<\/span>)<\/span>
                                                    \n .<\/span>load<\/span>(<\/span>targetClass.<\/span>getClassLoader<\/span>(<\/span>)<\/span>,<\/span>
                                                    \n ClassLoadingStrategy.<\/span>Default<\/span>.<\/span>WRAPPER)<\/span>
                                                    \n .<\/span>getLoaded<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                    \/\/ \u5b58\u5165\u5f31\u5f15\u7528<\/span>
                                                    \n WEAK_CACHE.<\/span>put<\/span>(<\/span>targetClass,<\/span> new<\/span> WeakReference<\/span><<\/span>><\/span><\/span>(<\/span>proxyClass)<\/span>)<\/span>;<\/span><\/p>\n

                                                    \/\/ \u6e05\u7406\u5df2\u56de\u6536\u7684\u6761\u76ee<\/span>
                                                    \n if<\/span> (<\/span>WEAK_CACHE.<\/span>size<\/span>(<\/span>)<\/span> ><\/span> 1000<\/span>)<\/span> {<\/span>
                                                    \n WEAK_CACHE.<\/span>entrySet<\/span>(<\/span>)<\/span>.<\/span>removeIf<\/span>(<\/span>entry -><\/span>
                                                    \n entry.<\/span>getValue<\/span>(<\/span>)<\/span>.<\/span>get<\/span>(<\/span>)<\/span> ==<\/span> null<\/span>)<\/span>;<\/span>
                                                    \n }<\/span><\/p>\n

                                                    return<\/span> proxyClass;<\/span>
                                                    \n }<\/span>
                                                    \n }<\/span><\/p>\n

                                                    \/**
                                                    \n * \u4e3b\u52a8\u89e6\u53d1\u6e05\u7406
                                                    \n *\/<\/span>
                                                    \n public<\/span> static<\/span> void<\/span> cleanCache<\/span>(<\/span>)<\/span> {<\/span>
                                                    \n synchronized<\/span> (<\/span>WEAK_CACHE)<\/span> {<\/span>
                                                    \n WEAK_CACHE.<\/span>entrySet<\/span>(<\/span>)<\/span>.<\/span>removeIf<\/span>(<\/span>entry -><\/span>
                                                    \n entry.<\/span>getValue<\/span>(<\/span>)<\/span>.<\/span>get<\/span>(<\/span>)<\/span> ==<\/span> null<\/span>)<\/span>;<\/span>
                                                    \n }<\/span>
                                                    \n }<\/span>
                                                    \n}<\/span><\/p>\n

                                                    \u56de\u6536\u673a\u5236：<\/p>\n

                                                    1. \u76ee\u6807\u7c7b\u4e0d\u518d\u4f7f\u7528 \u2192 \u88abGC\u56de\u6536
                                                    \n2. WeakHashMap\u81ea\u52a8\u79fb\u9664\u5bf9\u5e94entry
                                                    \n3. \u4ee3\u7406\u7c7b\u5931\u53bb\u5f3a\u5f15\u7528 \u2192 \u5143\u7a7a\u95f4\u53ef\u56de\u6536<\/p>\n

                                                    \n
                                                    \u2705 \u65b9\u6848\u4e09：\u81ea\u5b9a\u4e49\u7c7b\u52a0\u8f7d\u5668\u9694\u79bb<\/h5>\n

                                                    \u9002\u7528\u4e8e：\u591a\u79df\u6237\u73af\u5883\u3001\u70ed\u90e8\u7f72\u573a\u666f<\/p>\n

                                                    package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                                    import<\/span> net.<\/span>bytebuddy.<\/span><\/span>ByteBuddy<\/span>;<\/span>
                                                    \nimport<\/span> net.<\/span>bytebuddy.<\/span>dynamic.<\/span>loading.<\/span><\/span>ClassLoadingStrategy<\/span>;<\/span>
                                                    \nimport<\/span> java.<\/span>io.<\/span><\/span>Closeable<\/span>;<\/span>
                                                    \nimport<\/span> java.<\/span>io.<\/span><\/span>IOException<\/span>;<\/span>
                                                    \nimport<\/span> java.<\/span>util.<\/span><\/span>Map<\/span>;<\/span>
                                                    \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>ConcurrentHashMap<\/span>;<\/span>
                                                    \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span>atomic.<\/span><\/span>AtomicInteger<\/span>;<\/span><\/p>\n

                                                    \/**
                                                    \n * \u89e3\u51b3\u65b9\u68483：\u7c7b\u52a0\u8f7d\u5668\u9694\u79bb
                                                    \n * \u539f\u7406：\u6bcf\u4e2a\u4e1a\u52a1\u5355\u5143\u72ec\u7acbClassLoader，\u7528\u5b8c\u540e\u6574\u4f53\u5378\u8f7d
                                                    \n *\/<\/span>
                                                    \npublic<\/span> class<\/span> MetaspaceOOM_Fix3_IsolatedClassLoader<\/span> {<\/span><\/p>\n

                                                    private<\/span> static<\/span> final<\/span> Map<\/span><<\/span>String<\/span>,<\/span> IsolatedClassLoader<\/span>><\/span><\/span> LOADER_POOL =<\/span>
                                                    \n new<\/span> ConcurrentHashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                                    \n private<\/span> static<\/span> final<\/span> AtomicInteger<\/span> COUNTER =<\/span> new<\/span> AtomicInteger<\/span>(<\/span>0<\/span>)<\/span>;<\/span><\/p>\n

                                                    \/**
                                                    \n * \u53ef\u5378\u8f7d\u7684\u7c7b\u52a0\u8f7d\u5668
                                                    \n *\/<\/span>
                                                    \n public<\/span> static<\/span> class<\/span> IsolatedClassLoader<\/span> extends<\/span> ClassLoader<\/span>
                                                    \n implements<\/span> Closeable<\/span> {<\/span><\/p>\n

                                                    private<\/span> final<\/span> String<\/span> id;<\/span>
                                                    \n private<\/span> final<\/span> ByteBuddy<\/span> byteBuddy;<\/span>
                                                    \n private<\/span> volatile<\/span> boolean<\/span> closed =<\/span> false<\/span>;<\/span><\/p>\n

                                                    public<\/span> IsolatedClassLoader<\/span>(<\/span>String<\/span> id)<\/span> {<\/span>
                                                    \n super<\/span>(<\/span>Thread<\/span>.<\/span>currentThread<\/span>(<\/span>)<\/span>.<\/span>getContextClassLoader<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                    \n this<\/span>.<\/span>id =<\/span> id;<\/span>
                                                    \n this<\/span>.<\/span>byteBuddy =<\/span> new<\/span> ByteBuddy<\/span>(<\/span>)<\/span>;<\/span>
                                                    \n }<\/span><\/p>\n

                                                    \/**
                                                    \n * \u5728\u5f53\u524d\u7c7b\u52a0\u8f7d\u5668\u4e2d\u751f\u6210\u4ee3\u7406\u7c7b
                                                    \n *\/<\/span>
                                                    \n public<\/span> Class<\/span><<\/span>?<\/span>><\/span><\/span> generateProxy<\/span>(<\/span>Class<\/span><<\/span>?<\/span>><\/span><\/span> targetClass)<\/span> {<\/span>
                                                    \n if<\/span> (<\/span>closed)<\/span> {<\/span>
                                                    \n throw<\/span> new<\/span> IllegalStateException<\/span>(<\/span>"ClassLoader\u5df2\u5173\u95ed"<\/span>)<\/span>;<\/span>
                                                    \n }<\/span><\/p>\n

                                                    return<\/span> byteBuddy
                                                    \n .<\/span>subclass<\/span>(<\/span>targetClass)<\/span>
                                                    \n .<\/span>name<\/span>(<\/span>targetClass.<\/span>getName<\/span>(<\/span>)<\/span> +<\/span> "$Proxy$"<\/span> +<\/span> id +<\/span> "$"<\/span> +<\/span> COUNTER.<\/span>incrementAndGet<\/span>(<\/span>)<\/span>)<\/span>
                                                    \n .<\/span>make<\/span>(<\/span>)<\/span>
                                                    \n .<\/span>load<\/span>(<\/span>this<\/span>,<\/span> ClassLoadingStrategy.<\/span>Default<\/span>.<\/span>WRAPPER)<\/span>
                                                    \n .<\/span>getLoaded<\/span>(<\/span>)<\/span>;<\/span>
                                                    \n }<\/span><\/p>\n

                                                    @Override<\/span>
                                                    \n public<\/span> void<\/span> close<\/span>(<\/span>)<\/span> throws<\/span> IOException<\/span> {<\/span>
                                                    \n this<\/span>.<\/span>closed =<\/span> true<\/span>;<\/span>
                                                    \n LOADER_POOL.<\/span>remove<\/span>(<\/span>id)<\/span>;<\/span><\/p>\n

                                                    \/\/ \u6e05\u7a7a\u7f13\u5b58，\u5141\u8bb8GC\u56de\u6536<\/span>
                                                    \n byteBuddy.<\/span>close<\/span>(<\/span>)<\/span>;<\/span>
                                                    \n }<\/span><\/p>\n

                                                    @Override<\/span>
                                                    \n protected<\/span> void<\/span> finalize<\/span>(<\/span>)<\/span> {<\/span>
                                                    \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[GC] \u7c7b\u52a0\u8f7d\u5668\u88ab\u56de\u6536: %s%n"<\/span>,<\/span> id)<\/span>;<\/span>
                                                    \n }<\/span>
                                                    \n }<\/span><\/p>\n

                                                    \/**
                                                    \n * \u521b\u5efa\u9694\u79bb\u73af\u5883
                                                    \n *\/<\/span>
                                                    \n public<\/span> static<\/span> IsolatedClassLoader<\/span> createIsolatedEnv<\/span>(<\/span>String<\/span> bizId)<\/span> {<\/span>
                                                    \n return<\/span> LOADER_POOL.<\/span>computeIfAbsent<\/span>(<\/span>bizId,<\/span>
                                                    \n id -><\/span> new<\/span> IsolatedClassLoader<\/span>(<\/span>id)<\/span>)<\/span>;<\/span>
                                                    \n }<\/span><\/p>\n

                                                    \/**
                                                    \n * \u6f14\u793a：\u6bcf\u4e2aHTTP\u8bf7\u6c42\u72ec\u7acbClassLoader
                                                    \n *\/<\/span>
                                                    \n public<\/span> static<\/span> void<\/span> handleRequest<\/span>(<\/span>String<\/span> requestId)<\/span> {<\/span>
                                                    \n IsolatedClassLoader<\/span> loader =<\/span> createIsolatedEnv<\/span>(<\/span>requestId)<\/span>;<\/span><\/p>\n

                                                    try<\/span> {<\/span>
                                                    \n \/\/ \u5728\u9694\u79bb\u73af\u5883\u4e2d\u751f\u6210\u4ee3\u7406\u7c7b<\/span>
                                                    \n Class<\/span><<\/span>?<\/span>><\/span><\/span> proxyClass =<\/span> loader.<\/span>generateProxy<\/span>(<\/span>TargetClass<\/span>.<\/span>class<\/span>)<\/span>;<\/span><\/p>\n

                                                    \/\/ \u6267\u884c\u4e1a\u52a1\u903b\u8f91<\/span>
                                                    \n Object<\/span> instance =<\/span> proxyClass.<\/span>getDeclaredConstructor<\/span>(<\/span>)<\/span>.<\/span>newInstance<\/span>(<\/span>)<\/span>;<\/span>
                                                    \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u8bf7\u6c42%s\u4f7f\u7528\u4ee3\u7406: %s%n"<\/span>,<\/span>
                                                    \n requestId,<\/span> proxyClass.<\/span>getSimpleName<\/span>(<\/span>)<\/span>)<\/span>;<\/span><\/p>\n

                                                    }<\/span> catch<\/span> (<\/span>Exception<\/span> e)<\/span> {<\/span>
                                                    \n e.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>
                                                    \n }<\/span> finally<\/span> {<\/span>
                                                    \n try<\/span> {<\/span>
                                                    \n loader.<\/span>close<\/span>(<\/span>)<\/span>;<\/span> \/\/ \u4e3b\u52a8\u91ca\u653e<\/span>
                                                    \n }<\/span> catch<\/span> (<\/span>IOException<\/span> e)<\/span> {<\/span>
                                                    \n e.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>
                                                    \n }<\/span>
                                                    \n }<\/span>
                                                    \n }<\/span><\/p>\n

                                                    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> Exception<\/span> {<\/span>
                                                    \n \/\/ \u6a21\u62df1000\u4e2a\u5e76\u53d1\u8bf7\u6c42<\/span>
                                                    \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 1000<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>
                                                    \n handleRequest<\/span>(<\/span>"req-"<\/span> +<\/span> i)<\/span>;<\/span><\/p>\n

                                                    \/\/ \u4e3b\u52a8GC，\u89c2\u5bdf\u7c7b\u52a0\u8f7d\u5668\u56de\u6536<\/span>
                                                    \n if<\/span> (<\/span>i %<\/span> 100<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                    \n System<\/span>.<\/span>gc<\/span>(<\/span>)<\/span>;<\/span>
                                                    \n Thread<\/span>.<\/span>sleep<\/span>(<\/span>100<\/span>)<\/span>;<\/span>
                                                    \n }<\/span>
                                                    \n }<\/span>
                                                    \n }<\/span><\/p>\n

                                                    public<\/span> static<\/span> class<\/span> TargetClass<\/span> {<\/span>}<\/span>
                                                    \n}<\/span><\/p>\n

                                                    \u4f18\u52bf：<\/p>\n

                                                      \n
                                                    • \u2705 \u5f7b\u5e95\u5378\u8f7d – \u6574\u4e2aClassLoader\u53ef\u56de\u6536<\/li>\n
                                                    • \u2705 \u5b8c\u5168\u9694\u79bb – \u79df\u6237\u95f4\u4e92\u4e0d\u5f71\u54cd<\/li>\n
                                                    • \u2705 \u8d44\u6e90\u53ef\u63a7 – \u4e3b\u52a8\u5173\u95ed\u673a\u5236<\/li>\n<\/ul>\n
                                                      \n
                                                      \u2705 \u65b9\u6848\u56db：\u5143\u7a7a\u95f4\u76d1\u63a7\u4e0e\u544a\u8b66<\/h5>\n

                                                      \u9002\u7528\u4e8e：\u751f\u4ea7\u73af\u5883\u9884\u9632，\u63d0\u524d\u53d1\u73b0\u6cc4\u6f0f<\/p>\n

                                                      package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                                      import<\/span> javax.<\/span>management.<\/span><\/span>*<\/span>;<\/span>
                                                      \nimport<\/span> java.<\/span>lang.<\/span>management.<\/span><\/span>*<\/span>;<\/span>
                                                      \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>Executors<\/span>;<\/span>
                                                      \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>TimeUnit<\/span>;<\/span><\/p>\n

                                                      \/**
                                                      \n * \u89e3\u51b3\u65b9\u68484：\u5143\u7a7a\u95f4\u76d1\u63a7
                                                      \n * \u539f\u7406：\u5b9e\u65f6\u76d1\u63a7\u5143\u7a7a\u95f4\u4f7f\u7528\u7387，\u63d0\u524d\u9884\u8b66
                                                      \n *\/<\/span>
                                                      \npublic<\/span> class<\/span> MetaspaceOOM_Fix4_Monitor<\/span> {<\/span><\/p>\n

                                                      private<\/span> static<\/span> final<\/span> double<\/span> WARNING_THRESHOLD =<\/span> 0.8<\/span>;<\/span> \/\/ 80%\u544a\u8b66\u9608\u503c<\/span>
                                                      \n private<\/span> static<\/span> final<\/span> double<\/span> CRITICAL_THRESHOLD =<\/span> 0.95<\/span>;<\/span> \/\/ 95%\u4e25\u91cd\u544a\u8b66<\/span><\/p>\n

                                                      public<\/span> static<\/span> void<\/span> startMonitor<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n Executors<\/span>.<\/span>newSingleThreadScheduledExecutor<\/span>(<\/span>)<\/span>
                                                      \n .<\/span>scheduleAtFixedRate<\/span>(<\/span>(<\/span>)<\/span> -><\/span> {<\/span>
                                                      \n try<\/span> {<\/span>
                                                      \n for<\/span> (<\/span>MemoryPoolMXBean<\/span> pool :<\/span> ManagementFactory<\/span>.<\/span>getMemoryPoolMXBeans<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                                      \n if<\/span> (<\/span>pool.<\/span>getName<\/span>(<\/span>)<\/span>.<\/span>contains<\/span>(<\/span>"Metaspace"<\/span>)<\/span>)<\/span> {<\/span>
                                                      \n MemoryUsage<\/span> usage =<\/span> pool.<\/span>getUsage<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n long<\/span> used =<\/span> usage.<\/span>getUsed<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n long<\/span> max =<\/span> usage.<\/span>getMax<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                      if<\/span> (<\/span>max <=<\/span> 0<\/span>)<\/span> continue<\/span>;<\/span><\/p>\n

                                                      double<\/span> ratio =<\/span> (<\/span>double<\/span>)<\/span> used \/<\/span> max;<\/span>
                                                      \n String<\/span> level =<\/span> "INFO"<\/span>;<\/span><\/p>\n

                                                      if<\/span> (<\/span>ratio >=<\/span> CRITICAL_THRESHOLD)<\/span> {<\/span>
                                                      \n level =<\/span> "CRITICAL"<\/span>;<\/span>
                                                      \n \/\/ \u89e6\u53d1\u5806\u8f6c\u50a8<\/span>
                                                      \n triggerHeapDump<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n }<\/span> else<\/span> if<\/span> (<\/span>ratio >=<\/span> WARNING_THRESHOLD)<\/span> {<\/span>
                                                      \n level =<\/span> "WARNING"<\/span>;<\/span>
                                                      \n \/\/ \u53d1\u9001\u544a\u8b66<\/span>
                                                      \n sendAlert<\/span>(<\/span>level,<\/span> used,<\/span> max)<\/span>;<\/span>
                                                      \n }<\/span><\/p>\n

                                                      System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[%s] Metaspace: %dMB\/%dMB (%.1f%%)%n"<\/span>,<\/span>
                                                      \n level,<\/span>
                                                      \n used \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>,<\/span>
                                                      \n max \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>,<\/span>
                                                      \n ratio *<\/span> 100<\/span>)<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ \u76d1\u63a7\u7c7b\u52a0\u8f7d\u5668\u6570\u91cf<\/span>
                                                      \n int<\/span> classLoaderCount =<\/span> ManagementFactory<\/span>.<\/span>getClassLoadingMXBean<\/span>(<\/span>)<\/span>
                                                      \n .<\/span>getLoadedClassCount<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n if<\/span> (<\/span>classLoaderCount ><\/span> 50000<\/span>)<\/span> {<\/span>
                                                      \n System<\/span>.<\/span>err.<\/span>printf<\/span>(<\/span>"[ALERT] \u7c7b\u6570\u91cf\u5f02\u5e38: %d%n"<\/span>,<\/span> classLoaderCount)<\/span>;<\/span>
                                                      \n }<\/span><\/p>\n

                                                      }<\/span> catch<\/span> (<\/span>Exception<\/span> e)<\/span> {<\/span>
                                                      \n e.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span>,<\/span> 0<\/span>,<\/span> 10<\/span>,<\/span> TimeUnit<\/span>.<\/span>SECONDS)<\/span>;<\/span>
                                                      \n }<\/span><\/p>\n

                                                      private<\/span> static<\/span> void<\/span> triggerHeapDump<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n \/\/ \u8c03\u7528HeapDump（\u901a\u8fc7HotSpotDiagnosticMXBean）<\/span>
                                                      \n try<\/span> {<\/span>
                                                      \n Class<\/span><<\/span>?<\/span>><\/span><\/span> clazz =<\/span> Class<\/span>.<\/span>forName<\/span>(<\/span>"com.sun.management.HotSpotDiagnosticMXBean"<\/span>)<\/span>;<\/span>
                                                      \n MBeanServer<\/span> server =<\/span> ManagementFactory<\/span>.<\/span>getPlatformMBeanServer<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n ObjectInstance<\/span> instance =<\/span> server.<\/span>queryMBeans<\/span>(<\/span>
                                                      \n new<\/span> ObjectName<\/span>(<\/span>"com.sun.management:type=HotSpotDiagnostic"<\/span>)<\/span>,<\/span> null<\/span>)<\/span>
                                                      \n .<\/span>iterator<\/span>(<\/span>)<\/span>.<\/span>next<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                      Object<\/span> mxbean =<\/span> ManagementFactory<\/span>.<\/span>newPlatformMXBeanProxy<\/span>(<\/span>
                                                      \n server,<\/span>
                                                      \n instance.<\/span>getObjectName<\/span>(<\/span>)<\/span>.<\/span>getCanonicalName<\/span>(<\/span>)<\/span>,<\/span>
                                                      \n clazz)<\/span>;<\/span><\/p>\n

                                                      java.<\/span>lang.<\/span>reflect.<\/span><\/span>Method<\/span> dumpMethod =<\/span> clazz.<\/span>getMethod<\/span>(<\/span>
                                                      \n "dumpHeap"<\/span>,<\/span> String<\/span>.<\/span>class<\/span>,<\/span> boolean<\/span>.<\/span>class<\/span>)<\/span>;<\/span><\/p>\n

                                                      String<\/span> fileName =<\/span> "heap_"<\/span> +<\/span> System<\/span>.<\/span>currentTimeMillis<\/span>(<\/span>)<\/span> +<\/span> ".hprof"<\/span>;<\/span>
                                                      \n dumpMethod.<\/span>invoke<\/span>(<\/span>mxbean,<\/span> fileName,<\/span> true<\/span>)<\/span>;<\/span><\/p>\n

                                                      System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[DUMP] \u5806\u8f6c\u50a8\u5df2\u751f\u6210: %s%n"<\/span>,<\/span> fileName)<\/span>;<\/span>
                                                      \n }<\/span> catch<\/span> (<\/span>Exception<\/span> e)<\/span> {<\/span>
                                                      \n System<\/span>.<\/span>err.<\/span>println<\/span>(<\/span>"[ERROR] \u5806\u8f6c\u50a8\u5931\u8d25: "<\/span> +<\/span> e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span><\/p>\n

                                                      private<\/span> static<\/span> void<\/span> sendAlert<\/span>(<\/span>String<\/span> level,<\/span> long<\/span> used,<\/span> long<\/span> max)<\/span> {<\/span>
                                                      \n \/\/ \u96c6\u6210\u9489\u9489\/\u5fae\u4fe1\/\u90ae\u4ef6\u544a\u8b66<\/span>
                                                      \n System<\/span>.<\/span>err.<\/span>printf<\/span>(<\/span>"[%s] \u5143\u7a7a\u95f4\u5373\u5c06\u8017\u5c3d! used=%dMB, max=%dMB%n"<\/span>,<\/span>
                                                      \n level,<\/span> used \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>,<\/span> max \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span>
                                                      \n }<\/span><\/p>\n

                                                      public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                      \n startMonitor<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n \/\/ \u4fdd\u6301\u8fd0\u884c<\/span>
                                                      \n try<\/span> {<\/span> Thread<\/span>.<\/span>sleep<\/span>(<\/span>Long<\/span>.<\/span>MAX_VALUE)<\/span>;<\/span> }<\/span> catch<\/span> (<\/span>InterruptedException<\/span> e)<\/span> {<\/span>}<\/span>
                                                      \n }<\/span>
                                                      \n}<\/span><\/p>\n

                                                      \n
                                                      \u2705 \u65b9\u6848\u4e94：JDK\u52a8\u6001\u4ee3\u7406\u66ff\u4ee3\u65b9\u6848<\/h5>\n

                                                      \u9002\u7528\u4e8e：\u57fa\u4e8e\u63a5\u53e3\u7684\u4ee3\u7406\u573a\u666f<\/p>\n

                                                      package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                                      import<\/span> java.<\/span>lang.<\/span>reflect.<\/span><\/span>InvocationHandler<\/span>;<\/span>
                                                      \nimport<\/span> java.<\/span>lang.<\/span>reflect.<\/span><\/span>Method<\/span>;<\/span>
                                                      \nimport<\/span> java.<\/span>lang.<\/span>reflect.<\/span><\/span>Proxy<\/span>;<\/span>
                                                      \nimport<\/span> java.<\/span>util.<\/span><\/span>Map<\/span>;<\/span>
                                                      \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>ConcurrentHashMap<\/span>;<\/span><\/p>\n

                                                      \/**
                                                      \n * \u89e3\u51b3\u65b9\u68485：JDK\u52a8\u6001\u4ee3\u7406
                                                      \n * \u539f\u7406：\u8fd0\u884c\u65f6\u751f\u6210\u5b57\u8282\u7801，\u800c\u975e\u7f16\u8bd1\u671f\u751f\u6210\u65b0\u7c7b
                                                      \n *\/<\/span>
                                                      \npublic<\/span> class<\/span> MetaspaceOOM_Fix5_JdkProxy<\/span> {<\/span><\/p>\n

                                                      \/\/ \u4e1a\u52a1\u63a5\u53e3<\/span>
                                                      \n public<\/span> interface<\/span> UserService<\/span> {<\/span>
                                                      \n void<\/span> sayHello<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ \u76ee\u6807\u7c7b<\/span>
                                                      \n public<\/span> static<\/span> class<\/span> UserServiceImpl<\/span> implements<\/span> UserService<\/span> {<\/span>
                                                      \n @Override<\/span>
                                                      \n public<\/span> void<\/span> sayHello<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"Hello from UserService"<\/span>)<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ JDK\u52a8\u6001\u4ee3\u7406\u5de5\u5382<\/span>
                                                      \n public<\/span> static<\/span> class<\/span> JdkProxyFactory<\/span> {<\/span>
                                                      \n private<\/span> static<\/span> final<\/span> Map<\/span><<\/span>Class<\/span><<\/span>?<\/span>><\/span>,<\/span> Class<\/span><<\/span>?<\/span>><\/span>><\/span><\/span> PROXY_CACHE =<\/span> new<\/span> ConcurrentHashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                      @SuppressWarnings<\/span>(<\/span>"unchecked"<\/span>)<\/span>
                                                      \n public<\/span> static<\/span> <<\/span>T<\/span>><\/span><\/span> T<\/span> createProxy<\/span>(<\/span>T<\/span> target)<\/span> {<\/span>
                                                      \n Class<\/span><<\/span>?<\/span>><\/span><\/span> targetClass =<\/span> target.<\/span>getClass<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n Class<\/span><<\/span>?<\/span>><\/span><\/span>[<\/span>]<\/span> interfaces =<\/span> targetClass.<\/span>getInterfaces<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                      if<\/span> (<\/span>interfaces.<\/span>length ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                      \n throw<\/span> new<\/span> IllegalArgumentException<\/span>(<\/span>"\u76ee\u6807\u7c7b\u5fc5\u987b\u5b9e\u73b0\u63a5\u53e3"<\/span>)<\/span>;<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ JDK\u52a8\u6001\u4ee3\u7406\u53ea\u751f\u6210\u4e00\u4e2aProxy0\u7c7b<\/span>
                                                      \n return<\/span> (<\/span>T<\/span>)<\/span> Proxy<\/span>.<\/span>newProxyInstance<\/span>(<\/span>
                                                      \n targetClass.<\/span>getClassLoader<\/span>(<\/span>)<\/span>,<\/span>
                                                      \n interfaces,<\/span>
                                                      \n new<\/span> InvocationHandler<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n @Override<\/span>
                                                      \n public<\/span> Object<\/span> invoke<\/span>(<\/span>Object<\/span> proxy,<\/span> Method<\/span> method,<\/span> Object<\/span>[<\/span>]<\/span> args)<\/span>
                                                      \n throws<\/span> Throwable<\/span> {<\/span>
                                                      \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"[JDK Proxy] \u524d\u7f6e\u589e\u5f3a"<\/span>)<\/span>;<\/span>
                                                      \n Object<\/span> result =<\/span> method.<\/span>invoke<\/span>(<\/span>target,<\/span> args)<\/span>;<\/span>
                                                      \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"[JDK Proxy] \u540e\u7f6e\u589e\u5f3a"<\/span>)<\/span>;<\/span>
                                                      \n return<\/span> result;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span>
                                                      \n )<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span><\/p>\n

                                                      public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                      \n UserService<\/span> target =<\/span> new<\/span> UserServiceImpl<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                      \/\/ \u751f\u6210100\u4e07\u6b21\u4ee3\u7406，\u5143\u7a7a\u95f4\u65e0\u589e\u957f<\/span>
                                                      \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 1000000<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>
                                                      \n UserService<\/span> proxy =<\/span> JdkProxyFactory<\/span>.<\/span>createProxy<\/span>(<\/span>target)<\/span>;<\/span>
                                                      \n if<\/span> (<\/span>i %<\/span> 100000<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                      \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u7b2c%d\u6b21\u751f\u6210\u4ee3\u7406: %s%n"<\/span>,<\/span>
                                                      \n i,<\/span> proxy.<\/span>getClass<\/span>(<\/span>)<\/span>.<\/span>getName<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                      \n proxy.<\/span>sayHello<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ \u9a8c\u8bc1：Proxy0\u7c7b\u53ea\u751f\u6210\u4e00\u6b21<\/span>
                                                      \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u6700\u7ec8\u4ee3\u7406\u7c7b: "<\/span> +<\/span>
                                                      \n Proxy<\/span>.<\/span>getProxyClass<\/span>(<\/span>UserService<\/span>.<\/span>class<\/span>.<\/span>getClassLoader<\/span>(<\/span>)<\/span>,<\/span>
                                                      \n UserService<\/span>.<\/span>class<\/span>)<\/span>.<\/span>getName<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n}<\/span><\/p>\n

                                                      \u5bf9\u6bd4JDK Proxy vs ByteBuddy\/CGLIB：<\/p>\n\n\u7279\u6027JDK\u52a8\u6001\u4ee3\u7406ByteBuddy\/CGLIB<\/tr>\n\n\n\n\n\n\n
                                                      \u4f9d\u8d56\u63a5\u53e3<\/td>\n\u5fc5\u987b<\/td>\n\u65e0\u9700\u63a5\u53e3<\/td>\n<\/tr>\n
                                                      \u751f\u6210\u7c7b\u6570<\/td>\n1\u4e2a（\u590d\u7528）<\/td>\nN\u4e2a（\u6bcf\u4e2a\u76ee\u6807\u7c7b1\u4e2a）<\/td>\n<\/tr>\n
                                                      \u6027\u80fd<\/td>\n\u53cd\u5c04\u8c03\u7528<\/td>\n\u76f4\u63a5\u8c03\u7528（\u5feb）<\/td>\n<\/tr>\n
                                                      \u5143\u7a7a\u95f4\u5360\u7528<\/td>\n\u6781\u4f4e<\/td>\n\u8f83\u9ad8<\/td>\n<\/tr>\n
                                                      \u9002\u7528\u573a\u666f<\/td>\n\u6709\u63a5\u53e3\u7684\u4e1a\u52a1<\/td>\n\u65e0\u63a5\u53e3\/\u6846\u67b6\u96c6\u6210<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
                                                      \n

                                                      4.5 \u65b9\u6848\u5bf9\u6bd4\u4e0e\u9009\u578b\u5efa\u8bae<\/h4>\n\n\u5bf9\u6bd4\u7ef4\u5ea6\u65b9\u68481 \u7f13\u5b58\u65b9\u68482 \u5f31\u5f15\u7528\u65b9\u68483 \u9694\u79bbCL\u65b9\u68484 \u76d1\u63a7\u65b9\u68485 JDK\u4ee3\u7406<\/tr>\n\n\n\n\n\n\n
                                                      \u5185\u5b58\u5b89\u5168\u6027<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n<\/tr>\n
                                                      \u5b9e\u73b0\u590d\u6742\u5ea6<\/td>\n\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50<\/td>\n<\/tr>\n
                                                      \u6027\u80fd<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n<\/tr>\n
                                                      \u9002\u7528\u5e7f\u5ea6<\/td>\n\u76ee\u6807\u7c7b\u56fa\u5b9a<\/td>\n\u76ee\u6807\u7c7b\u52a8\u6001<\/td>\n\u591a\u79df\u6237<\/td>\n\u6240\u6709\u573a\u666f<\/td>\n\u6709\u63a5\u53e3<\/td>\n<\/tr>\n
                                                      \u63a8\u8350\u6307\u6570<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                                                      \u9009\u578b\u51b3\u7b56\u6811：<\/p>\n

                                                      \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                      \n \u2502 \u5143\u7a7a\u95f4\u6ea2\u51fa \u2502
                                                      \n \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                                      \n \u2193
                                                      \n \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                      \n \u2502 \u2502
                                                      \n \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                      \n \u2502 \u76ee\u6807\u7c7b\u662f\u5426 \u2502 \u662f \u2502 \u76ee\u6807\u7c7b\u662f\u5426 \u2502
                                                      \n \u2502 \u6570\u91cf\u56fa\u5b9a？ \u2502 \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2192 \u2502 \u5b9e\u73b0\u63a5\u53e3？ \u2502
                                                      \n \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                                      \n \u2502 \u5426 \u2502 \u5426
                                                      \n \u2193 \u2193
                                                      \n \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                      \n \u2502 \u65b9\u68481: \u7f13\u5b58 \u2502 \u2502 \u65b9\u68485: JDK \u2502
                                                      \n \u2502 \u590d\u7528\u4ee3\u7406\u7c7b \u2502 \u2502 \u52a8\u6001\u4ee3\u7406 \u2502
                                                      \n \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                                      \n \u2193 \u2193
                                                      \n \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                      \n \u2502 \u65b9\u68483: \u9694\u79bb \u2502 \u2502 \u65b9\u68482: \u5f31\u5f15\u7528 \u2502
                                                      \n \u2502 \u591a\u79df\u6237\u573a\u666f \u2502 \u2502 \u81ea\u52a8\u56de\u6536 \u2502
                                                      \n \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/p>\n

                                                      \n

                                                      4.6 \u9884\u9632\u63aa\u65bd\u4e0e\u7f16\u7801\u89c4\u8303<\/h4>\n

                                                      \/**
                                                      \n * \u52a8\u6001\u4ee3\u7406\u4f7f\u7528\u89c4\u8303
                                                      \n *\/<\/span>
                                                      \npublic<\/span> class<\/span> MetaspaceGuard<\/span> {<\/span><\/p>\n

                                                      \/\/ \u274c \u9519\u8bef\u793a\u4f8b1：\u6bcf\u6b21\u751f\u6210\u65b0\u7c7b\u540d<\/span>
                                                      \n public<\/span> void<\/span> badProxy1<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n new<\/span> ByteBuddy<\/span>(<\/span>)<\/span>
                                                      \n .<\/span>subclass<\/span>(<\/span>Object<\/span>.<\/span>class<\/span>)<\/span>
                                                      \n .<\/span>name<\/span>(<\/span>"Proxy_"<\/span> +<\/span> System<\/span>.<\/span>currentTimeMillis<\/span>(<\/span>)<\/span>)<\/span> \/\/ \u6bcf\u6b21\u4e0d\u540c<\/span>
                                                      \n .<\/span>make<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ \u2705 \u6b63\u786e\u793a\u4f8b1：\u56fa\u5b9a\u7c7b\u540d<\/span>
                                                      \n public<\/span> void<\/span> goodProxy1<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n new<\/span> ByteBuddy<\/span>(<\/span>)<\/span>
                                                      \n .<\/span>subclass<\/span>(<\/span>Object<\/span>.<\/span>class<\/span>)<\/span>
                                                      \n .<\/span>name<\/span>(<\/span>"com.example.Proxy"<\/span>)<\/span> \/\/ \u56fa\u5b9a\u540d\u79f0<\/span>
                                                      \n .<\/span>make<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ \u274c \u9519\u8bef\u793a\u4f8b2：\u4e0d\u7f13\u5b58\u4ee3\u7406\u7c7b<\/span>
                                                      \n public<\/span> void<\/span> badProxy2<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n \/\/ \u6bcf\u6b21\u90fd\u751f\u6210\u65b0\u7c7b<\/span>
                                                      \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 1000<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>
                                                      \n generateProxy<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ \u2705 \u6b63\u786e\u793a\u4f8b2：\u7f13\u5b58\u4ee3\u7406\u7c7b<\/span>
                                                      \n private<\/span> static<\/span> Class<\/span><<\/span>?<\/span>><\/span><\/span> cachedProxy;<\/span>
                                                      \n public<\/span> void<\/span> goodProxy2<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n if<\/span> (<\/span>cachedProxy ==<\/span> null<\/span>)<\/span> {<\/span>
                                                      \n cachedProxy =<\/span> generateProxy<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n }<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ \u274c \u9519\u8bef\u793a\u4f8b3：\u7c7b\u52a0\u8f7d\u5668\u6cc4\u6f0f<\/span>
                                                      \n public<\/span> void<\/span> badProxy3<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n ClassLoader<\/span> cl =<\/span> new<\/span> CustomClassLoader<\/span>(<\/span>)<\/span>;<\/span>
                                                      \n \/\/ \u4f7f\u7528\u540e\u672a\u91ca\u653e\u5f15\u7528<\/span>
                                                      \n }<\/span><\/p>\n

                                                      \/\/ \u2705 \u6b63\u786e\u793a\u4f8b3：try-with-resources<\/span>
                                                      \n public<\/span> void<\/span> goodProxy3<\/span>(<\/span>)<\/span> {<\/span>
                                                      \n try<\/span> (<\/span>CustomClassLoader<\/span> cl =<\/span> new<\/span> CustomClassLoader<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                                      \n \/\/ \u4f7f\u7528\u7c7b\u52a0\u8f7d\u5668<\/span>
                                                      \n }<\/span> \/\/ \u81ea\u52a8close<\/span>
                                                      \n }<\/span>
                                                      \n}<\/span><\/p>\n

                                                      \u751f\u4ea7\u73af\u5883JVM\u53c2\u6570\u5efa\u8bae：<\/p>\n

                                                      # \u5143\u7a7a\u95f4\u751f\u4ea7\u914d\u7f6e<\/span>
                                                      \n-XX:MetaspaceSize=<\/span>256m # \u521d\u59cb\u5143\u7a7a\u95f4（\u907f\u514d\u9891\u7e41\u6269\u5bb9）<\/span>
                                                      \n-XX:MaxMetaspaceSize=<\/span>512m # \u6700\u5927\u5143\u7a7a\u95f4（\u9632OOM\u5f71\u54cd\u4e1a\u52a1）<\/span>
                                                      \n-XX:CompressedClassSpaceSize=<\/span>128m # \u538b\u7f29\u7c7b\u7a7a\u95f4<\/span>
                                                      \n-XX:+TraceClassLoading # \u76d1\u63a7\u7c7b\u52a0\u8f7d（\u8c03\u8bd5\u671f）<\/span>
                                                      \n-XX:+TraceClassUnloading # \u76d1\u63a7\u7c7b\u5378\u8f7d<\/span><\/p>\n

                                                      # \u7c7b\u6cc4\u6f0f\u5feb\u901f\u8bca\u65ad<\/span>
                                                      \n-XX:+PrintClassHistogram # \u6309\u9700\u6253\u5370\u7c7b\u7edf\u8ba1<\/span>
                                                      \n-XX:+HeapDumpOnOutOfMemoryError # OOM\u81ea\u52a8dump<\/span>
                                                      \n-XX:HeapDumpPath=<\/span>\/tmp\/dumps\/<\/p>\n

                                                      \n

                                                      4.7 \u9762\u8bd5\u9ad8\u9891\u9898<\/h4>\n

                                                      Q1：\u5143\u7a7a\u95f4\u548c\u6c38\u4e45\u4ee3\u7684\u533a\u522b？<\/p>\n

                                                    • \u4f4d\u7f6e：\u6c38\u4e45\u4ee3\u5728\u5806\u5185，\u5143\u7a7a\u95f4\u5728\u672c\u5730\u5185\u5b58<\/li>\n
                                                    • \u5927\u5c0f：\u6c38\u4e45\u4ee3\u56fa\u5b9a\u4e0a\u9650，\u5143\u7a7a\u95f4\u53ef\u52a8\u6001\u6269\u5c55<\/li>\n
                                                    • GC：\u6c38\u4e45\u4ee3Full GC\u56de\u6536，\u5143\u7a7a\u95f4\u7531CMS\/G1\u56de\u6536<\/li>\n
                                                    • \u6ea2\u51fa：\u6c38\u4e45\u4ee3OOM: PermGen，\u5143\u7a7a\u95f4OOM: Metaspace<\/li>\n

                                                      Q2：\u52a8\u6001\u4ee3\u7406\u4e3a\u4ec0\u4e48\u4f1a\u5bfc\u81f4\u5143\u7a7a\u95f4\u6ea2\u51fa？<\/p>\n

                                                      \u6bcf\u6b21\u751f\u6210\u65b0\u4ee3\u7406\u7c7b\u90fd\u4f1a：<\/p>\n

                                                    • \u751f\u6210\u65b0\u7684.class\u5b57\u8282\u7801<\/li>\n
                                                    • \u52a0\u8f7d\u5230\u5143\u7a7a\u95f4（\u7c7b\u5143\u6570\u636e）<\/li>\n
                                                    • \u4e0d\u91ca\u653e\u5219\u7d2f\u79ef \u2192 \u5143\u7a7a\u95f4\u6ee1<\/li>\n

                                                      Q3：\u5982\u4f55\u76d1\u63a7\u5143\u7a7a\u95f4\u4f7f\u7528？<\/p>\n

                                                      MemoryMXBean<\/span> memoryBean =<\/span> ManagementFactory<\/span>.<\/span>getMemoryMXBean<\/span>(<\/span>)<\/span>;<\/span>
                                                      \nMemoryUsage<\/span> metaspaceUsage =<\/span> memoryBean.<\/span>getNonHeapMemoryUsage<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                      Q4：\u4e00\u4e2a\u4ee3\u7406\u7c7b\u5360\u7528\u591a\u5c11\u5143\u7a7a\u95f4？<\/p>\n

                                                        \n
                                                      • \u7b80\u5355\u4ee3\u7406\u7c7b \u2248 2-5KB<\/li>\n
                                                      • \u590d\u6742\u4ee3\u7406\u7c7b（\u591a\u65b9\u6cd5\/\u6ce8\u89e3） \u2248 5-10KB<\/li>\n
                                                      • 64MB \u2248 6000-30000\u4e2a\u7c7b<\/li>\n<\/ul>\n

                                                        Q5：\u7c7b\u52a0\u8f7d\u5668\u5728\u4ec0\u4e48\u65f6\u5019\u88ab\u56de\u6536？<\/p>\n

                                                        \u540c\u65f6\u6ee1\u8db3：<\/p>\n

                                                      • \u6240\u6709\u5b9e\u4f8b\u88ab\u56de\u6536<\/li>\n
                                                      • Class\u5bf9\u8c61\u65e0\u5f15\u7528<\/li>\n
                                                      • ClassLoader\u5bf9\u8c61\u65e0\u5f15\u7528<\/li>\n
                                                      • \u89e6\u53d1Full GC<\/li>\n
                                                        \n

                                                        \u4e94\u3001\u5b9e\u6218\u56db：\u76f4\u63a5\u5185\u5b58\u6ea2\u51fa \u2014\u2014 NIO Buffer\u672a\u91ca\u653e<\/h3>\n

                                                        \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                        5.1 \u590d\u73b0\u4ee3\u7801<\/h4>\n

                                                        package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2<\/span>;<\/span><\/p>\n

                                                        import<\/span> java.<\/span>nio.<\/span><\/span>ByteBuffer<\/span>;<\/span>
                                                        \nimport<\/span> java.<\/span>util.<\/span><\/span>ArrayList<\/span>;<\/span>
                                                        \nimport<\/span> java.<\/span>util.<\/span><\/span>List<\/span>;<\/span><\/p>\n

                                                        \/**
                                                        \n * \u573a\u666f：\u65e0\u9650\u5206\u914d\u5806\u5916\u5185\u5b58，\u672a\u624b\u52a8\u91ca\u653e
                                                        \n * JVM\u53c2\u6570：-XX:MaxDirectMemorySize=64m -XX:+PrintGCDetails
                                                        \n *\/<\/span>
                                                        \npublic<\/span> class<\/span> DirectBufferOOMDemo<\/span> {<\/span>
                                                        \n public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== \u76f4\u63a5\u5185\u5b58\u6ea2\u51fa\u6a21\u62df ==="<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u76f4\u63a5\u5185\u5b58\u9650\u5236: -XX:MaxDirectMemorySize=64m"<\/span>)<\/span>;<\/span><\/p>\n

                                                        List<\/span><<\/span>ByteBuffer<\/span>><\/span><\/span> buffers =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                                        \n int<\/span> count =<\/span> 0<\/span>;<\/span><\/p>\n

                                                        try<\/span> {<\/span>
                                                        \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                                        \n \/\/ \u5206\u914d1MB\u5806\u5916\u5185\u5b58<\/span>
                                                        \n ByteBuffer<\/span> buffer =<\/span> ByteBuffer<\/span>.<\/span>allocateDirect<\/span>(<\/span>1024<\/span> *<\/span> 1024<\/span>)<\/span>;<\/span>
                                                        \n buffers.<\/span>add<\/span>(<\/span>buffer)<\/span>;<\/span>
                                                        \n count++<\/span>;<\/span><\/p>\n

                                                        if<\/span> (<\/span>count %<\/span> 50<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5df2\u5206\u914d: %d MB (\u5806\u5916)%n"<\/span>,<\/span> count)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span> catch<\/span> (<\/span>OutOfMemoryError<\/span> e)<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\\\\n========== \u76f4\u63a5\u5185\u5b58\u6ea2\u51fa =========="<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u6700\u7ec8\u5206\u914d: %d MB%n"<\/span>,<\/span> count)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u9519\u8bef\u4fe1\u606f: %s%n"<\/span>,<\/span> e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                        \n e.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span>
                                                        \n}<\/span><\/p>\n

                                                        5.2 \u8fd0\u884c\u7ed3\u679c<\/h4>\n

                                                        5.3 \u89e3\u51b3\u65b9\u6848\u4e0e\u4ee3\u7801\u4fee\u590d<\/h4>\n

                                                        \u2705 \u65b9\u68481：\u624b\u52a8\u91ca\u653e（Cleaner）<\/h5>\n

                                                        public<\/span> class<\/span> DirectBuffer_Fix1_Cleaner<\/span> {<\/span>
                                                        \n public<\/span> static<\/span> void<\/span> safeAllocateAndFree<\/span>(<\/span>)<\/span> {<\/span>
                                                        \n ByteBuffer<\/span> buffer =<\/span> ByteBuffer<\/span>.<\/span>allocateDirect<\/span>(<\/span>1024<\/span> *<\/span> 1024<\/span>)<\/span>;<\/span>
                                                        \n try<\/span> {<\/span>
                                                        \n \/\/ \u4e1a\u52a1\u4f7f\u7528<\/span>
                                                        \n buffer.<\/span>putInt<\/span>(<\/span>1<\/span>)<\/span>;<\/span>
                                                        \n }<\/span> finally<\/span> {<\/span>
                                                        \n \/\/ \u624b\u52a8\u91ca\u653e\u76f4\u63a5\u5185\u5b58（JDK 8\/11\u517c\u5bb9）<\/span>
                                                        \n if<\/span> (<\/span>buffer.<\/span>isDirect<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                                        \n try<\/span> {<\/span>
                                                        \n Method<\/span> cleanerMethod =<\/span> buffer.<\/span>getClass<\/span>(<\/span>)<\/span>.<\/span>getMethod<\/span>(<\/span>"cleaner"<\/span>)<\/span>;<\/span>
                                                        \n cleanerMethod.<\/span>setAccessible<\/span>(<\/span>true<\/span>)<\/span>;<\/span>
                                                        \n Object<\/span> cleaner =<\/span> cleanerMethod.<\/span>invoke<\/span>(<\/span>buffer)<\/span>;<\/span>
                                                        \n if<\/span> (<\/span>cleaner !=<\/span> null<\/span>)<\/span> {<\/span>
                                                        \n cleaner.<\/span>getClass<\/span>(<\/span>)<\/span>.<\/span>getMethod<\/span>(<\/span>"clean"<\/span>)<\/span>.<\/span>invoke<\/span>(<\/span>cleaner)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span> catch<\/span> (<\/span>Exception<\/span> e)<\/span> {<\/span>
                                                        \n e.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span>
                                                        \n}<\/span><\/p>\n

                                                        \u2705 \u65b9\u68482：JDK9+\u4e13\u7528API<\/h5>\n

                                                        public<\/span> class<\/span> DirectBuffer_Fix2_JDK9<\/span> {<\/span>
                                                        \n \/\/ JDK 9+ \u63a8\u8350\u65b9\u5f0f<\/span>
                                                        \n public<\/span> static<\/span> void<\/span> safeFree<\/span>(<\/span>ByteBuffer<\/span> buffer)<\/span> {<\/span>
                                                        \n if<\/span> (<\/span>buffer.<\/span>isDirect<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                                        \n (<\/span>(<\/span>java.<\/span>nio.<\/span><\/span>DirectBuffer<\/span>)<\/span> buffer)<\/span>.<\/span>cleaner<\/span>(<\/span>)<\/span>.<\/span>clean<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span>
                                                        \n}<\/span><\/p>\n

                                                        \u2705 \u65b9\u68483：\u5bf9\u8c61\u6c60\u590d\u7528<\/h5>\n

                                                        public<\/span> class<\/span> DirectBuffer_Fix3_Pool<\/span> {<\/span>
                                                        \n private<\/span> static<\/span> final<\/span> Queue<\/span><<\/span>ByteBuffer<\/span>><\/span><\/span> BUFFER_POOL =<\/span>
                                                        \n new<\/span> ConcurrentLinkedQueue<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                                        \n private<\/span> static<\/span> final<\/span> int<\/span> POOL_SIZE =<\/span> 100<\/span>;<\/span>
                                                        \n private<\/span> static<\/span> final<\/span> int<\/span> BUFFER_SIZE =<\/span> 1024<\/span> *<\/span> 1024<\/span>;<\/span><\/p>\n

                                                        static<\/span> {<\/span>
                                                        \n \/\/ \u9884\u5206\u914d<\/span>
                                                        \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> POOL_SIZE;<\/span> i++<\/span>)<\/span> {<\/span>
                                                        \n BUFFER_POOL.<\/span>offer<\/span>(<\/span>ByteBuffer<\/span>.<\/span>allocateDirect<\/span>(<\/span>BUFFER_SIZE)<\/span>)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span><\/p>\n

                                                        public<\/span> static<\/span> ByteBuffer<\/span> borrow<\/span>(<\/span>)<\/span> {<\/span>
                                                        \n ByteBuffer<\/span> buffer =<\/span> BUFFER_POOL.<\/span>poll<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n return<\/span> buffer !=<\/span> null<\/span> ?<\/span> buffer :<\/span> ByteBuffer<\/span>.<\/span>allocateDirect<\/span>(<\/span>BUFFER_SIZE)<\/span>;<\/span>
                                                        \n }<\/span><\/p>\n

                                                        public<\/span> static<\/span> void<\/span> release<\/span>(<\/span>ByteBuffer<\/span> buffer)<\/span> {<\/span>
                                                        \n buffer.<\/span>clear<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n BUFFER_POOL.<\/span>offer<\/span>(<\/span>buffer)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n}<\/span><\/p>\n

                                                        \n

                                                        \u516d\u3001\u5b9e\u6218\u4e94：GC\u5f00\u9500\u8d85\u9650 \u2014\u2014 \u77ed\u547d\u5927\u5bf9\u8c61<\/h3>\n

                                                        \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                        6.1 \u590d\u73b0\u4ee3\u7801<\/h4>\n

                                                        package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2<\/span>;<\/span><\/p>\n

                                                        import<\/span> java.<\/span>lang.<\/span>management.<\/span><\/span>ManagementFactory<\/span>;<\/span>
                                                        \nimport<\/span> java.<\/span>lang.<\/span>management.<\/span><\/span>MemoryMXBean<\/span>;<\/span>
                                                        \nimport<\/span> java.<\/span>lang.<\/span>management.<\/span><\/span>MemoryUsage<\/span>;<\/span>
                                                        \nimport<\/span> java.<\/span>util.<\/span><\/span>ArrayList<\/span>;<\/span>
                                                        \nimport<\/span> java.<\/span>util.<\/span><\/span>List<\/span>;<\/span><\/p>\n

                                                        \/**
                                                        \n * \u573a\u666f：\u9891\u7e41\u521b\u5efa\u5927\u5bf9\u8c61 + \u90e8\u5206\u5bf9\u8c61\u4fdd\u6301\u5f15\u7528，\u5bfc\u81f4GC\u56de\u6536\u6548\u7387\u6781\u4f4e
                                                        \n *
                                                        \n * \u89e6\u53d1GC\u5f00\u9500\u8d85\u9650\u7684\u6761\u4ef6：
                                                        \n * 1. \u8017\u65f6：GC\u8017\u65f6 > 98% \u603bCPU\u65f6\u95f4
                                                        \n * 2. \u6548\u7387：\u6bcf\u6b21Full GC\u56de\u6536 < 2% \u5806\u5185\u5b58
                                                        \n * 3. \u8fde\u7eed：\u8fde\u7eed5\u6b21GC\u90fd\u6ee1\u8db3\u4e0a\u8ff0\u6761\u4ef6
                                                        \n *
                                                        \n * JVM\u53c2\u6570：-Xms200m -Xmx200m -XX:+UseParallelGC -XX:+PrintGCDetails -XX:+PrintGCTimeStamps
                                                        \n *\/<\/span>
                                                        \npublic<\/span> class<\/span> GCOverheadLimitReproduce<\/span> {<\/span><\/p>\n

                                                        \/\/ \u5927\u5bf9\u8c61\u9608\u503c：\u8d85\u8fc7\u8001\u5e74\u4ee3\u5269\u4f59\u7a7a\u95f4\u768480%<\/span>
                                                        \n private<\/span> static<\/span> final<\/span> int<\/span> BIG_OBJECT_SIZE =<\/span> 8<\/span> *<\/span> 1024<\/span> *<\/span> 1024<\/span>;<\/span> \/\/ 8MB<\/span>
                                                        \n private<\/span> static<\/span> final<\/span> int<\/span> HOLD_COUNT =<\/span> 5<\/span>;<\/span> \/\/ \u4fdd\u6301\u5f15\u7528\u7684\u5bf9\u8c61\u6570\u91cf<\/span><\/p>\n

                                                        \/\/ \u5b58\u6d3b\u5bf9\u8c61\u5217\u8868（\u6a21\u62df\u5185\u5b58\u6cc4\u6f0f）<\/span>
                                                        \n private<\/span> static<\/span> final<\/span> List<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> LIVE_OBJECTS =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                                        \n private<\/span> static<\/span> final<\/span> List<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> DEAD_OBJECTS =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                        public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> InterruptedException<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"========== GC\u5f00\u9500\u8d85\u9650\u6a21\u62df =========="<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5806\u5185\u5b58: -Xmx200m%n"<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5927\u5bf9\u8c61\u5927\u5c0f: %dMB (\u76f4\u63a5\u8fdb\u5165\u8001\u5e74\u4ee3)%n"<\/span>,<\/span> BIG_OBJECT_SIZE \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u4fdd\u6301\u5f15\u7528\u7684\u5bf9\u8c61\u6570: %d%n"<\/span>,<\/span> HOLD_COUNT)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"————————————-"<\/span>)<\/span>;<\/span><\/p>\n

                                                        \/\/ \u9884\u70ed：\u586b\u6ee1\u8001\u5e74\u4ee3\u5230\u4e34\u754c\u503c<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u9636\u6bb51: \u586b\u6ee1\u8001\u5e74\u4ee3…"<\/span>)<\/span>;<\/span>
                                                        \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> HOLD_COUNT;<\/span> i++<\/span>)<\/span> {<\/span>
                                                        \n LIVE_OBJECTS.<\/span>add<\/span>(<\/span>new<\/span> byte<\/span>[<\/span>BIG_OBJECT_SIZE]<\/span>)<\/span>;<\/span>
                                                        \n }<\/span><\/p>\n

                                                        MemoryMXBean<\/span> memoryBean =<\/span> ManagementFactory<\/span>.<\/span>getMemoryMXBean<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n int<\/span> count =<\/span> 0<\/span>;<\/span>
                                                        \n int<\/span> gcCount =<\/span> 0<\/span>;<\/span><\/p>\n

                                                        try<\/span> {<\/span>
                                                        \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                                        \n count++<\/span>;<\/span><\/p>\n

                                                        \/\/ 1. \u521b\u5efa\u5927\u5bf9\u8c61 – \u76f4\u63a5\u8fdb\u5165\u8001\u5e74\u4ee3<\/span>
                                                        \n byte<\/span>[<\/span>]<\/span> bigObject =<\/span> new<\/span> byte<\/span>[<\/span>BIG_OBJECT_SIZE]<\/span>;<\/span>
                                                        \n bigObject[<\/span>0<\/span>]<\/span> =<\/span> (<\/span>byte<\/span>)<\/span> count;<\/span> \/\/ \u9632\u6b62JIT\u4f18\u5316<\/span><\/p>\n

                                                        \/\/ 2. \u968f\u673a\u4fdd\u7559\u90e8\u5206\u5bf9\u8c61（\u6a21\u62df\u5185\u5b58\u788e\u7247）<\/span>
                                                        \n if<\/span> (<\/span>count %<\/span> 3<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                        \n LIVE_OBJECTS.<\/span>set<\/span>(<\/span>count %<\/span> HOLD_COUNT,<\/span> bigObject)<\/span>;<\/span>
                                                        \n }<\/span> else<\/span> {<\/span>
                                                        \n \/\/ \u5927\u90e8\u5206\u5bf9\u8c61\u5f88\u5feb\u5931\u53bb\u5f15\u7528<\/span>
                                                        \n bigObject =<\/span> null<\/span>;<\/span>
                                                        \n }<\/span><\/p>\n

                                                        \/\/ 3. \u624b\u52a8\u89e6\u53d1GC，\u89c2\u5bdf\u56de\u6536\u6548\u7387<\/span>
                                                        \n if<\/span> (<\/span>count %<\/span> 10<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>gc<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n gcCount++<\/span>;<\/span><\/p>\n

                                                        MemoryUsage<\/span> oldGen =<\/span> memoryBean.<\/span>getHeapMemoryUsage<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n long<\/span> used =<\/span> oldGen.<\/span>getUsed<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n long<\/span> max =<\/span> oldGen.<\/span>getMax<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n double<\/span> usageRatio =<\/span> (<\/span>double<\/span>)<\/span> used \/<\/span> max *<\/span> 100<\/span>;<\/span><\/p>\n

                                                        System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[\u7b2c%d\u8f6e] GC\u6b21\u6570: %d, \u8001\u5e74\u4ee3: %dMB\/%dMB (%.1f%%)%n"<\/span>,<\/span>
                                                        \n count,<\/span> gcCount,<\/span>
                                                        \n used \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>,<\/span>
                                                        \n max \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>,<\/span>
                                                        \n usageRatio)<\/span>;<\/span><\/p>\n

                                                        \/\/ \u68c0\u6d4bGC\u5f00\u9500\u8d85\u9650\u7684\u524d\u5146<\/span>
                                                        \n if<\/span> (<\/span>usageRatio ><\/span> 95<\/span>)<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>err.<\/span>println<\/span>(<\/span>"[\u8b66\u544a] \u8001\u5e74\u4ee3\u4f7f\u7528\u7387\u8d85\u8fc795%，\u5373\u5c06\u89e6\u53d1GC\u5f00\u9500\u8d85\u9650\u5f02\u5e38！"<\/span>)<\/span>;<\/span>
                                                        \n }<\/span><\/p>\n

                                                        Thread<\/span>.<\/span>sleep<\/span>(<\/span>50<\/span>)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span> catch<\/span> (<\/span>OutOfMemoryError<\/span> e)<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\\\\n========== \u5f02\u5e38\u6355\u83b7 =========="<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u9519\u8bef\u7c7b\u578b: %s%n"<\/span>,<\/span> e.<\/span>getClass<\/span>(<\/span>)<\/span>.<\/span>getSimpleName<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u9519\u8bef\u4fe1\u606f: %s%n"<\/span>,<\/span> e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u603b\u521b\u5efa\u5bf9\u8c61\u6570: %d%n"<\/span>,<\/span> count)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u89e6\u53d1GC\u6b21\u6570: %d%n"<\/span>,<\/span> gcCount)<\/span>;<\/span><\/p>\n

                                                        \/\/ \u6253\u5370\u6700\u7ec8\u5185\u5b58\u72b6\u6001<\/span>
                                                        \n MemoryUsage<\/span> heapUsage =<\/span> memoryBean.<\/span>getHeapMemoryUsage<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u6700\u7ec8\u5806\u5185\u5b58: %dMB\/%dMB%n"<\/span>,<\/span>
                                                        \n heapUsage.<\/span>getUsed<\/span>(<\/span>)<\/span> \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>,<\/span>
                                                        \n heapUsage.<\/span>getMax<\/span>(<\/span>)<\/span> \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span><\/p>\n

                                                        \/\/ \u6253\u5370\u8be6\u7ec6GC\u7edf\u8ba1<\/span>
                                                        \n printGCStatistics<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n e.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span><\/p>\n

                                                        private<\/span> static<\/span> void<\/span> printGCStatistics<\/span>(<\/span>)<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\\\\n——– GC\u7edf\u8ba1\u4fe1\u606f ——–"<\/span>)<\/span>;<\/span>
                                                        \n List<\/span><<\/span>java.<\/span>lang.<\/span>management.<\/span><\/span>GarbageCollectorMXBean<\/span>><\/span><\/span> gcBeans =<\/span>
                                                        \n ManagementFactory<\/span>.<\/span>getGarbageCollectorMXBeans<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                        for<\/span> (<\/span>java.<\/span>lang.<\/span>management.<\/span><\/span>GarbageCollectorMXBean<\/span> gc :<\/span> gcBeans)<\/span> {<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"GC\u540d\u79f0: %s%n"<\/span>,<\/span> gc.<\/span>getName<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>" \u6b21\u6570: %d%n"<\/span>,<\/span> gc.<\/span>getCollectionCount<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                        \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>" \u8017\u65f6: %d ms%n"<\/span>,<\/span> gc.<\/span>getCollectionTime<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                        \n }<\/span>
                                                        \n }<\/span>
                                                        \n}<\/span><\/p>\n

                                                        \n

                                                        6.2 \u8fd0\u884c\u7ed3\u679c\u5206\u6790<\/h4>\n

                                                        ========== GC\u5f00\u9500\u8d85\u9650\u6a21\u62df ==========
                                                        \n\u5806\u5185\u5b58: -Xmx200m
                                                        \n\u5927\u5bf9\u8c61\u5927\u5c0f: 8MB (\u76f4\u63a5\u8fdb\u5165\u8001\u5e74\u4ee3)
                                                        \n\u4fdd\u6301\u5f15\u7528\u7684\u5bf9\u8c61\u6570: 5
                                                        \n————————————-
                                                        \n\u9636\u6bb51: \u586b\u6ee1\u8001\u5e74\u4ee3…
                                                        \n[\u7b2c10\u8f6e] GC\u6b21\u6570: 1, \u8001\u5e74\u4ee3: 45MB\/200MB (22.5%)
                                                        \n[\u7b2c20\u8f6e] GC\u6b21\u6570: 2, \u8001\u5e74\u4ee3: 82MB\/200MB (41.0%)
                                                        \n[\u7b2c30\u8f6e] GC\u6b21\u6570: 3, \u8001\u5e74\u4ee3: 126MB\/200MB (63.0%)
                                                        \n[\u7b2c40\u8f6e] GC\u6b21\u6570: 4, \u8001\u5e74\u4ee3: 158MB\/200MB (79.0%)
                                                        \n[\u7b2c50\u8f6e] GC\u6b21\u6570: 5, \u8001\u5e74\u4ee3: 179MB\/200MB (89.5%)
                                                        \n[\u8b66\u544a] \u8001\u5e74\u4ee3\u4f7f\u7528\u7387\u8d85\u8fc795%，\u5373\u5c06\u89e6\u53d1GC\u5f00\u9500\u8d85\u9650\u5f02\u5e38！
                                                        \n[\u7b2c60\u8f6e] GC\u6b21\u6570: 6, \u8001\u5e74\u4ee3: 191MB\/200MB (95.5%)
                                                        \n[\u7b2c70\u8f6e] GC\u6b21\u6570: 7, \u8001\u5e74\u4ee3: 194MB\/200MB (97.0%)
                                                        \n[\u7b2c80\u8f6e] GC\u6b21\u6570: 8, \u8001\u5e74\u4ee3: 196MB\/200MB (98.0%)<\/p>\n

                                                        ========== \u5f02\u5e38\u6355\u83b7 ==========
                                                        \n\u9519\u8bef\u7c7b\u578b: OutOfMemoryError
                                                        \n\u9519\u8bef\u4fe1\u606f: GC overhead limit exceeded
                                                        \n\u603b\u521b\u5efa\u5bf9\u8c61\u6570: 87
                                                        \n\u89e6\u53d1GC\u6b21\u6570: 8
                                                        \n\u6700\u7ec8\u5806\u5185\u5b58: 196MB\/200MB<\/p>\n

                                                        GC\u65e5\u5fd7\u5206\u6790：<\/p>\n

                                                        [GC (Allocation Failure) 200M->198M(200M), 1.5320 secs]
                                                        \n[Full GC (System.gc()) 198M->196M(200M), 2.8450 secs]
                                                        \n[Full GC (Ergonomics) 196M->195M(200M), 2.9230 secs]
                                                        \n[Full GC (Allocation Failure) 195M->195M(200M), 3.0120 secs]<\/p>\n

                                                        \u5173\u952e\u6307\u6807：<\/p>\n

                                                          \n
                                                        • \u2705 GC\u8017\u65f6\u5360\u6bd4 \u2248 (1.5+2.8+2.9+3.0) \/ 30 \u2248 98.7%<\/li>\n
                                                        • \u2705 \u56de\u6536\u6548\u7387 \u2248 (200-196)\/200 = 2%<\/li>\n
                                                        • \u2705 \u8fde\u7eedGC\u6b21\u6570 = 5\u6b21<\/li>\n<\/ul>\n
                                                          \n

                                                          6.3 JVM\u6267\u884c\u8fc7\u7a0b\u56fe\u89e3<\/h4>\n

                                                          \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                          \n\u2502 GC\u5f00\u9500\u8d85\u9650\u89e6\u53d1\u8fc7\u7a0b \u2502
                                                          \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                          \n\u2502 \u9636\u6bb5 \u2502 \u5185\u5b58\u72b6\u6001 \u2502 GC\u884c\u4e3a \u2502 CPU\u5360\u6bd4 \u2502
                                                          \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                          \n\u2502 \u6b63\u5e38\u671f \u2502 Eden\u533a\u5feb\u901f\u5206\u914d \u2502 Minor GC \u2502 5-10% \u2502
                                                          \n\u2502 \u2502 \u8001\u5e74\u4ee3\u7a7a\u95f2 \u2502 1-10ms \u2502 \u2502
                                                          \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                          \n\u2502 \u664b\u5347\u671f \u2502 \u5927\u5bf9\u8c61\u2192\u8001\u5e74\u4ee3 \u2502 Major GC \u2502 30-50% \u2502
                                                          \n\u2502 \u2502 \u5b58\u6d3b\u5bf9\u8c61\u6ede\u7559 \u2502 100-500ms \u2502 \u2502
                                                          \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                          \n\u2502 \u8fc7\u8f7d\u671f \u2502 \u8001\u5e74\u4ee395%+ \u2502 Full GC \u2502 80-95% \u2502
                                                          \n\u2502 \u2502 \u56de\u6536\u7387＜5% \u2502 1-3s \u2502 \u2502
                                                          \n\u251c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524
                                                          \n\u2502 \u5d29\u6e83\u671f \u2502 GC\u8017\u65f6＞98% \u2502 \u8fde\u7eed\u5931\u8d25 \u2502 98%+ \u2502
                                                          \n\u2502 \u2502 GC overhead\u5f02\u5e38 \u2502 JVM\u629b\u51faOOM \u2502 \u2502
                                                          \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/p>\n

                                                          \u5185\u5b58\u6cc4\u6f0f\u5faa\u73af：
                                                          \n \u521b\u5efa\u5927\u5bf9\u8c61 \u2192 \u76f4\u63a5\u8fdb\u5165\u8001\u5e74\u4ee3 \u2192 \u8001\u5e74\u4ee3\u6ee1 \u2192 Full GC \u2192 \u56de\u6536\u6781\u5c11 \u2192
                                                          \n \u2191___________________________（\u91cd\u590d）___________________________\u2193<\/p>\n

                                                          \n

                                                          6.4 \u516d\u5957\u89e3\u51b3\u65b9\u6848<\/h4>\n

                                                          \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                          \u2705 \u65b9\u6848\u4e00：\u5bf9\u8c61\u6c60\u590d\u7528（\u6700\u6709\u6548）<\/h5>\n

                                                          \u9002\u7528\u4e8e：\u5927\u5bf9\u8c61\u9891\u7e41\u521b\u5efa\u4e14\u53ef\u590d\u7528\u7684\u573a\u666f<\/p>\n

                                                          package<\/span> com.<\/span>example.<\/span>aliyunDemo.<\/span>test.<\/span>jvm2.<\/span>fix<\/span>;<\/span><\/p>\n

                                                          import<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>ArrayBlockingQueue<\/span>;<\/span>
                                                          \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>BlockingQueue<\/span>;<\/span>
                                                          \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>TimeUnit<\/span>;<\/span>
                                                          \nimport<\/span> java.<\/span>util.<\/span>concurrent.<\/span>atomic.<\/span><\/span>AtomicInteger<\/span>;<\/span><\/p>\n

                                                          \/**
                                                          \n * \u89e3\u51b3\u65b9\u68481：\u5bf9\u8c61\u6c60\u5316 – \u907f\u514d\u9891\u7e41\u5206\u914d\/\u56de\u6536
                                                          \n * \u539f\u7406：\u590d\u7528\u5927\u5bf9\u8c61，\u51cf\u5c11GC\u538b\u529b
                                                          \n *\/<\/span>
                                                          \npublic<\/span> class<\/span> GCOverhead_Fix1_ObjectPool<\/span> {<\/span><\/p>\n

                                                          \/\/ \u5927\u5bf9\u8c61\u6c60<\/span>
                                                          \n private<\/span> static<\/span> final<\/span> BlockingQueue<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> OBJECT_POOL;<\/span>
                                                          \n private<\/span> static<\/span> final<\/span> int<\/span> POOL_SIZE =<\/span> 10<\/span>;<\/span>
                                                          \n private<\/span> static<\/span> final<\/span> int<\/span> OBJECT_SIZE =<\/span> 8<\/span> *<\/span> 1024<\/span> *<\/span> 1024<\/span>;<\/span> \/\/ 8MB<\/span>
                                                          \n private<\/span> static<\/span> final<\/span> AtomicInteger<\/span> BORROW_COUNT =<\/span> new<\/span> AtomicInteger<\/span>(<\/span>0<\/span>)<\/span>;<\/span>
                                                          \n private<\/span> static<\/span> final<\/span> AtomicInteger<\/span> HIT_COUNT =<\/span> new<\/span> AtomicInteger<\/span>(<\/span>0<\/span>)<\/span>;<\/span><\/p>\n

                                                          static<\/span> {<\/span>
                                                          \n \/\/ \u9884\u521b\u5efa\u5bf9\u8c61\u6c60<\/span>
                                                          \n OBJECT_POOL =<\/span> new<\/span> ArrayBlockingQueue<\/span><<\/span>><\/span><\/span>(<\/span>POOL_SIZE)<\/span>;<\/span>
                                                          \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> POOL_SIZE;<\/span> i++<\/span>)<\/span> {<\/span>
                                                          \n OBJECT_POOL.<\/span>offer<\/span>(<\/span>new<\/span> byte<\/span>[<\/span>OBJECT_SIZE]<\/span>)<\/span>;<\/span>
                                                          \n }<\/span>
                                                          \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[\u6c60\u521d\u59cb\u5316] \u5927\u5c0f: %d, \u5bf9\u8c61\u5927\u5c0f: %dMB%n"<\/span>,<\/span>
                                                          \n POOL_SIZE,<\/span> OBJECT_SIZE \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span>
                                                          \n }<\/span><\/p>\n

                                                          \/**
                                                          \n * \u4ece\u6c60\u4e2d\u501f\u7528\u5bf9\u8c61
                                                          \n *\/<\/span>
                                                          \n public<\/span> static<\/span> byte<\/span>[<\/span>]<\/span> borrowObject<\/span>(<\/span>)<\/span> {<\/span>
                                                          \n BORROW_COUNT.<\/span>incrementAndGet<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                          \/\/ \u975e\u963b\u585e\u83b7\u53d6<\/span>
                                                          \n byte<\/span>[<\/span>]<\/span> obj =<\/span> OBJECT_POOL.<\/span>poll<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                          if<\/span> (<\/span>obj !=<\/span> null<\/span>)<\/span> {<\/span>
                                                          \n HIT_COUNT.<\/span>incrementAndGet<\/span>(<\/span>)<\/span>;<\/span>
                                                          \n return<\/span> obj;<\/span>
                                                          \n }<\/span><\/p>\n

                                                          \/\/ \u6c60\u7a7a\u65f6\u521b\u5efa\u65b0\u5bf9\u8c61（\u5e94\u6025）<\/span>
                                                          \n return<\/span> new<\/span> byte<\/span>[<\/span>OBJECT_SIZE]<\/span>;<\/span>
                                                          \n }<\/span><\/p>\n

                                                          \/**
                                                          \n * \u5f52\u8fd8\u5bf9\u8c61\u5230\u6c60
                                                          \n *\/<\/span>
                                                          \n public<\/span> static<\/span> void<\/span> returnObject<\/span>(<\/span>byte<\/span>[<\/span>]<\/span> obj)<\/span> {<\/span>
                                                          \n if<\/span> (<\/span>obj !=<\/span> null<\/span> &&<\/span> obj.<\/span>length ==<\/span> OBJECT_SIZE)<\/span> {<\/span>
                                                          \n \/\/ \u6e05\u7a7a\u6570\u636e（\u907f\u514d\u5185\u5b58\u6cc4\u6f0f）<\/span>
                                                          \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> obj.<\/span>length;<\/span> i +=<\/span> 4096<\/span>)<\/span> {<\/span>
                                                          \n obj[<\/span>i]<\/span> =<\/span> 0<\/span>;<\/span>
                                                          \n }<\/span><\/p>\n

                                                          \/\/ \u975e\u963b\u585e\u5f52\u8fd8<\/span>
                                                          \n boolean<\/span> offered =<\/span> OBJECT_POOL.<\/span>offer<\/span>(<\/span>obj)<\/span>;<\/span>
                                                          \n if<\/span> (<\/span>!<\/span>offered)<\/span> {<\/span>
                                                          \n \/\/ \u6c60\u6ee1，\u4e22\u5f03\u5bf9\u8c61（GC\u56de\u6536）<\/span>
                                                          \n obj =<\/span> null<\/span>;<\/span>
                                                          \n }<\/span>
                                                          \n }<\/span>
                                                          \n }<\/span><\/p>\n

                                                          \/**
                                                          \n * \u81ea\u52a8\u5f52\u8fd8\u7684\u88c5\u9970\u5668
                                                          \n *\/<\/span>
                                                          \n public<\/span> static<\/span> <<\/span>T<\/span>><\/span><\/span> T<\/span> withPooledObject<\/span>(<\/span>PooledObjectCallback<\/span><<\/span>T<\/span>><\/span><\/span> callback)<\/span> {<\/span>
                                                          \n byte<\/span>[<\/span>]<\/span> obj =<\/span> borrowObject<\/span>(<\/span>)<\/span>;<\/span>
                                                          \n try<\/span> {<\/span>
                                                          \n return<\/span> callback.<\/span>execute<\/span>(<\/span>obj)<\/span>;<\/span>
                                                          \n }<\/span> finally<\/span> {<\/span>
                                                          \n returnObject<\/span>(<\/span>obj)<\/span>;<\/span>
                                                          \n }<\/span>
                                                          \n }<\/span><\/p>\n

                                                          @FunctionalInterface<\/span>
                                                          \n public<\/span> interface<\/span> PooledObjectCallback<\/span><<\/span>T<\/span>><\/span><\/span> {<\/span>
                                                          \n T<\/span> execute<\/span>(<\/span>byte<\/span>[<\/span>]<\/span> obj)<\/span>;<\/span>
                                                          \n }<\/span><\/p>\n

                                                          \/**
                                                          \n * \u7edf\u8ba1\u4fe1\u606f
                                                          \n *\/<\/span>
                                                          \n public<\/span> static<\/span> void<\/span> printStats<\/span>(<\/span>)<\/span> {<\/span>
                                                          \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[\u6c60\u7edf\u8ba1] \u501f\u7528\u6b21\u6570: %d, \u547d\u4e2d\u6b21\u6570: %d, \u547d\u4e2d\u7387: %.2f%%, \u6c60\u5927\u5c0f: %d%n"<\/span>,<\/span>
                                                          \n BORROW_COUNT.<\/span>get<\/span>(<\/span>)<\/span>,<\/span>
                                                          \n HIT_COUNT.<\/span>get<\/span>(<\/span>)<\/span>,<\/span>
                                                          \n BORROW_COUNT.<\/span>get<\/span>(<\/span>)<\/span> ==<\/span> 0<\/span> ?<\/span> 0<\/span> :<\/span> (<\/span>double<\/span>)<\/span> HIT_COUNT.<\/span>get<\/span>(<\/span>)<\/span> \/<\/span> BORROW_COUNT.<\/span>get<\/span>(<\/span>)<\/span> *<\/span> 100<\/span>,<\/span>
                                                          \n OBJECT_POOL.<\/span>size<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                          \n }<\/span><\/p>\n

                                                          public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> Exception<\/span> {<\/span>
                                                          \n \/\/ \u6d4b\u8bd5\u5bf9\u8c61\u6c60<\/span>
                                                          \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 1000<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>
                                                          \n String<\/span> result =<\/span> withPooledObject<\/span>(<\/span>obj -><\/span> {<\/span>
                                                          \n obj[<\/span>0<\/span>]<\/span> =<\/span> (<\/span>byte<\/span>)<\/span> i;<\/span>
                                                          \n return<\/span> "Processed: "<\/span> +<\/span> obj[<\/span>0<\/span>]<\/span>;<\/span>
                                                          \n }<\/span>)<\/span>;<\/span><\/p>\n

                                                          if<\/span> (<\/span>i %<\/span> 200<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                          \n printStats<\/span>(<\/span>)<\/span>;<\/span>
                                                          \n }<\/span>
                                                          \n Thread<\/span>.<\/span>sleep<\/span>(<\/span>10<\/span>)<\/span>;<\/span>
                                                          \n }<\/span>
                                                          \n printStats<\/span>(<\/span>)<\/span>;<\/span>
                                                          \n }<\/span>
                                                          \n}<\/span><\/p>\n

                                                          \u4f18\u52bf：<\/p>\n

                                                            \n
                                                          • \u2705 \u96f6GC – \u5bf9\u8c61\u590d\u7528，\u4e0d\u4ea7\u751f\u5783\u573e<\/li>\n
                                                          • \u2705 \u9ad8\u6027\u80fd – \u547d\u4e2d\u738790%+，\u65e0\u5206\u914d\u5f00\u9500<\/li>\n
                                                          • \u2705 \u53ef\u63a7 – \u6c60\u5927\u5c0f\u7cbe\u786e\u63a7\u5236<\/li>\n<\/ul>\n
                                                            \n
                                                            \u2705 \u65b9\u6848\u4e8c：\u8c03\u6574\u5927\u5bf9\u8c61\u9608\u503c（PretenureSizeThreshold）<\/h5>\n

                                                            \u9002\u7528\u4e8e：CMS\/ParNew\u5783\u573e\u6536\u96c6\u5668<\/p>\n

                                                            # JVM\u53c2\u6570\u4f18\u5316\u65b9\u6848<\/span>
                                                            \n-XX:+UseParNewGC # \u4f7f\u7528ParNew\u6536\u96c6\u5668<\/span>
                                                            \n-XX:+UseConcMarkSweepGC # \u4f7f\u7528CMS\u6536\u96c6\u5668<\/span>
                                                            \n-XX:PretenureSizeThreshold=<\/span>10m # 10MB\u4ee5\u4e0a\u624d\u76f4\u63a5\u8fdb\u5165\u8001\u5e74\u4ee3<\/span>
                                                            \n-XX:MaxTenuringThreshold=<\/span>15<\/span> # \u6700\u5927\u664b\u5347\u9608\u503c<\/span>
                                                            \n-XX:+PrintTenuringDistribution # \u6253\u5370\u5e74\u9f84\u5206\u5e03<\/span><\/p>\n

                                                            \u9a8c\u8bc1\u4ee3\u7801：<\/p>\n

                                                            \/**
                                                            \n * \u89e3\u51b3\u65b9\u68482：\u5927\u5bf9\u8c61\u9608\u503c\u8c03\u6574
                                                            \n * \u9a8c\u8bc1\u5bf9\u8c61\u662f\u5426\u8fdb\u5165\u8001\u5e74\u4ee3
                                                            \n *\/<\/span>
                                                            \npublic<\/span> class<\/span> GCOverhead_Fix2_PretenureSize<\/span> {<\/span>
                                                            \n private<\/span> static<\/span> final<\/span> int<\/span> OBJECT_SIZE =<\/span> 8<\/span> *<\/span> 1024<\/span> *<\/span> 1024<\/span>;<\/span> \/\/ 8MB<\/span><\/p>\n

                                                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== \u9a8c\u8bc1PretenureSizeThreshold ==="<\/span>)<\/span>;<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5bf9\u8c61\u5927\u5c0f: %dMB%n"<\/span>,<\/span> OBJECT_SIZE \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u9608\u503c\u8bbe\u7f6e: -XX:PretenureSizeThreshold=10m%n"<\/span>)<\/span>;<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"8MB < 10MB \u2192 \u5e94\u5728Eden\u5206\u914d"<\/span>)<\/span>;<\/span><\/p>\n

                                                            \/\/ \u5206\u914d\u5bf9\u8c61<\/span>
                                                            \n byte<\/span>[<\/span>]<\/span> bigObject =<\/span> new<\/span> byte<\/span>[<\/span>OBJECT_SIZE]<\/span>;<\/span>
                                                            \n bigObject[<\/span>0<\/span>]<\/span> =<\/span> 1<\/span>;<\/span><\/p>\n

                                                            \/\/ \u5f3a\u5236GC<\/span>
                                                            \n System<\/span>.<\/span>gc<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u9a8c\u8bc1\u5b8c\u6210，\u68c0\u67e5GC\u65e5\u5fd7\u786e\u8ba4\u5206\u914d\u533a\u57df"<\/span>)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n}<\/span><\/p>\n

                                                            GC\u65e5\u5fd7\u89e3\u8bfb：<\/p>\n

                                                            # \u8c03\u6574\u524d：\u76f4\u63a5\u8fdb\u5165\u8001\u5e74\u4ee3
                                                            \n[GC (Allocation Failure) DefNew: 2795K->0K(39296K) 2795K->2728K(126720K), 0.0032058 secs]
                                                            \n[Times: user=0.00 sys=0.00, real=0.00 secs] <\/p>\n

                                                            # \u8c03\u6574\u540e：\u5728Eden\u5206\u914d
                                                            \n[GC (Allocation Failure) DefNew: 39296K->512K(39296K), 0.0045120 secs]
                                                            \n[Times: user=0.02 sys=0.00, real=0.00 secs]<\/p>\n

                                                            \n
                                                            \u2705 \u65b9\u6848\u4e09：\u8c03\u6574GC\u6536\u96c6\u5668（G1\/ZGC）<\/h5>\n

                                                            \u9002\u7528\u4e8e：\u5927\u5185\u5b58\u670d\u52a1（>4GB）\u548c\u4f4e\u5ef6\u8fdf\u8981\u6c42<\/p>\n

                                                            # G1\u6536\u96c6\u5668\u914d\u7f6e<\/span>
                                                            \n-XX:+UseG1GC
                                                            \n-XX:G1HeapRegionSize=<\/span>16m # \u533a\u57df\u5927\u5c0f（\u5927\u5bf9\u8c61\u76f4\u63a5\u5206\u914d）<\/span>
                                                            \n-XX:G1ReservePercent=<\/span>15<\/span> # \u9884\u7559\u7a7a\u95f4<\/span>
                                                            \n-XX:InitiatingHeapOccupancyPercent=<\/span>45<\/span> # \u89e6\u53d1\u5e76\u53d1GC\u9608\u503c<\/span>
                                                            \n-XX:ConcGCThreads=<\/span>4<\/span> # \u5e76\u53d1GC\u7ebf\u7a0b\u6570<\/span><\/p>\n

                                                            # ZGC\u6536\u96c6\u5668\u914d\u7f6e（JDK 11+）<\/span>
                                                            \n-XX:+UseZGC
                                                            \n-XX:ConcGCThreads=<\/span>2<\/span>
                                                            \n-XX:ZCollectionInterval=<\/span>120<\/span><\/p>\n

                                                            G1\u5927\u5bf9\u8c61\u5206\u914d\u4f18\u5316：<\/p>\n

                                                            \/**
                                                            \n * \u89e3\u51b3\u65b9\u68483：G1\u6536\u96c6\u5668\u4f18\u5316
                                                            \n *\/<\/span>
                                                            \npublic<\/span> class<\/span> GCOverhead_Fix3_G1Optimization<\/span> {<\/span><\/p>\n

                                                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                            \n \/\/ \u901a\u8fc7JVM\u53c2\u6570\u8bbe\u7f6e，\u65e0\u9700\u4ee3\u7801\u4fee\u6539<\/span><\/p>\n

                                                            \/\/ \u76d1\u63a7G1\u5927\u5bf9\u8c61\u5206\u914d<\/span>
                                                            \n ManagementFactory<\/span>.<\/span>getMemoryPoolMXBeans<\/span>(<\/span>)<\/span>.<\/span>stream<\/span>(<\/span>)<\/span>
                                                            \n .<\/span>filter<\/span>(<\/span>pool -><\/span> pool.<\/span>getName<\/span>(<\/span>)<\/span>.<\/span>contains<\/span>(<\/span>"G1 Humongous"<\/span>)<\/span>)<\/span>
                                                            \n .<\/span>findFirst<\/span>(<\/span>)<\/span>
                                                            \n .<\/span>ifPresent<\/span>(<\/span>pool -><\/span> {<\/span>
                                                            \n MemoryUsage<\/span> usage =<\/span> pool.<\/span>getUsage<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"G1\u5927\u5bf9\u8c61\u533a: %dMB\/%dMB%n"<\/span>,<\/span>
                                                            \n usage.<\/span>getUsed<\/span>(<\/span>)<\/span> \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>,<\/span>
                                                            \n usage.<\/span>getCommitted<\/span>(<\/span>)<\/span> \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span>
                                                            \n }<\/span>)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n}<\/span><\/p>\n

                                                            \n
                                                            \u2705 \u65b9\u6848\u56db：\u5bf9\u8c61\u5927\u5c0f\u62c6\u5206<\/h5>\n

                                                            \u9002\u7528\u4e8e：\u4e1a\u52a1\u5141\u8bb8\u62c6\u5206\u7684\u5927\u5bf9\u8c61\u573a\u666f<\/p>\n

                                                            \/**
                                                            \n * \u89e3\u51b3\u65b9\u68484：\u5927\u5bf9\u8c61\u62c6\u5206\u4e3a\u5c0f\u5bf9\u8c61
                                                            \n * \u539f\u7406：8MB \u2192 8\u4e2a1MB，\u907f\u514d\u76f4\u63a5\u8fdb\u5165\u8001\u5e74\u4ee3
                                                            \n *\/<\/span>
                                                            \npublic<\/span> class<\/span> GCOverhead_Fix4_SplitObject<\/span> {<\/span><\/p>\n

                                                            \/\/ \u539f\u59cb：\u5355\u4e00\u5927\u5bf9\u8c61<\/span>
                                                            \n \/\/ byte[] large = new byte[8 * 1024 * 1024];<\/span><\/p>\n

                                                            \/\/ \u4f18\u5316：\u62c6\u5206\u4e3a\u5c0f\u5bf9\u8c61\u6570\u7ec4<\/span>
                                                            \n private<\/span> static<\/span> final<\/span> int<\/span> CHUNK_SIZE =<\/span> 1024<\/span> *<\/span> 1024<\/span>;<\/span> \/\/ 1MB<\/span>
                                                            \n private<\/span> static<\/span> final<\/span> int<\/span> CHUNK_COUNT =<\/span> 8<\/span>;<\/span> \/\/ 8\u4e2a<\/span><\/p>\n

                                                            public<\/span> static<\/span> class<\/span> SplitBuffer<\/span> {<\/span>
                                                            \n private<\/span> final<\/span> byte<\/span>[<\/span>]<\/span>[<\/span>]<\/span> chunks =<\/span> new<\/span> byte<\/span>[<\/span>CHUNK_COUNT]<\/span>[<\/span>]<\/span>;<\/span><\/p>\n

                                                            public<\/span> SplitBuffer<\/span>(<\/span>)<\/span> {<\/span>
                                                            \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> CHUNK_COUNT;<\/span> i++<\/span>)<\/span> {<\/span>
                                                            \n chunks[<\/span>i]<\/span> =<\/span> new<\/span> byte<\/span>[<\/span>CHUNK_SIZE]<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span><\/p>\n

                                                            public<\/span> void<\/span> setByte<\/span>(<\/span>int<\/span> index,<\/span> byte<\/span> value)<\/span> {<\/span>
                                                            \n int<\/span> chunkIndex =<\/span> index \/<\/span> CHUNK_SIZE;<\/span>
                                                            \n int<\/span> offset =<\/span> index %<\/span> CHUNK_SIZE;<\/span>
                                                            \n if<\/span> (<\/span>chunkIndex <<\/span> CHUNK_COUNT)<\/span> {<\/span>
                                                            \n chunks[<\/span>chunkIndex]<\/span>[<\/span>offset]<\/span> =<\/span> value;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span><\/p>\n

                                                            public<\/span> byte<\/span> getByte<\/span>(<\/span>int<\/span> index)<\/span> {<\/span>
                                                            \n int<\/span> chunkIndex =<\/span> index \/<\/span> CHUNK_SIZE;<\/span>
                                                            \n int<\/span> offset =<\/span> index %<\/span> CHUNK_SIZE;<\/span>
                                                            \n if<\/span> (<\/span>chunkIndex <<\/span> CHUNK_COUNT)<\/span> {<\/span>
                                                            \n return<\/span> chunks[<\/span>chunkIndex]<\/span>[<\/span>offset]<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n return<\/span> 0<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            public<\/span> void<\/span> clear<\/span>(<\/span>)<\/span> {<\/span>
                                                            \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> CHUNK_COUNT;<\/span> i++<\/span>)<\/span> {<\/span>
                                                            \n chunks[<\/span>i]<\/span> =<\/span> null<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span><\/p>\n

                                                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                            \n \/\/ \u4f7f\u7528\u62c6\u5206\u5bf9\u8c61<\/span>
                                                            \n SplitBuffer<\/span> buffer =<\/span> new<\/span> SplitBuffer<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n buffer.<\/span>setByte<\/span>(<\/span>5_000_000<\/span>,<\/span> (<\/span>byte<\/span>)<\/span> 100<\/span>)<\/span>;<\/span> \/\/ \u57285MB\u4f4d\u7f6e\u5199\u5165<\/span><\/p>\n

                                                            \/\/ \u4e0d\u518d\u4f7f\u7528\u65f6\u91ca\u653e<\/span>
                                                            \n buffer.<\/span>clear<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n}<\/span><\/p>\n

                                                            \n
                                                            \u2705 \u65b9\u6848\u4e94：\u76f4\u63a5\u5185\u5b58（DirectBuffer）<\/h5>\n

                                                            \u9002\u7528\u4e8e：\u7f51\u7edc\u4f20\u8f93\u3001\u6587\u4ef6IO\u7b49\u573a\u666f，\u5806\u5916\u5185\u5b58<\/p>\n

                                                            \/**
                                                            \n * \u89e3\u51b3\u65b9\u68485：\u76f4\u63a5\u5185\u5b58\u5206\u914d
                                                            \n * \u539f\u7406：\u5806\u5916\u5185\u5b58，\u4e0d\u5360\u7528\u8001\u5e74\u4ee3\u7a7a\u95f4
                                                            \n *
                                                            \n * JVM\u53c2\u6570：-XX:MaxDirectMemorySize=512m
                                                            \n *\/<\/span>
                                                            \npublic<\/span> class<\/span> GCOverhead_Fix5_DirectMemory<\/span> {<\/span><\/p>\n

                                                            private<\/span> static<\/span> final<\/span> int<\/span> BUFFER_SIZE =<\/span> 8<\/span> *<\/span> 1024<\/span> *<\/span> 1024<\/span>;<\/span> \/\/ 8MB<\/span>
                                                            \n private<\/span> static<\/span> final<\/span> List<\/span><<\/span>java.<\/span>nio.<\/span><\/span>ByteBuffer<\/span>><\/span><\/span> BUFFERS =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                            \/**
                                                            \n * \u5206\u914d\u76f4\u63a5\u5185\u5b58
                                                            \n *\/<\/span>
                                                            \n public<\/span> static<\/span> java.<\/span>nio.<\/span><\/span>ByteBuffer<\/span> allocateDirect<\/span>(<\/span>)<\/span> {<\/span>
                                                            \n return<\/span> java.<\/span>nio.<\/span><\/span>ByteBuffer<\/span>.<\/span>allocateDirect<\/span>(<\/span>BUFFER_SIZE)<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            \/**
                                                            \n * \u5b89\u5168\u91ca\u653e\u76f4\u63a5\u5185\u5b58
                                                            \n *\/<\/span>
                                                            \n public<\/span> static<\/span> void<\/span> freeDirect<\/span>(<\/span>java.<\/span>nio.<\/span><\/span>ByteBuffer<\/span> buffer)<\/span> {<\/span>
                                                            \n if<\/span> (<\/span>buffer.<\/span>isDirect<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                                            \n \/\/ JDK 9+ \u53ef\u4ee5\u4f7f\u7528 Cleaner<\/span>
                                                            \n try<\/span> {<\/span>
                                                            \n java.<\/span>lang.<\/span>reflect.<\/span><\/span>Method<\/span> cleanerMethod =<\/span>
                                                            \n buffer.<\/span>getClass<\/span>(<\/span>)<\/span>.<\/span>getMethod<\/span>(<\/span>"cleaner"<\/span>)<\/span>;<\/span>
                                                            \n cleanerMethod.<\/span>setAccessible<\/span>(<\/span>true<\/span>)<\/span>;<\/span>
                                                            \n Object<\/span> cleaner =<\/span> cleanerMethod.<\/span>invoke<\/span>(<\/span>buffer)<\/span>;<\/span>
                                                            \n if<\/span> (<\/span>cleaner !=<\/span> null<\/span>)<\/span> {<\/span>
                                                            \n cleaner.<\/span>getClass<\/span>(<\/span>)<\/span>.<\/span>getMethod<\/span>(<\/span>"clean"<\/span>)<\/span>
                                                            \n .<\/span>invoke<\/span>(<\/span>cleaner)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span> catch<\/span> (<\/span>Exception<\/span> e)<\/span> {<\/span>
                                                            \n \/\/ \u964d\u7ea7：\u7b49\u5f85GC\u56de\u6536<\/span>
                                                            \n buffer =<\/span> null<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span><\/p>\n

                                                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== \u76f4\u63a5\u5185\u5b58\u6d4b\u8bd5 ==="<\/span>)<\/span>;<\/span><\/p>\n

                                                            \/\/ \u5206\u914d\u76f4\u63a5\u5185\u5b58<\/span>
                                                            \n java.<\/span>nio.<\/span><\/span>ByteBuffer<\/span> directBuf =<\/span> allocateDirect<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n directBuf.<\/span>putInt<\/span>(<\/span>100<\/span>)<\/span>;<\/span><\/p>\n

                                                            \/\/ \u8bfb\u53d6\u6570\u636e<\/span>
                                                            \n directBuf.<\/span>flip<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n int<\/span> value =<\/span> directBuf.<\/span>getInt<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u76f4\u63a5\u5185\u5b58\u8bfb\u53d6: %d%n"<\/span>,<\/span> value)<\/span>;<\/span><\/p>\n

                                                            \/\/ \u663e\u5f0f\u91ca\u653e<\/span>
                                                            \n freeDirect<\/span>(<\/span>directBuf)<\/span>;<\/span><\/p>\n

                                                            \/\/ \u76d1\u63a7\u76f4\u63a5\u5185\u5b58\u4f7f\u7528<\/span>
                                                            \n try<\/span> {<\/span>
                                                            \n java.<\/span>lang.<\/span>management.<\/span><\/span>BufferPoolMXBean<\/span> directPool =<\/span>
                                                            \n ManagementFactory<\/span>.<\/span>getPlatformMXBeans<\/span>(<\/span>
                                                            \n java.<\/span>lang.<\/span>management.<\/span><\/span>BufferPoolMXBean<\/span>.<\/span>class<\/span>)<\/span>
                                                            \n .<\/span>stream<\/span>(<\/span>)<\/span>
                                                            \n .<\/span>filter<\/span>(<\/span>pool -><\/span> pool.<\/span>getName<\/span>(<\/span>)<\/span>.<\/span>contains<\/span>(<\/span>"direct"<\/span>)<\/span>)<\/span>
                                                            \n .<\/span>findFirst<\/span>(<\/span>)<\/span>
                                                            \n .<\/span>orElse<\/span>(<\/span>null<\/span>)<\/span>;<\/span><\/p>\n

                                                            if<\/span> (<\/span>directPool !=<\/span> null<\/span>)<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u76f4\u63a5\u5185\u5b58\u4f7f\u7528: %dMB%n"<\/span>,<\/span>
                                                            \n directPool.<\/span>getMemoryUsed<\/span>(<\/span>)<\/span> \/<\/span> 1024<\/span> \/<\/span> 1024<\/span>)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span> catch<\/span> (<\/span>Exception<\/span> e)<\/span> {<\/span>
                                                            \n \/\/ JDK 8\u4e0d\u652f\u6301<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span>
                                                            \n}<\/span><\/p>\n

                                                            \u4f18\u7f3a\u70b9：<\/p>\n\n\u7279\u6027\u5806\u5185\u5b58\u76f4\u63a5\u5185\u5b58<\/tr>\n\n\n\n\n\n\n
                                                            \u5206\u914d\u901f\u5ea6<\/td>\n\u5feb<\/td>\n\u6162（10\u500d）<\/td>\n<\/tr>\n
                                                            GC\u5f71\u54cd<\/td>\n\u6709<\/td>\n\u65e0<\/td>\n<\/tr>\n
                                                            IO\u6548\u7387<\/td>\n\u9700\u62f7\u8d1d<\/td>\n\u96f6\u62f7\u8d1d<\/td>\n<\/tr>\n
                                                            \u5185\u5b58\u4e0a\u9650<\/td>\n-Xmx<\/td>\n-XX:MaxDirectMemorySize<\/td>\n<\/tr>\n
                                                            \u91ca\u653e\u63a7\u5236<\/td>\n\u81ea\u52a8GC<\/td>\n\u624b\u52a8\/GC<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
                                                            \n
                                                            \u2705 \u65b9\u6848\u516d：\u8f6f\u5f15\u7528\u7f13\u5b58（\u5185\u5b58\u654f\u611f）<\/h5>\n

                                                            \u9002\u7528\u4e8e：\u53ef\u91cd\u5efa\u7684\u5927\u5bf9\u8c61，\u5185\u5b58\u7d27\u5f20\u65f6\u81ea\u52a8\u91ca\u653e<\/p>\n

                                                            \/**
                                                            \n * \u89e3\u51b3\u65b9\u68486：\u8f6f\u5f15\u7528\u5927\u5bf9\u8c61
                                                            \n * \u539f\u7406：\u5185\u5b58\u4e0d\u8db3\u65f6GC\u81ea\u52a8\u56de\u6536
                                                            \n *\/<\/span>
                                                            \npublic<\/span> class<\/span> GCOverhead_Fix6_SoftReference<\/span> {<\/span><\/p>\n

                                                            private<\/span> static<\/span> final<\/span> int<\/span> CACHE_SIZE =<\/span> 5<\/span>;<\/span>
                                                            \n private<\/span> static<\/span> final<\/span> int<\/span> OBJECT_SIZE =<\/span> 8<\/span> *<\/span> 1024<\/span> *<\/span> 1024<\/span>;<\/span> \/\/ 8MB<\/span><\/p>\n

                                                            \/\/ \u8f6f\u5f15\u7528\u7f13\u5b58<\/span>
                                                            \n private<\/span> static<\/span> final<\/span> List<\/span><<\/span>java.<\/span>lang.<\/span>ref.<\/span><\/span>SoftReference<\/span><<\/span>byte<\/span>[<\/span>]<\/span>>><\/span> CACHE =<\/span>
                                                            \n new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                            \/**
                                                            \n * \u6dfb\u52a0\u5230\u8f6f\u5f15\u7528\u7f13\u5b58
                                                            \n *\/<\/span>
                                                            \n public<\/span> static<\/span> void<\/span> addToCache<\/span>(<\/span>byte<\/span>[<\/span>]<\/span> data)<\/span> {<\/span>
                                                            \n \/\/ \u6e05\u7406\u5df2\u56de\u6536\u7684\u5f15\u7528<\/span>
                                                            \n CACHE.<\/span>removeIf<\/span>(<\/span>ref -><\/span> ref.<\/span>get<\/span>(<\/span>)<\/span> ==<\/span> null<\/span>)<\/span>;<\/span><\/p>\n

                                                            \/\/ \u4fdd\u6301\u7f13\u5b58\u5927\u5c0f<\/span>
                                                            \n while<\/span> (<\/span>CACHE.<\/span>size<\/span>(<\/span>)<\/span> >=<\/span> CACHE_SIZE)<\/span> {<\/span>
                                                            \n CACHE.<\/span>remove<\/span>(<\/span>0<\/span>)<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            \/\/ \u6dfb\u52a0\u8f6f\u5f15\u7528<\/span>
                                                            \n CACHE.<\/span>add<\/span>(<\/span>new<\/span> java.<\/span>lang.<\/span>ref.<\/span><\/span>SoftReference<\/span><<\/span>><\/span><\/span>(<\/span>data)<\/span>)<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            \/**
                                                            \n * \u4ece\u7f13\u5b58\u83b7\u53d6
                                                            \n *\/<\/span>
                                                            \n public<\/span> static<\/span> byte<\/span>[<\/span>]<\/span> getFromCache<\/span>(<\/span>int<\/span> index)<\/span> {<\/span>
                                                            \n if<\/span> (<\/span>index <<\/span> CACHE.<\/span>size<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
                                                            \n java.<\/span>lang.<\/span>ref.<\/span><\/span>SoftReference<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> ref =<\/span> CACHE.<\/span>get<\/span>(<\/span>index)<\/span>;<\/span>
                                                            \n byte<\/span>[<\/span>]<\/span> data =<\/span> ref.<\/span>get<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n if<\/span> (<\/span>data !=<\/span> null<\/span>)<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[\u7f13\u5b58\u547d\u4e2d] \u7d22\u5f15: %d%n"<\/span>,<\/span> index)<\/span>;<\/span>
                                                            \n return<\/span> data;<\/span>
                                                            \n }<\/span> else<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[\u7f13\u5b58\u5931\u6548] \u7d22\u5f15: %d (\u88abGC\u56de\u6536)%n"<\/span>,<\/span> index)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span>
                                                            \n return<\/span> null<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            \/**
                                                            \n * \u76d1\u63a7\u8f6f\u5f15\u7528\u56de\u6536
                                                            \n *\/<\/span>
                                                            \n public<\/span> static<\/span> void<\/span> monitorSoftReferences<\/span>(<\/span>)<\/span> {<\/span>
                                                            \n \/\/ \u4e3b\u52a8\u89e6\u53d1GC（\u4ec5\u4e3a\u6f14\u793a）<\/span>
                                                            \n System<\/span>.<\/span>gc<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                            int<\/span> activeCount =<\/span> 0<\/span>;<\/span>
                                                            \n for<\/span> (<\/span>java.<\/span>lang.<\/span>ref.<\/span><\/span>SoftReference<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> ref :<\/span> CACHE)<\/span> {<\/span>
                                                            \n if<\/span> (<\/span>ref.<\/span>get<\/span>(<\/span>)<\/span> !=<\/span> null<\/span>)<\/span> {<\/span>
                                                            \n activeCount++<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span><\/p>\n

                                                            System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"[\u76d1\u63a7] \u7f13\u5b58\u603b\u5927\u5c0f: %d, \u5b58\u6d3b: %d, \u56de\u6536: %d%n"<\/span>,<\/span>
                                                            \n CACHE.<\/span>size<\/span>(<\/span>)<\/span>,<\/span> activeCount,<\/span> CACHE.<\/span>size<\/span>(<\/span>)<\/span> –<\/span> activeCount)<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> Exception<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== \u8f6f\u5f15\u7528\u5927\u5bf9\u8c61\u7f13\u5b58 ==="<\/span>)<\/span>;<\/span><\/p>\n

                                                            \/\/ \u6dfb\u52a0\u5927\u5bf9\u8c61\u5230\u7f13\u5b58<\/span>
                                                            \n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 10<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>
                                                            \n addToCache<\/span>(<\/span>new<\/span> byte<\/span>[<\/span>OBJECT_SIZE]<\/span>)<\/span>;<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u6dfb\u52a0\u7b2c%d\u4e2a\u5927\u5bf9\u8c61\u5230\u7f13\u5b58%n"<\/span>,<\/span> i +<\/span> 1<\/span>)<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            monitorSoftReferences<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                            \/\/ \u6a21\u62df\u5185\u5b58\u538b\u529b<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\\\\n\u6a21\u62df\u5185\u5b58\u538b\u529b…"<\/span>)<\/span>;<\/span>
                                                            \n List<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> pressure =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                                            \n try<\/span> {<\/span>
                                                            \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                                            \n pressure.<\/span>add<\/span>(<\/span>new<\/span> byte<\/span>[<\/span>OBJECT_SIZE]<\/span>)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span> catch<\/span> (<\/span>OutOfMemoryError<\/span> e)<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u5185\u5b58\u538b\u529b\u89e6\u53d1，\u8f6f\u5f15\u7528\u88ab\u56de\u6536"<\/span>)<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            monitorSoftReferences<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n}<\/span><\/p>\n

                                                            \n

                                                            6.5 \u65b9\u6848\u5bf9\u6bd4\u4e0e\u9009\u578b\u5efa\u8bae<\/h4>\n\n\u5bf9\u6bd4\u7ef4\u5ea6\u65b9\u68481 \u5bf9\u8c61\u6c60\u65b9\u68482 \u9608\u503c\u8c03\u6574\u65b9\u68483 G1\/ZGC\u65b9\u68484 \u62c6\u5206\u65b9\u68485 \u76f4\u63a5\u5185\u5b58\u65b9\u68486 \u8f6f\u5f15\u7528<\/tr>\n\n\n\n\n\n\n
                                                            GC\u538b\u529b<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50 \u6781\u4f4e<\/td>\n\u2b50\u2b50\u2b50 \u4e2d\u7b49<\/td>\n\u2b50\u2b50\u2b50\u2b50 \u4f4e<\/td>\n\u2b50\u2b50\u2b50 \u4e2d\u7b49<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50 \u65e0<\/td>\n\u2b50\u2b50\u2b50\u2b50 \u4f4e<\/td>\n<\/tr>\n
                                                            \u5b9e\u73b0\u96be\u5ea6<\/td>\n\u2b50\u2b50\u2b50 \u4e2d\u7b49<\/td>\n\u2b50 \u7b80\u5355<\/td>\n\u2b50 \u7b80\u5355<\/td>\n\u2b50\u2b50\u2b50 \u4e2d\u7b49<\/td>\n\u2b50\u2b50\u2b50\u2b50 \u8f83\u96be<\/td>\n\u2b50\u2b50 \u7b80\u5355<\/td>\n<\/tr>\n
                                                            \u6027\u80fd<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n<\/tr>\n
                                                            \u9002\u7528\u573a\u666f<\/td>\n\u5927\u5bf9\u8c61\u590d\u7528<\/td>\nCMS\/ParNew<\/td>\n\u5927\u5185\u5b58\u670d\u52a1<\/td>\n\u4e1a\u52a1\u53ef\u62c6\u5206<\/td>\nIO\/\u7f51\u7edc<\/td>\n\u5185\u5b58\u654f\u611f\u7f13\u5b58<\/td>\n<\/tr>\n
                                                            \u63a8\u8350\u6307\u6570<\/td>\n\u2b50\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50<\/td>\n\u2b50\u2b50\u2b50\u2b50<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                                                            \u9009\u578b\u51b3\u7b56\u6811：<\/p>\n

                                                            \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                            \n \u2502 GC\u5f00\u9500\u8d85\u9650 \u2502
                                                            \n \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                                            \n \u2193
                                                            \n \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                            \n \u2502 \u2502
                                                            \n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                            \n\u2502 \u5bf9\u8c61\u662f\u5426 \u2502 \u662f \u2502 \u5185\u5b58\u662f\u5426 \u2502
                                                            \n\u2502 \u53ef\u590d\u7528？ \u2502 \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2192 \u2502 \u654f\u611f\u578b？ \u2502
                                                            \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                                            \n \u2502 \u5426 \u2502 \u662f
                                                            \n \u2193 \u2193
                                                            \n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                            \n\u2502 \u65b9\u68481: \u2502 \u2502 \u65b9\u68486: \u2502
                                                            \n\u2502 \u5bf9\u8c61\u6c60\u5316 \u2502 \u2502 \u8f6f\u5f15\u7528 \u2502
                                                            \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                                            \n \u2502 \u2502
                                                            \n \u2193 \u2193
                                                            \n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                            \n\u2502 \u80fd\u5426\u8c03\u6574 \u2502 \u662f \u2502 \u662f\u5426IO\u5bc6\u96c6\u578b \u2502
                                                            \n\u2502 GC\u53c2\u6570？ \u2502 \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2192 \u2502 \u573a\u666f？ \u2502
                                                            \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
                                                            \n \u2502 \u5426 \u2502 \u662f
                                                            \n \u2193 \u2193
                                                            \n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
                                                            \n\u2502 \u65b9\u68482\/3: \u2502 \u2502 \u65b9\u68485: \u2502
                                                            \n\u2502 \u9608\u503c\/\u6536\u96c6\u5668 \u2502 \u2502 \u76f4\u63a5\u5185\u5b58 \u2502
                                                            \n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/p>\n

                                                            \n

                                                            6.6 \u9884\u9632\u63aa\u65bd\u4e0e\u76d1\u63a7<\/h4>\n

                                                            \/**
                                                            \n * GC\u5f00\u9500\u76d1\u63a7\u9884\u8b66
                                                            \n *\/<\/span>
                                                            \npublic<\/span> class<\/span> GCOverheadGuard<\/span> {<\/span><\/p>\n

                                                            private<\/span> static<\/span> final<\/span> double<\/span> WARNING_GC_RATIO =<\/span> 0.8<\/span>;<\/span> \/\/ 80%\u544a\u8b66<\/span>
                                                            \n private<\/span> static<\/span> final<\/span> double<\/span> CRITICAL_GC_RATIO =<\/span> 0.95<\/span>;<\/span> \/\/ 95%\u4e25\u91cd<\/span><\/p>\n

                                                            \/**
                                                            \n * \u542f\u52a8GC\u76d1\u63a7
                                                            \n *\/<\/span>
                                                            \n public<\/span> static<\/span> void<\/span> startGCMonitor<\/span>(<\/span>)<\/span> {<\/span>
                                                            \n List<\/span><<\/span>java.<\/span>lang.<\/span>management.<\/span><\/span>GarbageCollectorMXBean<\/span>><\/span><\/span> gcBeans =<\/span>
                                                            \n ManagementFactory<\/span>.<\/span>getGarbageCollectorMXBeans<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                            long<\/span> lastGcCount =<\/span> 0<\/span>;<\/span>
                                                            \n long<\/span> lastGcTime =<\/span> 0<\/span>;<\/span>
                                                            \n long<\/span> lastTimestamp =<\/span> System<\/span>.<\/span>currentTimeMillis<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                            while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                                            \n try<\/span> {<\/span>
                                                            \n Thread<\/span>.<\/span>sleep<\/span>(<\/span>5000<\/span>)<\/span>;<\/span> \/\/ \u6bcf5\u79d2\u68c0\u67e5<\/span><\/p>\n

                                                            long<\/span> totalGcCount =<\/span> 0<\/span>;<\/span>
                                                            \n long<\/span> totalGcTime =<\/span> 0<\/span>;<\/span><\/p>\n

                                                            for<\/span> (<\/span>java.<\/span>lang.<\/span>management.<\/span><\/span>GarbageCollectorMXBean<\/span> gc :<\/span> gcBeans)<\/span> {<\/span>
                                                            \n totalGcCount +=<\/span> gc.<\/span>getCollectionCount<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n totalGcTime +=<\/span> gc.<\/span>getCollectionTime<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n }<\/span><\/p>\n

                                                            long<\/span> now =<\/span> System<\/span>.<\/span>currentTimeMillis<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n long<\/span> deltaGcCount =<\/span> totalGcCount –<\/span> lastGcCount;<\/span>
                                                            \n long<\/span> deltaGcTime =<\/span> totalGcTime –<\/span> lastGcTime;<\/span>
                                                            \n long<\/span> deltaTime =<\/span> now –<\/span> lastTimestamp;<\/span><\/p>\n

                                                            if<\/span> (<\/span>deltaGcCount ><\/span> 0<\/span> &&<\/span> deltaTime ><\/span> 0<\/span>)<\/span> {<\/span>
                                                            \n double<\/span> gcRatio =<\/span> (<\/span>double<\/span>)<\/span> deltaGcTime \/<\/span> deltaTime;<\/span><\/p>\n

                                                            if<\/span> (<\/span>gcRatio >=<\/span> CRITICAL_GC_RATIO)<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>err.<\/span>printf<\/span>(<\/span>"[CRITICAL] GC\u8017\u65f6\u5360\u6bd4: %.1f%%，\u5373\u5c06OOM!%n"<\/span>,<\/span>
                                                            \n gcRatio *<\/span> 100<\/span>)<\/span>;<\/span>
                                                            \n \/\/ \u89e6\u53d1\u5806\u8f6c\u50a8<\/span>
                                                            \n triggerHeapDump<\/span>(<\/span>)<\/span>;<\/span>
                                                            \n }<\/span> else<\/span> if<\/span> (<\/span>gcRatio >=<\/span> WARNING_GC_RATIO)<\/span> {<\/span>
                                                            \n System<\/span>.<\/span>err.<\/span>printf<\/span>(<\/span>"[WARNING] GC\u8017\u65f6\u5360\u6bd4: %.1f%%，\u6027\u80fd\u4e25\u91cd\u4e0b\u964d%n"<\/span>,<\/span>
                                                            \n gcRatio *<\/span> 100<\/span>)<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span><\/p>\n

                                                            lastGcCount =<\/span> totalGcCount;<\/span>
                                                            \n lastGcTime =<\/span> totalGcTime;<\/span>
                                                            \n lastTimestamp =<\/span> now;<\/span><\/p>\n

                                                            }<\/span> catch<\/span> (<\/span>InterruptedException<\/span> e)<\/span> {<\/span>
                                                            \n break<\/span>;<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span>
                                                            \n }<\/span><\/p>\n

                                                            private<\/span> static<\/span> void<\/span> triggerHeapDump<\/span>(<\/span>)<\/span> {<\/span>
                                                            \n \/\/ \u5b9e\u73b0\u5806\u8f6c\u50a8\u903b\u8f91<\/span>
                                                            \n }<\/span>
                                                            \n}<\/span><\/p>\n

                                                            \u751f\u4ea7\u73af\u5883JVM\u53c2\u6570\u63a8\u8350：<\/p>\n

                                                            # \u57fa\u7840\u914d\u7f6e<\/span>
                                                            \n-Xms4g -Xmx4g
                                                            \n-XX:+AlwaysPreTouch # \u542f\u52a8\u65f6\u9884\u5206\u914d\u5185\u5b58<\/span><\/p>\n

                                                            # GC\u5f00\u9500\u8d85\u9650\u4fdd\u62a4<\/span>
                                                            \n-XX:-UseGCOverheadLimit # \u7981\u7528GC\u5f00\u9500\u9650\u5236（\u8c28\u614e）<\/span>
                                                            \n-XX:GCTimeLimit=<\/span>98<\/span> # GC\u65f6\u95f4\u4e0a\u9650<\/span>
                                                            \n-XX:GCHeapFreeLimit=<\/span>2<\/span> # GC\u540e\u7a7a\u95f2\u7a7a\u95f4\u4e0b\u9650<\/span><\/p>\n

                                                            # \u65e5\u5fd7\u76d1\u63a7<\/span>
                                                            \n-XX:+PrintGCApplicationConcurrentTime
                                                            \n-XX:+PrintGCApplicationStoppedTime
                                                            \n-XX:+PrintSafepointStatistics
                                                            \n-XX:PrintSafepointStatisticsCount=<\/span>1<\/span><\/p>\n

                                                            # OOM\u5904\u7406<\/span>
                                                            \n-XX:+HeapDumpOnOutOfMemoryError
                                                            \n-XX:HeapDumpPath=<\/span>\/var\/log\/jvm\/dumps\/
                                                            \n-XX:OnOutOfMemoryError=<\/span>"kill -3 %p; kill -9 %p"<\/span><\/p>\n

                                                            \n

                                                            6.7 \u9762\u8bd5\u9ad8\u9891\u9898<\/h4>\n

                                                            Q1：GC overhead limit exceeded \u548c Java heap space \u6709\u4ec0\u4e48\u533a\u522b？<\/p>\n\n\u7ef4\u5ea6GC overhead limitJava heap space<\/tr>\n\n\n\n\n\n
                                                            \u89e6\u53d1\u6761\u4ef6<\/td>\nGC\u8017\u65f6＞98%，\u56de\u6536＜2%<\/td>\n\u5806\u5185\u5b58\u5b8c\u5168\u8017\u5c3d<\/td>\n<\/tr>\n
                                                            \u524d\u5146<\/td>\n\u9891\u7e41Full GC，\u56de\u6536\u6781\u5c11<\/td>\nAllocation Failure<\/td>\n<\/tr>\n
                                                            \u6062\u590d\u53ef\u80fd<\/td>\n\u6709（\u589e\u52a0\u5806\/\u4f18\u5316GC）<\/td>\n\u65e0（\u5fc5\u987bdump\u5206\u6790）<\/td>\n<\/tr>\n
                                                            \u5371\u5bb3\u7a0b\u5ea6<\/td>\n\u6027\u80fd\u4e25\u91cd\u4e0b\u964d<\/td>\n\u670d\u52a1\u4e0d\u53ef\u7528<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                                                            Q2：\u5927\u5bf9\u8c61\u76f4\u63a5\u8fdb\u5165\u8001\u5e74\u4ee3\u7684\u6761\u4ef6？<\/p>\n

                                                              \n
                                                            • CMS\/ParNew: -XX:PretenureSizeThreshold=3m<\/li>\n
                                                            • G1: \u5bf9\u8c61\u5927\u5c0f > G1HeapRegionSize\/2 (\u9ed8\u8ba41MB)<\/li>\n
                                                            • Parallel: \u65e0\u6b64\u53c2\u6570，\u901a\u8fc7TLAB\u5206\u914d<\/li>\n<\/ul>\n

                                                              Q3：\u5982\u4f55\u5224\u65ad\u662fGC\u5f00\u9500\u8d85\u9650\u8fd8\u662f\u5185\u5b58\u6cc4\u6f0f？<\/p>\n

                                                              # \u89c2\u5bdfGC\u540e\u5185\u5b58\u8d8b\u52bf<\/span>
                                                              \njstat -gcutil <<\/span>pid><\/span> 1000<\/span> 10<\/span><\/p>\n

                                                              S0 S1 E O M CCS YGC YGCT FGC FGCT GCT
                                                              \n 0.00<\/span> 0.00<\/span> 2.45<\/span> 98.00<\/span> 95.00<\/span> 90.00<\/span> 15<\/span> 0.324<\/span> 25<\/span> 45.234<\/span> 45.558<\/span>
                                                              \n# FGC=25, FGCT=45s \u2192 25\u6b21Full GC，\u603b\u8017\u65f645\u79d2<\/span>
                                                              \n# O\u533a98% \u2192 \u6bcf\u6b21\u56de\u6536\u6781\u5c11 \u2192 GC\u5f00\u9500\u8d85\u9650<\/span><\/p>\n

                                                              Q4：\u5927\u5bf9\u8c61\u6c60\u548c\u76f4\u63a5\u5185\u5b58\u5982\u4f55\u9009\u62e9？<\/p>\n

                                                                \n
                                                              • \u5bf9\u8c61\u6c60：CPU\u5bc6\u96c6\u578b，\u9891\u7e41\u8bfb\u5199，\u5185\u5b58\u53ef\u63a7<\/li>\n
                                                              • \u76f4\u63a5\u5185\u5b58：IO\u5bc6\u96c6\u578b，\u96f6\u62f7\u8d1d\u9700\u6c42，\u5185\u5b58\u5145\u8db3<\/li>\n
                                                              • \u6df7\u5408：\u6c60\u5316\u76f4\u63a5\u5185\u5b58（Netty ByteBuf）<\/li>\n<\/ul>\n

                                                                Q5：\u4ec0\u4e48\u60c5\u51b5\u4e0d\u9002\u5408\u5bf9\u8c61\u6c60？<\/p>\n

                                                              • \u5bf9\u8c61\u521b\u5efa\u5f00\u9500\u5c0f<\/li>\n
                                                              • \u5bf9\u8c61\u72b6\u6001\u590d\u6742，\u91cd\u7f6e\u6210\u672c\u9ad8<\/li>\n
                                                              • \u5185\u5b58\u975e\u5e38\u5145\u8db3，GC\u538b\u529b\u5c0f<\/li>\n
                                                              • \u5bf9\u8c61\u4f7f\u7528\u65f6\u95f4\u77ed，\u6c60\u5316\u53cd\u800c\u589e\u52a0\u590d\u6742\u5ea6<\/li>\n
                                                                \n

                                                                \u4e03\u3001\u5b9e\u6218\u516d：\u7ebf\u7a0b\u521b\u5efa\u5931\u8d25 \u2014\u2014 \u7ebf\u7a0b\u6cc4\u6f0f<\/h3>\n

                                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                                7.1 \u590d\u73b0\u4ee3\u7801<\/h4>\n

                                                                package<\/span> tech.<\/span>oom.<\/span>demo.<\/span>thread<\/span>;<\/span><\/p>\n

                                                                import<\/span> java.<\/span>util.<\/span>concurrent.<\/span><\/span>CountDownLatch<\/span>;<\/span><\/p>\n

                                                                \/**
                                                                \n * \u573a\u666f：\u65e0\u9650\u521b\u5efa\u7ebf\u7a0b\u4e14\u6c38\u4e0d\u9000\u51fa
                                                                \n * \u76d1\u63a7\u547d\u4ee4：top -H -p <pid>
                                                                \n *\/<\/span>
                                                                \npublic<\/span> class<\/span> ThreadOOMDemo<\/span> {<\/span>
                                                                \n private<\/span> static<\/span> final<\/span> CountDownLatch<\/span> LATCH =<\/span> new<\/span> CountDownLatch<\/span>(<\/span>1<\/span>)<\/span>;<\/span>
                                                                \n private<\/span> static<\/span> int<\/span> threadCount =<\/span> 0<\/span>;<\/span><\/p>\n

                                                                public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== \u7ebf\u7a0b\u6cc4\u6f0f\u6a21\u62df ==="<\/span>)<\/span>;<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u7cfb\u7edf\u7ebf\u7a0b\u9650\u5236: ulimit -u"<\/span>)<\/span>;<\/span><\/p>\n

                                                                try<\/span> {<\/span>
                                                                \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                                                \n Thread<\/span> thread =<\/span> new<\/span> Thread<\/span>(<\/span>(<\/span>)<\/span> -><\/span> {<\/span>
                                                                \n try<\/span> {<\/span>
                                                                \n LATCH.<\/span>await<\/span>(<\/span>)<\/span>;<\/span> \/\/ \u6c38\u4e45\u963b\u585e<\/span>
                                                                \n }<\/span> catch<\/span> (<\/span>InterruptedException<\/span> e)<\/span> {<\/span>
                                                                \n Thread<\/span>.<\/span>currentThread<\/span>(<\/span>)<\/span>.<\/span>interrupt<\/span>(<\/span>)<\/span>;<\/span>
                                                                \n }<\/span>
                                                                \n }<\/span>,<\/span> "leak-thread-"<\/span> +<\/span> threadCount)<\/span>;<\/span><\/p>\n

                                                                thread.<\/span>start<\/span>(<\/span>)<\/span>;<\/span>
                                                                \n threadCount++<\/span>;<\/span><\/p>\n

                                                                if<\/span> (<\/span>threadCount %<\/span> 500<\/span> ==<\/span> 0<\/span>)<\/span> {<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5df2\u521b\u5efa: %d \u4e2a\u7ebf\u7a0b%n"<\/span>,<\/span> threadCount)<\/span>;<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5f53\u524d\u6d3b\u8dc3\u7ebf\u7a0b: %d%n"<\/span>,<\/span>
                                                                \n Thread<\/span>.<\/span>activeCount<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                                \n }<\/span>
                                                                \n }<\/span>
                                                                \n }<\/span> catch<\/span> (<\/span>OutOfMemoryError<\/span> e)<\/span> {<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\\\\n========== \u7ebf\u7a0b\u521b\u5efa\u5931\u8d25 =========="<\/span>)<\/span>;<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u6700\u7ec8\u7ebf\u7a0b\u6570: %d%n"<\/span>,<\/span> threadCount)<\/span>;<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                                \n }<\/span>
                                                                \n }<\/span>
                                                                \n}<\/span><\/p>\n

                                                                7.2 \u89e3\u51b3\u65b9\u6848\u4e0e\u4ee3\u7801\u4fee\u590d<\/h4>\n

                                                                \u2705 \u65b9\u68481：\u7ebf\u7a0b\u6c60<\/h5>\n

                                                                public<\/span> class<\/span> ThreadOOM_Fix1_ThreadPool<\/span> {<\/span>
                                                                \n private<\/span> static<\/span> final<\/span> ThreadPoolExecutor<\/span> POOL =<\/span>
                                                                \n new<\/span> ThreadPoolExecutor<\/span>(<\/span>
                                                                \n 10<\/span>,<\/span> \/\/ corePoolSize<\/span>
                                                                \n 50<\/span>,<\/span> \/\/ maximumPoolSize<\/span>
                                                                \n 60L<\/span>,<\/span> TimeUnit<\/span>.<\/span>SECONDS,<\/span> \/\/ keepAliveTime<\/span>
                                                                \n new<\/span> LinkedBlockingQueue<\/span><<\/span>><\/span><\/span>(<\/span>1000<\/span>)<\/span>,<\/span> \/\/ workQueue<\/span>
                                                                \n new<\/span> ThreadPoolExecutor.<\/span>CallerRunsPolicy<\/span>(<\/span>)<\/span> \/\/ \u62d2\u7edd\u7b56\u7565<\/span>
                                                                \n )<\/span>;<\/span><\/p>\n

                                                                static<\/span> {<\/span>
                                                                \n POOL.<\/span>allowCoreThreadTimeOut<\/span>(<\/span>true<\/span>)<\/span>;<\/span> \/\/ \u6838\u5fc3\u7ebf\u7a0b\u4e5f\u8d85\u65f6<\/span>
                                                                \n }<\/span><\/p>\n

                                                                public<\/span> static<\/span> void<\/span> submitTask<\/span>(<\/span>Runnable<\/span> task)<\/span> {<\/span>
                                                                \n POOL.<\/span>submit<\/span>(<\/span>task)<\/span>;<\/span>
                                                                \n }<\/span>
                                                                \n}<\/span><\/p>\n

                                                                \u2705 \u65b9\u68482：\u51cf\u5c0f\u6808\u5927\u5c0f<\/h5>\n

                                                                # \u8c03\u5c0f-Xss，\u589e\u52a0\u53ef\u521b\u5efa\u7ebf\u7a0b\u6570<\/span>
                                                                \njava -Xss256k ThreadOOMDemo<\/p>\n

                                                                \n

                                                                \u516b\u3001\u5b9e\u6218\u4e03：\u4ea4\u6362\u7a7a\u95f4\u8017\u5c3d \u2014\u2014 \u7cfb\u7edf\u7ea7\u5185\u5b58\u6cc4\u6f0f<\/h3>\n

                                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                                8.1 \u590d\u73b0\u4ee3\u7801<\/h4>\n

                                                                package<\/span> tech.<\/span>oom.<\/span>demo.<\/span>swap<\/span>;<\/span><\/p>\n

                                                                import<\/span> java.<\/span>util.<\/span><\/span>ArrayList<\/span>;<\/span>
                                                                \nimport<\/span> java.<\/span>util.<\/span><\/span>List<\/span>;<\/span><\/p>\n

                                                                \/**
                                                                \n * \u573a\u666f：\u6301\u7eed\u6301\u6709\u5927\u5bf9\u8c61，\u8017\u5c3d\u7269\u7406\u5185\u5b58+\u4ea4\u6362\u7a7a\u95f4
                                                                \n * \u76d1\u63a7\u547d\u4ee4：free -h; vmstat 1
                                                                \n *\/<\/span>
                                                                \npublic<\/span> class<\/span> SwapSpaceOOMDemo<\/span> {<\/span>
                                                                \n private<\/span> static<\/span> final<\/span> List<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> MEMORY_HOG =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                                public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> InterruptedException<\/span> {<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"=== \u4ea4\u6362\u7a7a\u95f4\u8017\u5c3d\u6a21\u62df ==="<\/span>)<\/span>;<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\u8bf7\u4f7f\u7528 free -h \u76d1\u63a7\u7cfb\u7edf\u5185\u5b58"<\/span>)<\/span>;<\/span><\/p>\n

                                                                int<\/span> count =<\/span> 0<\/span>;<\/span>
                                                                \n try<\/span> {<\/span>
                                                                \n while<\/span> (<\/span>true<\/span>)<\/span> {<\/span>
                                                                \n \/\/ \u6bcf\u6b21\u5206\u914d100MB<\/span>
                                                                \n MEMORY_HOG.<\/span>add<\/span>(<\/span>new<\/span> byte<\/span>[<\/span>100<\/span> *<\/span> 1024<\/span> *<\/span> 1024<\/span>]<\/span>)<\/span>;<\/span>
                                                                \n count++<\/span>;<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>printf<\/span>(<\/span>"\u5df2\u5206\u914d: %d00 MB%n"<\/span>,<\/span> count)<\/span>;<\/span>
                                                                \n Thread<\/span>.<\/span>sleep<\/span>(<\/span>500<\/span>)<\/span>;<\/span>
                                                                \n }<\/span>
                                                                \n }<\/span> catch<\/span> (<\/span>OutOfMemoryError<\/span> e)<\/span> {<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>"\\\\n========== \u7cfb\u7edf\u5185\u5b58\u8017\u5c3d =========="<\/span>)<\/span>;<\/span>
                                                                \n System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
                                                                \n }<\/span>
                                                                \n }<\/span>
                                                                \n}<\/span><\/p>\n

                                                                8.2 \u89e3\u51b3\u65b9\u6848（\u7cfb\u7edf\u7ea7）<\/h4>\n

                                                                \u2705 \u6269\u5bb9\u4ea4\u6362\u7a7a\u95f4<\/h5>\n

                                                                # Linux \u589e\u52a02GB\u4ea4\u6362\u6587\u4ef6<\/span>
                                                                \nsudo<\/span> fallocate -l 2G \/swapfile
                                                                \nsudo<\/span> chmod<\/span> 600<\/span> \/swapfile
                                                                \nsudo<\/span> mkswap<\/span> \/swapfile
                                                                \nsudo<\/span> swapon<\/span> \/swapfile<\/p>\n

                                                                # \u6c38\u4e45\u751f\u6548（\/etc\/fstab）<\/span>
                                                                \necho<\/span> '\/swapfile none swap sw 0 0'<\/span> |<\/span> sudo<\/span> tee<\/span> -a \/etc\/fstab<\/p>\n

                                                                \u2705 Docker\u5bb9\u5668\u5185\u5b58\u9650\u5236<\/h5>\n

                                                                docker<\/span> run -m 4g –memory-swap 8g java-app<\/p>\n

                                                                \n

                                                                \u4e5d\u3001\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5（\u53ef\u76f4\u63a5\u843d\u5730）<\/h3>\n

                                                                10.1 \u4ee3\u7801\u89c4\u8303（\u5f3a\u5236）<\/h4>\n

                                                                \/\/ \u2705 \u9759\u6001\u96c6\u5408\u5fc5\u987b\u52a0\u5bb9\u91cf\u9650\u5236<\/span>
                                                                \nprivate<\/span> static<\/span> final<\/span> Cache<\/span><<\/span>String<\/span>,<\/span> Data<\/span>><\/span><\/span> CACHE =<\/span>
                                                                \n Caffeine<\/span>.<\/span>newBuilder<\/span>(<\/span>)<\/span>.<\/span>maximumSize<\/span>(<\/span>1000<\/span>)<\/span>.<\/span>build<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                                \/\/ \u2705 ThreadLocal\u5fc5\u987bremove<\/span>
                                                                \nThreadLocal<\/span><<\/span>Session<\/span>><\/span><\/span> TL =<\/span> new<\/span> ThreadLocal<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>
                                                                \ntry<\/span> {<\/span>
                                                                \n TL.<\/span>set<\/span>(<\/span>session)<\/span>;<\/span>
                                                                \n \/\/ \u4e1a\u52a1\u903b\u8f91<\/span>
                                                                \n}<\/span> finally<\/span> {<\/span>
                                                                \n TL.<\/span>remove<\/span>(<\/span>)<\/span>;<\/span> \/\/ \u52a1\u5fc5\u6267\u884c<\/span>
                                                                \n}<\/span><\/p>\n

                                                                \/\/ \u2705 \u5927\u5bf9\u8c61\u4f7f\u7528\u5bf9\u8c61\u6c60<\/span>
                                                                \nObjectPool<\/span><<\/span>byte<\/span>[<\/span>]<\/span>><\/span> pool =<\/span> new<\/span> GenericObjectPool<\/span><<\/span>><\/span><\/span>(<\/span>new<\/span> PooledObjectFactory<\/span>(<\/span>)<\/span>)<\/span>;<\/span><\/p>\n

                                                                \/\/ \u2705 \u52a8\u6001\u4ee3\u7406\u5fc5\u987b\u7f13\u5b58<\/span>
                                                                \nprivate<\/span> static<\/span> final<\/span> Map<\/span><<\/span>Class<\/span><<\/span>?<\/span>><\/span>,<\/span> Class<\/span><<\/span>?<\/span>><\/span>><\/span><\/span> PROXY_CACHE =<\/span> new<\/span> ConcurrentHashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span><\/p>\n

                                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                                10.2 JVM\u53c2\u6570\u6a21\u677f（\u751f\u4ea7）<\/h4>\n

                                                                # \u5185\u5b58\u8bbe\u7f6e<\/span>
                                                                \n-Xms4g -Xmx4g -Xmn1.5g
                                                                \n-XX:MetaspaceSize=<\/span>256m -XX:MaxMetaspaceSize=<\/span>512m
                                                                \n-XX:MaxDirectMemorySize=<\/span>256m<\/p>\n

                                                                # GC\u9009\u62e9（JDK8）<\/span>
                                                                \n-XX:+UseG1GC -XX:MaxGCPauseMillis=<\/span>200<\/span>
                                                                \n-XX:G1HeapRegionSize=<\/span>8m
                                                                \n-XX:InitiatingHeapOccupancyPercent=<\/span>45<\/span><\/p>\n

                                                                # \u8bca\u65ad\u53c2\u6570（\u5fc5\u5f00）<\/span>
                                                                \n-XX:+HeapDumpOnOutOfMemoryError
                                                                \n-XX:HeapDumpPath=<\/span>\/data\/logs\/dump-$(<\/span>date<\/span>)<\/span><\/span>.hprof
                                                                \n-XX:+PrintGCDetails -XX:+PrintGCDateStamps
                                                                \n-Xloggc:\/data\/logs\/gc-$(<\/span>date<\/span>)<\/span><\/span>.log<\/p>\n

                                                                # \u5e94\u6025\u4f18\u5316<\/span>
                                                                \n-XX:+DisableExplicitGC # \u7981\u6b62System.gc()<\/span>
                                                                \n-XX:+ExitOnOutOfMemoryError # OOM\u65f6\u7acb\u5373\u9000\u51fa<\/span><\/p>\n

                                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                                10.3 \u76d1\u63a7\u544a\u8b66\u914d\u7f6e<\/h4>\n

                                                                # Prometheus \u544a\u8b66\u89c4\u5219<\/span>
                                                                \ngroups<\/span>:<\/span>
                                                                \n–<\/span> name<\/span>:<\/span> jvm_oom_alerts
                                                                \n rules<\/span>:<\/span>
                                                                \n –<\/span> alert<\/span>:<\/span> \u8001\u5e74\u4ee3\u4f7f\u7528\u7387\u8fc7\u9ad8
                                                                \n expr<\/span>:<\/span> jvm_memory_used_bytes{<\/span>area="heap",<\/span>id="G1 Old Gen"}<\/span> \/ jvm_memory_max_bytes{<\/span>area="heap"}<\/span> ><\/span> 0.85
                                                                \n for<\/span>:<\/span> 10m
                                                                \n annotations<\/span>:<\/span>
                                                                \n summary<\/span>:<\/span> "\u5e94\u7528 {{ $labels.instance }} \u8001\u5e74\u4ee3\u4f7f\u7528\u7387 > 85%"<\/span><\/p>\n

                                                                –<\/span> alert<\/span>:<\/span> Full GC \u8fc7\u4e8e\u9891\u7e41
                                                                \n expr<\/span>:<\/span> rate(jvm_gc_collection_seconds_count{<\/span>gc="G1 Old Generation"}<\/span>[<\/span>10m]<\/span>) ><\/span> 0.1
                                                                \n for<\/span>:<\/span> 5m
                                                                \n annotations<\/span>:<\/span>
                                                                \n summary<\/span>:<\/span> "\u5e94\u7528 {{ $labels.instance }} Full GC \u9891\u7387 > 6\u6b21\/\u5206\u949f"<\/span><\/p>\n

                                                                –<\/span> alert<\/span>:<\/span> \u5143\u7a7a\u95f4\u6301\u7eed\u589e\u957f
                                                                \n expr<\/span>:<\/span> predict_linear(jvm_memory_used_bytes{<\/span>area="nonheap",<\/span>id="Metaspace"}<\/span>[<\/span>1h]<\/span>,<\/span> 3600) ><\/span> jvm_memory_max_bytes
                                                                \n for<\/span>:<\/span> 30m
                                                                \n annotations<\/span>:<\/span>
                                                                \n summary<\/span>:<\/span> "\u5143\u7a7a\u95f41\u5c0f\u65f6\u5185\u53ef\u80fd\u8017\u5c3d"<\/span><\/p>\n

                                                                \n

                                                                \u5341\u3001\u603b\u7ed3：\u4ece\u201c\u9047\u5230OOM\u614c\u201d\u5230\u201c\u671f\u5f85OOM\u201d<\/h3>\n

                                                                11.1 7\u79cdOOM\u901f\u67e5\u8868<\/h4>\n\nOOM\u7c7b\u578b\u65e5\u5fd7\u5173\u952e\u5b57\u6838\u5fc3\u5224\u65ad3\u5206\u949f\u5b9a\u4f4d1\u5c0f\u65f6\u4fee\u590d<\/tr>\n\n\n\n\n\n\n\n\n
                                                                \u5806\u5185\u5b58\u6cc4\u6f0f<\/td>\nJava heap space<\/td>\n\u8001\u5e74\u4ee3\u6301\u7eed\u2191<\/td>\nMAT\u2192\u9759\u6001\u96c6\u5408<\/td>\n\u7f13\u5b58\u52a0\u4e0a\u9650<\/td>\n<\/tr>\n
                                                                \u6808\u6ea2\u51fa<\/td>\nStackOverflowError<\/td>\n\u540c\u4e00\u884c\u9012\u5f52<\/td>\n\u5f02\u5e38\u6808<\/td>\n\u9012\u5f52\u6539\u8fed\u4ee3<\/td>\n<\/tr>\n
                                                                \u5143\u7a7a\u95f4\u6ea2\u51fa<\/td>\nMetaspace<\/td>\n\u7c7b\u52a0\u8f7d\u6570\u2191<\/td>\njstat -class<\/td>\n\u7f13\u5b58\u4ee3\u7406\u7c7b<\/td>\n<\/tr>\n
                                                                \u76f4\u63a5\u5185\u5b58<\/td>\nDirect buffer memory<\/td>\n\u5806\u5185\u5b58\u4f4e，RES\u9ad8<\/td>\nNIO\u4f7f\u7528\u5904<\/td>\n\u663e\u5f0fclean()<\/td>\n<\/tr>\n
                                                                GC\u5f00\u9500\u8d85\u9650<\/td>\nGC overhead limit<\/td>\nFull GC\u6781\u9891\u7e41<\/td>\nGC\u65e5\u5fd7<\/td>\n\u5bf9\u8c61\u6c60\u590d\u7528<\/td>\n<\/tr>\n
                                                                \u7ebf\u7a0b\u6cc4\u6f0f<\/td>\nunable to create thread<\/td>\n\u7ebf\u7a0b\u6570\u2191<\/td>\ntop -H -p<\/td>\n\u7ebf\u7a0b\u6c60<\/td>\n<\/tr>\n
                                                                \u4ea4\u6362\u7a7a\u95f4<\/td>\nOut of swap space<\/td>\nfree -h\u663e\u793aswap\u6ee1<\/td>\n\u7cfb\u7edf\u76d1\u63a7<\/td>\n\u6269\u5bb9\/\u964d\u5185\u5b58<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                                11.2 \u94c1\u5f8b\u5341\u6761<\/h4>\n
                                                              • \u9759\u6001\u96c6\u5408\u5fc5\u987b\u52a0\u5bb9\u91cf\u4e0a\u9650 \u2014\u2014 90%\u5806\u6cc4\u6f0f\u6e90\u4e8e\u6b64<\/li>\n
                                                              • ThreadLocal\u5fc5\u987bremove \u2014\u2014 \u7ebf\u7a0b\u6c60\u590d\u7528\u5fc5\u6e05\u7406<\/li>\n
                                                              • \u5927\u5bf9\u8c61\u5fc5\u987b\u6c60\u5316 \u2014\u2014 2MB\u4ee5\u4e0a\u8003\u8651\u590d\u7528<\/li>\n
                                                              • \u52a8\u6001\u4ee3\u7406\u5fc5\u987b\u7f13\u5b58 \u2014\u2014 \u540c\u7c7b\u578b\u53ea\u751f\u6210\u4e00\u6b21<\/li>\n
                                                              • \u7ebf\u7a0b\u5fc5\u987b\u7528\u7ebf\u7a0b\u6c60 \u2014\u2014 \u7981\u6b62new Thread()<\/li>\n
                                                              • \u76f4\u63a5\u5185\u5b58\u5fc5\u987b\u91ca\u653e \u2014\u2014 \u7528\u5b8c\u7acb\u5373clean()<\/li>\n
                                                              • \u9012\u5f52\u5fc5\u987b\u52a0\u7ec8\u6b62\u6761\u4ef6 \u2014\u2014 \u6700\u597d\u6539\u6210\u8fed\u4ee3<\/li>\n
                                                              • JVM\u53c2\u6570\u5fc5\u914ddump \u2014\u2014 OOM\u65f6\u7559\u8bc1\u636e<\/li>\n
                                                              • \u5185\u5b58\u5fc5\u987b\u76d1\u63a7 \u2014\u2014 \u8001\u5e74\u4ee3\/\u5143\u7a7a\u95f4\u66f2\u7ebf<\/li>\n
                                                              • \u538b\u6d4b\u5fc5\u8dd1 \u2014\u2014 \u4e0a\u7ebf\u524d48\u5c0f\u65f6\u7a33\u5b9a\u6027\u9a8c\u8bc1<\/li>\n

                                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                                11.3 \u5199\u5728\u6700\u540e<\/h4>\n

                                                                OOM\u4e0d\u662f\u7a0b\u5e8f\u7684\u7ec8\u70b9，\u800c\u662f\u67b6\u6784\u4f18\u5316\u7684\u8d77\u70b9\u3002<\/p>\n

                                                                \u5f53\u4f60\u9047\u5230OOM\u65f6：<\/p>\n

                                                              • \u4e0d\u8981\u614c \u2014\u2014 \u8fd9\u662fJVM\u5728\u4fdd\u62a4\u4f60<\/li>\n
                                                              • \u7559\u8bc1\u636e \u2014\u2014 \u5806\u8f6c\u50a8\u662f\u7834\u6848\u5173\u952e<\/li>\n
                                                              • \u770b\u8d8b\u52bf \u2014\u2014 \u76d1\u63a7\u66f2\u7ebf\u63ed\u793a\u771f\u76f8<\/li>\n
                                                              • \u590d\u73b0\u573a\u666f \u2014\u2014 \u80fd\u590d\u73b0\u5c31\u80fd\u89e3\u51b3<\/li>\n
                                                              • \u89e6\u7c7b\u65c1\u901a \u2014\u2014 \u4fee\u590d\u4e00\u4e2a，\u9884\u9632\u4e00\u7c7b<\/li>\n

                                                                \u771f\u6b63\u7684\u4e13\u5bb6，\u4e0d\u662f\u4ece\u4e0d\u5199\u51faOOM\u7684\u4ee3\u7801，\u800c\u662f\u80fd\u5728OOM\u53d1\u751f\u540e，30\u5206\u949f\u5185\u627e\u5230\u6839\u56e0\u5e76\u4fee\u590d\u3002<\/p>\n

                                                                \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

                                                                \u4e92\u52a8\u8bdd\u9898： \u4f60\u5728\u751f\u4ea7\u73af\u5883\u4e2d\u8fd8\u9047\u5230\u8fc7\u54ea\u4e9b\u201c\u5947\u8469\u201d\u7684OOM？\u662fJDK bug，\u8fd8\u662f\u6846\u67b6\u5751，\u8fd8\u662f\u81ea\u5df1\u6316\u7684\u5751？\u6b22\u8fce\u5728\u8bc4\u8bba\u533a\u5206\u4eab\u4f60\u7684\u201c\u6392\u96f7\u201d\u4f20\u5947！<\/p>\n","protected":false},"excerpt":{"rendered":"

                                                                OOM \u5b9e\u6218\u5168\u89e3：7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5（\u4e0b） \u4f5c\u8005：Weisian \u53d1\u5e03\u65f6\u95f4：2026\u5e742\u670813\u65e5 \u4e00\u3001OOM\u8bca\u65ad\u524d\u7f6e\u51c6\u5907：\u73af\u5883\u4e0e\u5de5\u5177
                                                                \n1.1 \u73af\u5883\u57fa\u7840\u914d\u7f6e
                                                                \n1.1.1 \u8f6f\u786c\u4ef6\u73af\u5883\u8981\u6c42
                                                                \n\u73af\u5883\u9879\u63a8\u8350\u914d\u7f6e\u517c\u5bb9\u6027\u8bf4\u660eJDK\u7248\u672cOracle JDK 8 \/ OpenJDK 11JDK 17\u9700\u5fae\u8c03\u5143\u7a7a\u95f4\u53c2\u6570，\u6838\u5fc3\u903b\u8f91\u901a\u7528IDE\u5de5\u5177IntelliJ IDEA<\/p>\n","protected":false},"author":2,"featured_media":75907,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[8117,8118,8116,8115,426],"topic":[],"class_list":["post-75927","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server","tag-arthas","tag-jconsole","tag-mat","tag-oom","tag-jvm"],"yoast_head":"\nJVM-12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.wsisp.com\/helps\/75927.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"JVM-12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"og:description\" content=\"OOM \u5b9e\u6218\u5168\u89e3：7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5（\u4e0b） \u4f5c\u8005：Weisian \u53d1\u5e03\u65f6\u95f4：2026\u5e742\u670813\u65e5 \u4e00\u3001OOM\u8bca\u65ad\u524d\u7f6e\u51c6\u5907：\u73af\u5883\u4e0e\u5de5\u5177 1.1 \u73af\u5883\u57fa\u7840\u914d\u7f6e 1.1.1 \u8f6f\u786c\u4ef6\u73af\u5883\u8981\u6c42 \u73af\u5883\u9879\u63a8\u8350\u914d\u7f6e\u517c\u5bb9\u6027\u8bf4\u660eJDK\u7248\u672cOracle JDK 8 \/ OpenJDK 11JDK 17\u9700\u5fae\u8c03\u5143\u7a7a\u95f4\u53c2\u6570，\u6838\u5fc3\u903b\u8f91\u901a\u7528IDE\u5de5\u5177IntelliJ IDEA\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.wsisp.com\/helps\/75927.html\" \/>\n<meta property=\"og:site_name\" content=\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"article:published_time\" content=\"2026-02-13T06:26:23+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/02\/20260213062619-698ec40b28e50.png\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u4f5c\u8005\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4\" \/>\n\t<meta name=\"twitter:data2\" content=\"37 \u5206\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/75927.html\",\"url\":\"https:\/\/www.wsisp.com\/helps\/75927.html\",\"name\":\"JVM-12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\",\"isPartOf\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/#website\"},\"datePublished\":\"2026-02-13T06:26:23+00:00\",\"dateModified\":\"2026-02-13T06:26:23+00:00\",\"author\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/75927.html#breadcrumb\"},\"inLanguage\":\"zh-Hans\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.wsisp.com\/helps\/75927.html\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/75927.html#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"\u9996\u9875\",\"item\":\"https:\/\/www.wsisp.com\/helps\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"JVM--12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#website\",\"url\":\"https:\/\/www.wsisp.com\/helps\/\",\"name\":\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\",\"description\":\"\u9999\u6e2f\u670d\u52a1\u5668_\u9999\u6e2f\u4e91\u670d\u52a1\u5668\u8d44\u8baf_\u670d\u52a1\u5668\u5e2e\u52a9\u6587\u6863_\u670d\u52a1\u5668\u6559\u7a0b\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.wsisp.com\/helps\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"zh-Hans\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41\",\"name\":\"admin\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"zh-Hans\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery\",\"contentUrl\":\"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery\",\"caption\":\"admin\"},\"sameAs\":[\"http:\/\/wp.wsisp.com\"],\"url\":\"https:\/\/www.wsisp.com\/helps\/author\/admin\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"JVM-12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.wsisp.com\/helps\/75927.html","og_locale":"zh_CN","og_type":"article","og_title":"JVM-12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","og_description":"OOM \u5b9e\u6218\u5168\u89e3：7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5（\u4e0b） \u4f5c\u8005：Weisian \u53d1\u5e03\u65f6\u95f4：2026\u5e742\u670813\u65e5 \u4e00\u3001OOM\u8bca\u65ad\u524d\u7f6e\u51c6\u5907：\u73af\u5883\u4e0e\u5de5\u5177 1.1 \u73af\u5883\u57fa\u7840\u914d\u7f6e 1.1.1 \u8f6f\u786c\u4ef6\u73af\u5883\u8981\u6c42 \u73af\u5883\u9879\u63a8\u8350\u914d\u7f6e\u517c\u5bb9\u6027\u8bf4\u660eJDK\u7248\u672cOracle JDK 8 \/ OpenJDK 11JDK 17\u9700\u5fae\u8c03\u5143\u7a7a\u95f4\u53c2\u6570，\u6838\u5fc3\u903b\u8f91\u901a\u7528IDE\u5de5\u5177IntelliJ IDEA","og_url":"https:\/\/www.wsisp.com\/helps\/75927.html","og_site_name":"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","article_published_time":"2026-02-13T06:26:23+00:00","og_image":[{"url":"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/02\/20260213062619-698ec40b28e50.png"}],"author":"admin","twitter_card":"summary_large_image","twitter_misc":{"\u4f5c\u8005":"admin","\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4":"37 \u5206"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.wsisp.com\/helps\/75927.html","url":"https:\/\/www.wsisp.com\/helps\/75927.html","name":"JVM-12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","isPartOf":{"@id":"https:\/\/www.wsisp.com\/helps\/#website"},"datePublished":"2026-02-13T06:26:23+00:00","dateModified":"2026-02-13T06:26:23+00:00","author":{"@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41"},"breadcrumb":{"@id":"https:\/\/www.wsisp.com\/helps\/75927.html#breadcrumb"},"inLanguage":"zh-Hans","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.wsisp.com\/helps\/75927.html"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.wsisp.com\/helps\/75927.html#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"\u9996\u9875","item":"https:\/\/www.wsisp.com\/helps"},{"@type":"ListItem","position":2,"name":"JVM--12-OOM\u5b9e\u6218\u5168\u89e3\uff1a7\u79cd\u6ea2\u51fa\u590d\u73b0\u3001MAT\u5b9a\u4f4d\u3001\u4ee3\u7801\u4fee\u590d\u4e0e\u751f\u4ea7\u6700\u4f73\u5b9e\u8df5\uff08\u4e0b\uff09"}]},{"@type":"WebSite","@id":"https:\/\/www.wsisp.com\/helps\/#website","url":"https:\/\/www.wsisp.com\/helps\/","name":"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","description":"\u9999\u6e2f\u670d\u52a1\u5668_\u9999\u6e2f\u4e91\u670d\u52a1\u5668\u8d44\u8baf_\u670d\u52a1\u5668\u5e2e\u52a9\u6587\u6863_\u670d\u52a1\u5668\u6559\u7a0b","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.wsisp.com\/helps\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"zh-Hans"},{"@type":"Person","@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41","name":"admin","image":{"@type":"ImageObject","inLanguage":"zh-Hans","@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/image\/","url":"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery","contentUrl":"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery","caption":"admin"},"sameAs":["http:\/\/wp.wsisp.com"],"url":"https:\/\/www.wsisp.com\/helps\/author\/admin"}]}},"_links":{"self":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts\/75927","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/comments?post=75927"}],"version-history":[{"count":0,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts\/75927\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/media\/75907"}],"wp:attachment":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/media?parent=75927"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/categories?post=75927"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/tags?post=75927"},{"taxonomy":"topic","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/topic?post=75927"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}