{"id":53246,"date":"2025-08-12T07:19:40","date_gmt":"2025-08-11T23:19:40","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/53246.html"},"modified":"2025-08-12T07:19:40","modified_gmt":"2025-08-11T23:19:40","slug":"java%e4%b8%ad%e5%af%b9%e8%b1%a1%e5%9e%83%e5%9c%be%e5%88%a4%e6%96%ad%e6%9c%ba%e5%88%b6%e5%8f%8a%e5%ae%9e%e7%8e%b0%e6%96%b9%e5%bc%8f%e6%b7%b1%e5%ba%a6%e8%a7%a3%e6%9e%90","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/53246.html","title":{"rendered":"Java\u4e2d\u5bf9\u8c61\u5783\u573e\u5224\u65ad\u673a\u5236\u53ca\u5b9e\u73b0\u65b9\u5f0f\u6df1\u5ea6\u89e3\u6790"},"content":{"rendered":"<p><img decoding=\"async\" src=\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2025\/08\/20250811231937-689a7a89e067b.png\" alt=\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \/><\/p>\n<\/p>\n<h4>\u6587\u7ae0\u76ee\u5f55<\/h4>\n<ul>\n<li>\n<ul>\n<li>\u4e00\u3001\u5783\u573e\u5224\u65ad\u7684\u57fa\u672c\u6982\u5ff5<\/li>\n<li>\n<ul>\n<li>1.1 \u4ec0\u4e48\u662f\u5783\u573e\u5bf9\u8c61<\/li>\n<li>1.2 \u5224\u65ad\u5bf9\u8c61\u4e3a\u5783\u573e\u7684\u610f\u4e49<\/li>\n<\/ul>\n<\/li>\n<li>\u4e8c\u3001\u5783\u573e\u5224\u65ad\u7684\u4e3b\u8981\u7b97\u6cd5<\/li>\n<li>\n<ul>\n<li>2.1 \u5f15\u7528\u8ba1\u6570\u7b97\u6cd5(Reference Counting)<\/li>\n<li>\n<ul>\n<li>\u5b9e\u73b0\u539f\u7406<\/li>\n<li>\u4f18\u70b9<\/li>\n<li>\u7f3a\u70b9<\/li>\n<li>\u5faa\u73af\u5f15\u7528\u793a\u4f8b<\/li>\n<\/ul>\n<\/li>\n<li>2.2 \u53ef\u8fbe\u6027\u5206\u6790\u7b97\u6cd5(Reachability Analysis)<\/li>\n<li>\n<ul>\n<li>\u5b9e\u73b0\u539f\u7406<\/li>\n<li>GC Roots\u5305\u62ec<\/li>\n<li>\u5b9e\u73b0\u4f2a\u4ee3\u7801<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li>\u4e09\u3001Java\u4e2d\u7684\u5f15\u7528\u7c7b\u578b\u4e0e\u5783\u573e\u5224\u65ad<\/li>\n<li>\n<ul>\n<li>3.1 \u5f3a\u5f15\u7528(Strong Reference)<\/li>\n<li>3.2 \u8f6f\u5f15\u7528(SoftReference)<\/li>\n<li>3.3 \u5f31\u5f15\u7528(WeakReference)<\/li>\n<li>3.4 \u865a\u5f15\u7528(PhantomReference)<\/li>\n<\/ul>\n<\/li>\n<li>\u56db\u3001HotSpot\u865a\u62df\u673a\u7684\u5177\u4f53\u5b9e\u73b0<\/li>\n<li>\n<ul>\n<li>4.1 \u679a\u4e3e\u6839\u8282\u70b9(GC Roots)<\/li>\n<li>4.2 \u53ef\u8fbe\u6027\u5206\u6790\u7684\u5177\u4f53\u8fc7\u7a0b<\/li>\n<li>4.3 \u4e0d\u540c\u6536\u96c6\u5668\u7684\u5b9e\u73b0\u5dee\u5f02<\/li>\n<\/ul>\n<\/li>\n<li>\u4e94\u3001\u5224\u65ad\u8fc7\u7a0b\u4e2d\u7684\u7279\u6b8a\u5904\u7406<\/li>\n<li>\n<ul>\n<li>5.1 \u8bb0\u5fc6\u96c6\u4e0e\u5361\u8868(Remembered Set &amp; Card Table)<\/li>\n<li>5.2 \u5199\u5c4f\u969c(Write Barrier)<\/li>\n<li>5.3 \u5e76\u53d1\u6807\u8bb0\u7684\u6311\u6218\u4e0e\u89e3\u51b3\u65b9\u6848<\/li>\n<\/ul>\n<\/li>\n<li>\u516d\u3001\u5b9e\u9645\u5e94\u7528\u4e2d\u7684\u6ce8\u610f\u4e8b\u9879<\/li>\n<li>\n<ul>\n<li>6.1 \u5185\u5b58\u6cc4\u6f0f\u7684\u5e38\u89c1\u6a21\u5f0f<\/li>\n<li>6.2 \u5224\u65ad\u5bf9\u8c61\u4e3a\u5783\u573e\u7684\u65f6\u673a<\/li>\n<li>6.3 \u76d1\u63a7\u4e0e\u8c03\u8bd5\u5de5\u5177<\/li>\n<\/ul>\n<\/li>\n<li>\u4e03\u3001\u603b\u7ed3&#xff1a;\u4e0d\u540c\u5b9e\u73b0\u65b9\u5f0f\u7684\u5bf9\u6bd4<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>\u5728Java\u4e2d&#xff0c;\u5783\u573e\u6536\u96c6\u5668(Garbage Collector, GC)\u8d1f\u8d23\u81ea\u52a8\u7ba1\u7406\u5185\u5b58&#xff0c;\u8bc6\u522b\u548c\u56de\u6536\u4e0d\u518d\u4f7f\u7528\u7684\u5bf9\u8c61\u3002\u5224\u65ad\u5bf9\u8c61\u662f\u5426\u662f\u5783\u573e\u662f\u5783\u573e\u6536\u96c6\u7684\u57fa\u7840&#xff0c;\u672c\u6587\u5c06\u5168\u9762\u5256\u6790Java\u4e2d\u5224\u65ad\u5bf9\u8c61\u662f\u5426\u4e3a\u5783\u573e\u7684\u5404\u79cd\u65b9\u6cd5\u3001\u5b9e\u73b0\u539f\u7406\u4ee5\u53ca\u4e0d\u540c\u5b9e\u73b0\u65b9\u5f0f\u7684\u533a\u522b\u3002<\/p>\n<h3>\u4e00\u3001\u5783\u573e\u5224\u65ad\u7684\u57fa\u672c\u6982\u5ff5<\/h3>\n<h4>1.1 \u4ec0\u4e48\u662f\u5783\u573e\u5bf9\u8c61<\/h4>\n<p>\u5728Java\u4e2d&#xff0c;\u5783\u573e\u5bf9\u8c61\u6307\u7684\u662f\u7a0b\u5e8f\u4e2d\u4e0d\u518d\u88ab\u4efb\u4f55\u6d3b\u52a8\u5bf9\u8c61\u5f15\u7528\u7684\u5bf9\u8c61&#xff0c;\u8fd9\u4e9b\u5bf9\u8c61\u5df2\u7ecf\u65e0\u6cd5\u88ab\u7a0b\u5e8f\u8bbf\u95ee&#xff0c;\u5360\u7528\u7684\u5185\u5b58\u53ef\u4ee5\u88ab\u5b89\u5168\u56de\u6536\u3002<\/p>\n<h4>1.2 \u5224\u65ad\u5bf9\u8c61\u4e3a\u5783\u573e\u7684\u610f\u4e49<\/h4>\n<li>\u91ca\u653e\u5185\u5b58\u7a7a\u95f4&#xff1a;\u907f\u514d\u5185\u5b58\u6cc4\u6f0f<\/li>\n<li>\u63d0\u9ad8\u5185\u5b58\u5229\u7528\u7387&#xff1a;\u4f7f\u53ef\u7528\u5185\u5b58\u6700\u5927\u5316<\/li>\n<li>\u4fdd\u8bc1\u7a0b\u5e8f\u7a33\u5b9a\u6027&#xff1a;\u9632\u6b62\u5185\u5b58\u6ea2\u51fa(OOM)<\/li>\n<h3>\u4e8c\u3001\u5783\u573e\u5224\u65ad\u7684\u4e3b\u8981\u7b97\u6cd5<\/h3>\n<p>Java\u865a\u62df\u673a\u4e3b\u8981\u4f7f\u7528\u53ef\u8fbe\u6027\u5206\u6790\u7b97\u6cd5\u6765\u5224\u65ad\u5bf9\u8c61\u662f\u5426\u4e3a\u5783\u573e&#xff0c;\u540c\u65f6\u5386\u53f2\u4e0a\u4e5f\u66fe\u4f7f\u7528\u8fc7\u5f15\u7528\u8ba1\u6570\u7b97\u6cd5\u3002<\/p>\n<h4>2.1 \u5f15\u7528\u8ba1\u6570\u7b97\u6cd5(Reference Counting)<\/h4>\n<h5>\u5b9e\u73b0\u539f\u7406<\/h5>\n<ul>\n<li>\u6bcf\u4e2a\u5bf9\u8c61\u7ef4\u62a4\u4e00\u4e2a\u5f15\u7528\u8ba1\u6570\u5668<\/li>\n<li>\u5f53\u88ab\u5f15\u7528\u65f6\u8ba1\u6570\u5668\u52a01<\/li>\n<li>\u5f53\u5f15\u7528\u5931\u6548\u65f6\u8ba1\u6570\u5668\u51cf1<\/li>\n<li>\u8ba1\u6570\u5668\u4e3a0\u65f6\u5224\u5b9a\u4e3a\u5783\u573e<\/li>\n<\/ul>\n<p><span class=\"token comment\">\/\/ \u5f15\u7528\u8ba1\u6570\u4f2a\u4ee3\u7801\u5b9e\u73b0<\/span><br \/>\n<span class=\"token keyword\">class<\/span> <span class=\"token class-name\">ReferenceCountedObject<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">private<\/span> <span class=\"token keyword\">int<\/span> count <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">addReference<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        count<span class=\"token operator\">&#043;&#043;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">removeReference<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        count<span class=\"token operator\">&#8212;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>count <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token function\">reclaim<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ \u56de\u6536\u5bf9\u8c61<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token keyword\">private<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">reclaim<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u91ca\u653e\u8d44\u6e90<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h5>\u4f18\u70b9<\/h5>\n<ul>\n<li>\u5b9e\u73b0\u7b80\u5355<\/li>\n<li>\u5224\u65ad\u9ad8\u6548&#xff0c;\u53ef\u4ee5\u7acb\u5373\u56de\u6536\u5783\u573e<\/li>\n<\/ul>\n<h5>\u7f3a\u70b9<\/h5>\n<ul>\n<li>\u65e0\u6cd5\u89e3\u51b3\u5faa\u73af\u5f15\u7528\u95ee\u9898&#xff1a;\u8fd9\u662fJava\u672a\u91c7\u7528\u6b64\u7b97\u6cd5\u7684\u4e3b\u8981\u539f\u56e0<\/li>\n<li>\u8ba1\u6570\u5668\u7ef4\u62a4\u5f00\u9500\u5927<\/li>\n<\/ul>\n<h5>\u5faa\u73af\u5f15\u7528\u793a\u4f8b<\/h5>\n<p><span class=\"token keyword\">class<\/span> <span class=\"token class-name\">Node<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token class-name\">Node<\/span> next<span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">static<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">main<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">]<\/span> args<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token class-name\">Node<\/span> a <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Node<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token class-name\">Node<\/span> b <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Node<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        a<span class=\"token punctuation\">.<\/span>next <span class=\"token operator\">&#061;<\/span> b<span class=\"token punctuation\">;<\/span><br \/>\n        b<span class=\"token punctuation\">.<\/span>next <span class=\"token operator\">&#061;<\/span> a<span class=\"token punctuation\">;<\/span><br \/>\n        a <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        b <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u6b64\u65f6a\u548cb\u5df2\u65e0\u6cd5\u8bbf\u95ee&#xff0c;\u4f46\u56e0\u4e92\u76f8\u5f15\u7528\u5bfc\u81f4\u8ba1\u6570\u5668\u4e0d\u4e3a0<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h4>2.2 \u53ef\u8fbe\u6027\u5206\u6790\u7b97\u6cd5(Reachability Analysis)<\/h4>\n<h5>\u5b9e\u73b0\u539f\u7406<\/h5>\n<ul>\n<li>\u4ece\u4e00\u7ec4\u79f0\u4e3aGC Roots\u7684\u6839\u5bf9\u8c61\u5f00\u59cb<\/li>\n<li>\u901a\u8fc7\u5f15\u7528\u94fe\u904d\u5386\u6240\u6709\u53ef\u8fbe\u5bf9\u8c61<\/li>\n<li>\u672a\u88ab\u904d\u5386\u5230\u7684\u5bf9\u8c61\u5224\u5b9a\u4e3a\u5783\u573e<\/li>\n<\/ul>\n<p>graph TD<br \/>\n    GC Roots &#8211;&gt; A<br \/>\n    GC Roots &#8211;&gt; B<br \/>\n    A &#8211;&gt; C<br \/>\n    B &#8211;&gt; D<br \/>\n    D &#8211;&gt; E<br \/>\n    F &#8211;&gt; G<br \/>\n    style F stroke:#f00,stroke-width:2px<br \/>\n    style G stroke:#f00,stroke-width:2px<\/p>\n<p>    %% \u8bf4\u660e<br \/>\n    classDef garbage fill:#fdd,stroke:#f00;<br \/>\n    class F,G garbage;<\/p>\n<p>\u4e0a\u56fe\u4e2dF\u548cG\u65e0\u6cd5\u4eceGC Roots\u5230\u8fbe&#xff0c;\u56e0\u6b64\u88ab\u5224\u5b9a\u4e3a\u5783\u573e\u3002<\/p>\n<h5>GC Roots\u5305\u62ec<\/h5>\n<li>\u865a\u62df\u673a\u6808\u4e2d\u5f15\u7528\u7684\u5bf9\u8c61&#xff08;\u5c40\u90e8\u53d8\u91cf&#xff09;<\/li>\n<li>\u65b9\u6cd5\u533a\u4e2d\u7c7b\u9759\u6001\u5c5e\u6027\u5f15\u7528\u7684\u5bf9\u8c61<\/li>\n<li>\u65b9\u6cd5\u533a\u4e2d\u5e38\u91cf\u5f15\u7528\u7684\u5bf9\u8c61<\/li>\n<li>\u672c\u5730\u65b9\u6cd5\u6808\u4e2dJNI\u5f15\u7528\u7684\u5bf9\u8c61<\/li>\n<li>Java\u865a\u62df\u673a\u5185\u90e8\u5f15\u7528&#xff08;\u5982\u57fa\u672c\u7c7b\u578b\u5bf9\u5e94\u7684Class\u5bf9\u8c61&#xff09;<\/li>\n<li>\u88ab\u540c\u6b65\u9501(synchronized)\u6301\u6709\u7684\u5bf9\u8c61<\/li>\n<li>\u53cd\u6620Java\u865a\u62df\u673a\u5185\u90e8\u60c5\u51b5\u7684JMXBean\u7b49<\/li>\n<h5>\u5b9e\u73b0\u4f2a\u4ee3\u7801<\/h5>\n<p><span class=\"token keyword\">void<\/span> <span class=\"token function\">markReachableObjects<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token class-name\">Set<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> marked <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashSet<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token class-name\">Queue<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> toVisit <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">LinkedList<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 1. \u6807\u8bb0GC Roots<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Object<\/span> root <span class=\"token operator\">:<\/span> <span class=\"token function\">getGCRoots<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        marked<span class=\"token punctuation\">.<\/span><span class=\"token function\">add<\/span><span class=\"token punctuation\">(<\/span>root<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        toVisit<span class=\"token punctuation\">.<\/span><span class=\"token function\">add<\/span><span class=\"token punctuation\">(<\/span>root<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 2. \u904d\u5386\u5f15\u7528\u94fe<\/span><br \/>\n    <span class=\"token keyword\">while<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>toVisit<span class=\"token punctuation\">.<\/span><span class=\"token function\">isEmpty<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token class-name\">Object<\/span> obj <span class=\"token operator\">&#061;<\/span> toVisit<span class=\"token punctuation\">.<\/span><span class=\"token function\">poll<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Object<\/span> ref <span class=\"token operator\">:<\/span> <span class=\"token function\">getReferences<\/span><span class=\"token punctuation\">(<\/span>obj<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>marked<span class=\"token punctuation\">.<\/span><span class=\"token function\">contains<\/span><span class=\"token punctuation\">(<\/span>ref<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n                marked<span class=\"token punctuation\">.<\/span><span class=\"token function\">add<\/span><span class=\"token punctuation\">(<\/span>ref<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n                toVisit<span class=\"token punctuation\">.<\/span><span class=\"token function\">add<\/span><span class=\"token punctuation\">(<\/span>ref<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token punctuation\">}<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 3. \u56de\u6536\u672a\u6807\u8bb0\u5bf9\u8c61<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Object<\/span> obj <span class=\"token operator\">:<\/span> <span class=\"token function\">heapObjects<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>marked<span class=\"token punctuation\">.<\/span><span class=\"token function\">contains<\/span><span class=\"token punctuation\">(<\/span>obj<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token function\">reclaim<\/span><span class=\"token punctuation\">(<\/span>obj<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h3>\u4e09\u3001Java\u4e2d\u7684\u5f15\u7528\u7c7b\u578b\u4e0e\u5783\u573e\u5224\u65ad<\/h3>\n<p>Java\u63d0\u4f9b\u4e86\u56db\u79cd\u5f15\u7528\u7c7b\u578b&#xff0c;\u5b83\u4eec\u5bf9\u5783\u573e\u5224\u65ad\u548c\u56de\u6536\u884c\u4e3a\u6709\u4e0d\u540c\u5f71\u54cd&#xff1a;<\/p>\n<table>\n<tr>\u5f15\u7528\u7c7b\u578b\u7c7b\u5783\u573e\u56de\u6536\u884c\u4e3a\u7528\u9014<\/tr>\n<tbody>\n<tr>\n<td>\u5f3a\u5f15\u7528<\/td>\n<td>\u9ed8\u8ba4<\/td>\n<td>\u6c38\u8fdc\u4e0d\u4f1a\u88ab\u56de\u6536<\/td>\n<td>\u666e\u901a\u5bf9\u8c61\u5f15\u7528<\/td>\n<\/tr>\n<tr>\n<td>\u8f6f\u5f15\u7528<\/td>\n<td>SoftReference<\/td>\n<td>\u5185\u5b58\u4e0d\u8db3\u65f6\u56de\u6536<\/td>\n<td>\u5185\u5b58\u654f\u611f\u7f13\u5b58<\/td>\n<\/tr>\n<tr>\n<td>\u5f31\u5f15\u7528<\/td>\n<td>WeakReference<\/td>\n<td>\u4e0b\u6b21GC\u65f6\u56de\u6536<\/td>\n<td>\u89c4\u8303\u5316\u6620\u5c04<\/td>\n<\/tr>\n<tr>\n<td>\u865a\u5f15\u7528<\/td>\n<td>PhantomReference<\/td>\n<td>\u968f\u65f6\u53ef\u80fd\u56de\u6536<\/td>\n<td>\u5bf9\u8c61\u56de\u6536\u8ddf\u8e2a<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4>3.1 \u5f3a\u5f15\u7528(Strong Reference)<\/h4>\n<p><span class=\"token class-name\">Object<\/span> obj <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ \u5f3a\u5f15\u7528<\/span><\/p>\n<ul>\n<li>\u53ea\u8981\u5f3a\u5f15\u7528\u5b58\u5728&#xff0c;\u5bf9\u8c61\u5c31\u4e0d\u4f1a\u88ab\u56de\u6536<\/li>\n<li>\u662f\u9020\u6210\u5185\u5b58\u6cc4\u6f0f\u7684\u4e3b\u8981\u539f\u56e0\u4e4b\u4e00<\/li>\n<\/ul>\n<h4>3.2 \u8f6f\u5f15\u7528(SoftReference)<\/h4>\n<p><span class=\"token class-name\">SoftReference<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> softRef <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">SoftReference<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<ul>\n<li>\u5185\u5b58\u5145\u8db3\u65f6\u4e0d\u4f1a\u88ab\u56de\u6536<\/li>\n<li>\u5f53\u5185\u5b58\u4e0d\u8db3\u65f6&#xff08;OOM\u524d&#xff09;&#xff0c;\u4f1a\u56de\u6536\u8f6f\u5f15\u7528\u5bf9\u8c61<\/li>\n<li>\u9002\u5408\u5b9e\u73b0\u5185\u5b58\u654f\u611f\u7f13\u5b58<\/li>\n<\/ul>\n<h4>3.3 \u5f31\u5f15\u7528(WeakReference)<\/h4>\n<p><span class=\"token class-name\">WeakReference<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> weakRef <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">WeakReference<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<ul>\n<li>\u65e0\u8bba\u5185\u5b58\u662f\u5426\u5145\u8db3&#xff0c;\u53ea\u8981\u53d1\u751fGC\u5c31\u4f1a\u88ab\u56de\u6536<\/li>\n<li>\u5e38\u7528\u4e8eWeakHashMap\u7b49\u573a\u666f<\/li>\n<\/ul>\n<h4>3.4 \u865a\u5f15\u7528(PhantomReference)<\/h4>\n<p><span class=\"token class-name\">PhantomReference<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> phantomRef <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">PhantomReference<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> queue<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<ul>\n<li>\u65e0\u6cd5\u901a\u8fc7\u865a\u5f15\u7528\u83b7\u53d6\u5bf9\u8c61<\/li>\n<li>\u4e3b\u8981\u7528\u4e8e\u8ddf\u8e2a\u5bf9\u8c61\u88ab\u56de\u6536\u7684\u72b6\u6001<\/li>\n<\/ul>\n<h3>\u56db\u3001HotSpot\u865a\u62df\u673a\u7684\u5177\u4f53\u5b9e\u73b0<\/h3>\n<h4>4.1 \u679a\u4e3e\u6839\u8282\u70b9(GC Roots)<\/h4>\n<p>HotSpot\u4f7f\u7528\u51c6\u786e\u5f0fGC(Exact GC)&#xff0c;\u9700\u8981\u77e5\u9053\u54ea\u4e9b\u4f4d\u7f6e\u5b58\u653e\u7740\u5f15\u7528\u3002\u5b9e\u73b0\u65b9\u5f0f&#xff1a;<\/p>\n<li>OopMap\u6570\u636e\u7ed3\u6784&#xff1a;\u8bb0\u5f55\u6808\u548c\u5bc4\u5b58\u5668\u4e2d\u54ea\u4e9b\u4f4d\u7f6e\u662f\u5f15\u7528<\/li>\n<li>\u5b89\u5168\u70b9(Safepoint)&#xff1a;\u53ea\u6709\u5728\u5b89\u5168\u70b9\u624d\u4f1a\u751f\u6210OopMap<\/li>\n<p>\/\/ HotSpot\u4e2dOopMap\u7684\u7b80\u5316\u8868\u793a<br \/>\nclass OopMap {<br \/>\n    intptr_t* _pc;    \/\/ \u6307\u4ee4\u5730\u5740<br \/>\n    BitMap _map;      \/\/ \u5f15\u7528\u4f4d\u7f6e\u4f4d\u56fe<br \/>\n    \/\/ &#8230;<br \/>\n};<\/p>\n<h4>4.2 \u53ef\u8fbe\u6027\u5206\u6790\u7684\u5177\u4f53\u8fc7\u7a0b<\/h4>\n<li>\n<p>\u521d\u59cb\u6807\u8bb0(Initial Mark)&#xff1a;<\/p>\n<ul>\n<li>\u6682\u505c\u6240\u6709\u7ebf\u7a0b(Stop-The-World)<\/li>\n<li>\u6807\u8bb0\u76f4\u63a5\u4eceGC Roots\u53ef\u8fbe\u7684\u5bf9\u8c61<\/li>\n<li>\u65f6\u95f4\u5f88\u77ed<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5e76\u53d1\u6807\u8bb0(Concurrent Mark)&#xff1a;<\/p>\n<ul>\n<li>\u6062\u590d\u5e94\u7528\u7ebf\u7a0b<\/li>\n<li>\u4ece\u521d\u59cb\u6807\u8bb0\u7684\u5bf9\u8c61\u5f00\u59cb\u904d\u5386\u6574\u4e2a\u5bf9\u8c61\u56fe<\/li>\n<li>\u4e0e\u5e94\u7528\u7ebf\u7a0b\u5e76\u53d1\u6267\u884c<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u6700\u7ec8\u6807\u8bb0(Final Mark)&#xff1a;<\/p>\n<ul>\n<li>\u518d\u6b21\u6682\u505c\u6240\u6709\u7ebf\u7a0b<\/li>\n<li>\u5904\u7406\u5e76\u53d1\u6807\u8bb0\u671f\u95f4\u53d8\u5316\u7684\u5f15\u7528<\/li>\n<li>\u4f7f\u7528\u589e\u91cf\u66f4\u65b0(Incremental Update)\u6216\u539f\u59cb\u5feb\u7167(Snapshot-At-The-Beginning)\u7b97\u6cd5<\/li>\n<\/ul>\n<\/li>\n<h4>4.3 \u4e0d\u540c\u6536\u96c6\u5668\u7684\u5b9e\u73b0\u5dee\u5f02<\/h4>\n<table>\n<tr>\u6536\u96c6\u5668\u5783\u573e\u5224\u65ad\u5b9e\u73b0\u7279\u70b9\u9002\u7528\u573a\u666f<\/tr>\n<tbody>\n<tr>\n<td>Serial<\/td>\n<td>\u5355\u7ebf\u7a0bSTW\u6807\u8bb0<\/td>\n<td>\u5ba2\u6237\u7aef\u6a21\u5f0f<\/td>\n<\/tr>\n<tr>\n<td>ParNew<\/td>\n<td>\u591a\u7ebf\u7a0b\u5e76\u884c\u6807\u8bb0<\/td>\n<td>\u65b0\u751f\u4ee3\u6536\u96c6<\/td>\n<\/tr>\n<tr>\n<td>CMS<\/td>\n<td>\u5e76\u53d1\u6807\u8bb0&#xff0c;\u51cf\u5c11\u505c\u987f<\/td>\n<td>\u8001\u5e74\u4ee3\u4f4e\u5ef6\u8fdf<\/td>\n<\/tr>\n<tr>\n<td>G1<\/td>\n<td>\u5206\u533a\u589e\u91cf\u6807\u8bb0<\/td>\n<td>\u5927\u5806\u5e73\u8861\u541e\u5410\u4e0e\u5ef6\u8fdf<\/td>\n<\/tr>\n<tr>\n<td>ZGC<\/td>\n<td>\u5e76\u53d1\u6807\u8bb0&#xff0c;\u67d3\u8272\u6307\u9488<\/td>\n<td>\u8d85\u5927\u5806\u4f4e\u5ef6\u8fdf<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>\u4e94\u3001\u5224\u65ad\u8fc7\u7a0b\u4e2d\u7684\u7279\u6b8a\u5904\u7406<\/h3>\n<h4>5.1 \u8bb0\u5fc6\u96c6\u4e0e\u5361\u8868(Remembered Set &amp; Card Table)<\/h4>\n<p>\u89e3\u51b3\u8de8\u4ee3\u5f15\u7528\u95ee\u9898&#xff1a;<\/p>\n<ul>\n<li>\u8bb0\u5fc6\u96c6&#xff1a;\u8bb0\u5f55\u4ece\u975e\u6536\u96c6\u533a\u57df\u6307\u5411\u6536\u96c6\u533a\u57df\u7684\u5f15\u7528<\/li>\n<li>\u5361\u8868&#xff1a;\u662f\u8bb0\u5fc6\u96c6\u7684\u4e00\u79cd\u5b9e\u73b0&#xff0c;\u5c06\u5806\u5212\u5206\u4e3a512\u5b57\u8282\u7684\u5361\u9875<\/li>\n<\/ul>\n<p>\/\/ HotSpot\u4e2d\u5361\u8868\u7684\u7b80\u5316\u8868\u793a<br \/>\nbyte* _card_table;<br \/>\nbyte* _card_table_start;<br \/>\nbyte* _card_table_end;<\/p>\n<h4>5.2 \u5199\u5c4f\u969c(Write Barrier)<\/h4>\n<p>\u7ef4\u62a4\u5361\u8868\u4e00\u81f4\u6027\u7684\u673a\u5236&#xff1a;<\/p>\n<p><span class=\"token comment\">\/\/ \u5199\u5c4f\u969c\u4f2a\u4ee3\u7801<\/span><br \/>\n<span class=\"token keyword\">void<\/span> <span class=\"token function\">post_write_barrier<\/span><span class=\"token punctuation\">(<\/span>oop<span class=\"token operator\">*<\/span> field<span class=\"token punctuation\">,<\/span> oop new_value<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">cross_generation_ref<\/span><span class=\"token punctuation\">(<\/span>field<span class=\"token punctuation\">,<\/span> new_value<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        card_table<span class=\"token punctuation\">.<\/span><span class=\"token function\">mark_dirty<\/span><span class=\"token punctuation\">(<\/span>field<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h4>5.3 \u5e76\u53d1\u6807\u8bb0\u7684\u6311\u6218\u4e0e\u89e3\u51b3\u65b9\u6848<\/h4>\n<p>\u95ee\u9898&#xff1a;\u5e76\u53d1\u6807\u8bb0\u671f\u95f4\u5bf9\u8c61\u56fe\u53ef\u80fd\u53d8\u5316<\/p>\n<p>\u89e3\u51b3\u65b9\u6848&#xff1a;<\/p>\n<li>\u589e\u91cf\u66f4\u65b0(Incremental Update)&#xff1a;\u8bb0\u5f55\u65b0\u589e\u7684\u5f15\u7528<\/li>\n<li>\u539f\u59cb\u5feb\u7167(SATB)&#xff1a;\u4ee5\u6807\u8bb0\u5f00\u59cb\u65f6\u5bf9\u8c61\u56fe\u4e3a\u51c6<\/li>\n<p>  #mermaid-svg-9LV1Z1Y5ZQPDedGg {font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:16px;fill:#333;}#mermaid-svg-9LV1Z1Y5ZQPDedGg .error-icon{fill:#552222;}#mermaid-svg-9LV1Z1Y5ZQPDedGg .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-9LV1Z1Y5ZQPDedGg .edge-thickness-normal{stroke-width:2px;}#mermaid-svg-9LV1Z1Y5ZQPDedGg .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-9LV1Z1Y5ZQPDedGg .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-9LV1Z1Y5ZQPDedGg 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#aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-9LV1Z1Y5ZQPDedGg :root{&#8211;mermaid-font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;}<\/p>\n<p>         <span id=\"L-L-A-B\" class=\"edgeLabel L-LS-A&#039; L-LE-B\"><\/span><\/p>\n<p>         <span id=\"L-L-A-C\" class=\"edgeLabel L-LS-A&#039; L-LE-C\"><\/span><\/p>\n<p>         <span id=\"L-L-B-D\" class=\"edgeLabel L-LS-B&#039; L-LE-D\"><\/span><\/p>\n<p>         <span id=\"L-L-C-E\" class=\"edgeLabel L-LS-C&#039; L-LE-E\"><\/span><\/p>\n<p>          \u5e76\u53d1\u6807\u8bb0\u95ee\u9898<\/p>\n<p>          \u589e\u91cf\u66f4\u65b0<\/p>\n<p>          \u539f\u59cb\u5feb\u7167<\/p>\n<p>          \u8bb0\u5f55\u65b0\u5f15\u7528<\/p>\n<p>          \u8bb0\u5f55\u5220\u9664\u5f15\u7528<\/p>\n<h3>\u516d\u3001\u5b9e\u9645\u5e94\u7528\u4e2d\u7684\u6ce8\u610f\u4e8b\u9879<\/h3>\n<h4>6.1 \u5185\u5b58\u6cc4\u6f0f\u7684\u5e38\u89c1\u6a21\u5f0f<\/h4>\n<p>\u5373\u4f7f\u4f7f\u7528\u53ef\u8fbe\u6027\u5206\u6790&#xff0c;\u4ecd\u53ef\u80fd\u56e0\u4ee5\u4e0b\u60c5\u51b5\u5bfc\u81f4\u5185\u5b58\u6cc4\u6f0f&#xff1a;<\/p>\n<li>\u9759\u6001\u96c6\u5408&#xff1a;\u9759\u6001Map\u3001List\u7b49\u6301\u6709\u5bf9\u8c61\u5f15\u7528<\/li>\n<li>\u672a\u5173\u95ed\u8d44\u6e90&#xff1a;\u6570\u636e\u5e93\u8fde\u63a5\u3001\u6587\u4ef6\u6d41\u7b49<\/li>\n<li>\u76d1\u542c\u5668\u672a\u6ce8\u9500&#xff1a;\u4e8b\u4ef6\u76d1\u542c\u5668\u672a\u88ab\u79fb\u9664<\/li>\n<li>\u5185\u90e8\u7c7b\u5f15\u7528&#xff1a;\u975e\u9759\u6001\u5185\u90e8\u7c7b\u9690\u5f0f\u6301\u6709\u5916\u90e8\u7c7b\u5f15\u7528<\/li>\n<p><span class=\"token comment\">\/\/ \u5178\u578b\u5185\u5b58\u6cc4\u6f0f\u793a\u4f8b<\/span><br \/>\n<span class=\"token keyword\">class<\/span> <span class=\"token class-name\">LeakExample<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">static<\/span> <span class=\"token class-name\">List<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> cache <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">ArrayList<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token keyword\">void<\/span> <span class=\"token function\">populateCache<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> i <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span> i <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">1000<\/span><span class=\"token punctuation\">;<\/span> i<span class=\"token operator\">&#043;&#043;<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            cache<span class=\"token punctuation\">.<\/span><span class=\"token function\">add<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">new<\/span> <span class=\"token keyword\">byte<\/span><span class=\"token punctuation\">[<\/span><span class=\"token number\">1024<\/span> <span class=\"token operator\">*<\/span> <span class=\"token number\">1024<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ 1MB<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h4>6.2 \u5224\u65ad\u5bf9\u8c61\u4e3a\u5783\u573e\u7684\u65f6\u673a<\/h4>\n<li>\u65b0\u751f\u4ee3\u6536\u96c6(Minor GC)&#xff1a;Eden\u533a\u6ee1\u65f6\u89e6\u53d1<\/li>\n<li>\u8001\u5e74\u4ee3\u6536\u96c6(Full GC)&#xff1a;\u8001\u5e74\u4ee3\u7a7a\u95f4\u4e0d\u8db3\u65f6\u89e6\u53d1<\/li>\n<li>System.gc()&#xff1a;\u5efa\u8baeJVM\u6267\u884cGC&#xff08;\u4e0d\u4fdd\u8bc1\u7acb\u5373\u6267\u884c&#xff09;<\/li>\n<li>\u5143\u7a7a\u95f4\u4e0d\u8db3&#xff1a;\u7c7b\u5143\u6570\u636e\u5360\u7528\u8d85\u8fc7MaxMetaspaceSize<\/li>\n<h4>6.3 \u76d1\u63a7\u4e0e\u8c03\u8bd5\u5de5\u5177<\/h4>\n<li>\n<p>jmap&#xff1a;\u67e5\u770b\u5806\u5185\u5b58\u5206\u5e03<\/p>\n<p> jmap -histo <span class=\"token operator\">&lt;<\/span>pid<span class=\"token operator\">&gt;<\/span>\n 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