{"id":118895,"date":"2026-10-28T10:57:27","date_gmt":"2026-10-28T02:57:27","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/118895.html"},"modified":"2026-10-28T10:57:27","modified_gmt":"2026-10-28T02:57:27","slug":"c-%e5%8e%9f%e5%ad%90%e6%93%8d%e4%bd%9c%e3%80%81%e5%86%85%e5%ad%98%e6%a8%a1%e5%9e%8b%e4%b8%8e%e6%97%a0%e9%94%81%e5%b9%b6%e5%8f%91%e7%bc%96%e7%a8%8b","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/118895.html","title":{"rendered":"C++ \u539f\u5b50\u64cd\u4f5c\u3001\u5185\u5b58\u6a21\u578b\u4e0e\u65e0\u9501\u5e76\u53d1\u7f16\u7a0b"},"content":{"rendered":"

\u4e00\u3001\u5e76\u53d1\u7f16\u7a0b\u7684\u57fa\u7840：\u539f\u5b50\u6027\u3001\u6570\u636e\u7ade\u4e89\u4e0e\u7ebf\u7a0b\u5b89\u5168<\/h3>\n

\u539f\u5b50\u64cd\u4f5c（Atomic Operation）\u662f\u73b0\u4ee3 C++ \u5e76\u53d1\u7f16\u7a0b\u7684\u91cd\u8981\u57fa\u7840\u3002\u5b83\u4e0d\u4ec5\u7528\u4e8e\u5b9e\u73b0\u7ebf\u7a0b\u5b89\u5168\u7684\u8ba1\u6570\u5668\u3001\u72b6\u6001\u6807\u5fd7，\u8fd8\u53ef\u4ee5\u4e0e\u5185\u5b58\u5e8f\u914d\u5408，\u6784\u5efa\u751f\u4ea7\u8005\u2014\u6d88\u8d39\u8005\u6a21\u578b\u3001\u65e0\u9501\u961f\u5217\u3001\u5171\u4eab\u72b6\u6001\u53d1\u5e03\u673a\u5236\u7b49\u5e76\u53d1\u7cfb\u7edf\u3002<\/p>\n

\u4f46\u9700\u8981\u660e\u786e：\u539f\u5b50\u64cd\u4f5c\u4e0d\u7b49\u4e8e\u7ebf\u7a0b\u5b89\u5168，\u7ebf\u7a0b\u5b89\u5168\u4e0d\u7b49\u4e8e\u65e0\u9501，\u65e0\u9501\u4e5f\u4e0d\u7b49\u4e8e\u6027\u80fd\u66f4\u9ad8\u3002<\/p>\n

\u8981\u7406\u89e3\u73b0\u4ee3 C++ \u539f\u5b50\u64cd\u4f5c，\u9996\u5148\u9700\u8981\u533a\u5206\u51e0\u4e2a\u57fa\u672c\u6982\u5ff5\u3002<\/p>\n

1.1 \u4e3a\u4ec0\u4e48\u666e\u901a\u53d8\u91cf\u7684\u81ea\u589e\u4e0d\u662f\u539f\u5b50\u64cd\u4f5c？<\/h4>\n

\u8003\u8651\u4e0b\u9762\u7684\u4ee3\u7801：<\/p>\n

#<\/span>include<\/span> <thread><\/span><\/span><\/p>\n

int<\/span> count =<\/span> 0<\/span>;<\/span><\/p>\n

void<\/span> increment<\/span>(<\/span>)<\/span> {<\/span>
\n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 10000<\/span>;<\/span> ++<\/span>i)<\/span> {<\/span>
\n ++<\/span>count;<\/span>
\n }<\/span>
\n}<\/span><\/p>\n

int<\/span> main<\/span>(<\/span>)<\/span> {<\/span>
\n std::<\/span>thread t1<\/span>(<\/span>increment)<\/span>;<\/span>
\n std::<\/span>thread t2<\/span>(<\/span>increment)<\/span>;<\/span><\/p>\n

t1.<\/span>join<\/span>(<\/span>)<\/span>;<\/span>
\n t2.<\/span>join<\/span>(<\/span>)<\/span>;<\/span>
\n}<\/span><\/p>\n

\u4ece\u6e90\u7801\u770b，++count \u4f3c\u4e4e\u53ea\u662f\u4e00\u4e2a\u7b80\u5355\u64cd\u4f5c，\u4f46\u5b83\u5b9e\u9645\u4e0a\u5305\u542b\u8bfb\u53d6\u3001\u8ba1\u7b97\u548c\u5199\u56de\u7b49\u903b\u8f91\u3002<\/p>\n

\u53ef\u4ee5\u5c06\u5176\u62bd\u8c61\u4e3a：<\/p>\n

\u8bfb\u53d6 count
\n \u2193
\n\u8ba1\u7b97 count + 1
\n \u2193
\n\u5199\u56de count<\/p>\n

\u5047\u8bbe\u4e24\u4e2a\u7ebf\u7a0b\u540c\u65f6\u6267\u884c：<\/p>\n

\u7ebf\u7a0b A \u7ebf\u7a0b B
\n \u2502 \u2502
\n\u8bfb\u53d6 count = 0 \u8bfb\u53d6 count = 0
\n \u2502 \u2502
\n\u8ba1\u7b97\u5f97\u5230 1 \u8ba1\u7b97\u5f97\u5230 1
\n \u2502 \u2502
\n\u5199\u56de count = 1 \u5199\u56de count = 1<\/p>\n

\u6700\u7ec8 count \u53ef\u80fd\u53ea\u589e\u52a0\u4e00\u6b21，\u800c\u4e0d\u662f\u4e24\u6b21\u3002<\/p>\n

\u4f46\u5728 C++ \u4e2d，\u8fd9\u4e2a\u4f8b\u5b50\u8fd8\u5b58\u5728\u66f4\u4e25\u91cd\u7684\u95ee\u9898：\u4e24\u4e2a\u7ebf\u7a0b\u5bf9\u540c\u4e00\u4e2a\u975e\u539f\u5b50\u5bf9\u8c61\u8fdb\u884c\u65e0\u540c\u6b65\u7684\u51b2\u7a81\u8bbf\u95ee，\u6784\u6210\u6570\u636e\u7ade\u4e89（Data Race），\u7a0b\u5e8f\u884c\u4e3a\u5c5e\u4e8e\u672a\u5b9a\u4e49\u884c\u4e3a（Undefined Behavior，UB）\u3002<\/p>\n

\u56e0\u6b64，\u4e0d\u80fd\u7b80\u5355\u5730\u8ba4\u4e3a\u7a0b\u5e8f\u53ea\u662f\u201c\u5076\u5c14\u7b97\u9519\u201d\u3002\u7f16\u8bd1\u5668\u53ef\u4ee5\u57fa\u4e8e\u4e0d\u5b58\u5728\u6570\u636e\u7ade\u4e89\u7684\u8bed\u8a00\u89c4\u5219\u8fdb\u884c\u4f18\u5316，\u5b9e\u9645\u884c\u4e3a\u53ef\u80fd\u8d85\u51fa\u76f4\u89c9\u9884\u671f\u3002<\/p>\n

1.2 \u539f\u5b50\u6027\u5230\u5e95\u610f\u5473\u7740\u4ec0\u4e48？<\/h4>\n

\u539f\u5b50\u6027\u8981\u6c42\u4e00\u6b21\u539f\u5b50\u64cd\u4f5c\u5728\u5e76\u53d1\u89c2\u5bdf\u4e0b\u5177\u6709\u4e0d\u53ef\u5206\u5272\u7684\u8bed\u4e49\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

std::<\/span>atomic<<\/span>int<\/span>><\/span> count{<\/span>0<\/span>}<\/span>;<\/span><\/p>\n

void<\/span> increment<\/span>(<\/span>)<\/span> {<\/span>
\n for<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 10000<\/span>;<\/span> ++<\/span>i)<\/span> {<\/span>
\n count.<\/span>fetch_add<\/span>(<\/span>1<\/span>,<\/span> std::<\/span>memory_order_relaxed)<\/span>;<\/span>
\n }<\/span>
\n}<\/span><\/p>\n

\u4e24\u4e2a\u7ebf\u7a0b\u5404\u6267\u884c 10000 \u6b21\u81ea\u589e，\u6700\u7ec8\u7ed3\u679c\u5fc5\u7136\u4e3a 20000\u3002<\/p>\n

\u8fd9\u91cc\u7684\u5173\u952e\u4e0d\u662f CPU \u7edd\u5bf9\u4e0d\u80fd\u88ab\u4e2d\u65ad，\u800c\u662f\u6bcf\u6b21 fetch_add() \u90fd\u4f5c\u4e3a\u4e00\u4e2a\u4e0d\u53ef\u5206\u5272\u7684\u539f\u5b50\u8bfb\u2014\u6539\u2014\u5199\u64cd\u4f5c\u53c2\u4e0e\u5e76\u53d1\u6267\u884c\u3002<\/p>\n

\u539f\u5b50\u64cd\u4f5c\u751a\u81f3\u53ef\u80fd\u7531\u591a\u6761\u673a\u5668\u6307\u4ee4\u6216\u8fd0\u884c\u5e93\u4ee3\u7801\u5b9e\u73b0\u3002C++ \u4fdd\u8bc1\u7684\u662f\u76f8\u5e94\u7684\u62bd\u8c61\u8bed\u4e49，\u800c\u4e0d\u662f\u8981\u6c42\u6bcf\u4e2a\u64cd\u4f5c\u90fd\u5bf9\u5e94\u4e00\u6761 CPU \u6307\u4ee4\u3002<\/p>\n

1.3 \u533a\u5206\u56db\u4e2a\u6982\u5ff5<\/h4>\n\n\u6982\u5ff5\u542b\u4e49<\/tr>\n\n\n\n\n\n
\u539f\u5b50\u6027（Atomicity）<\/td>\n\u5355\u6b21\u64cd\u4f5c\u4e0d\u53ef\u5206\u5272\u5730\u751f\u6548<\/td>\n<\/tr>\n
\u53ef\u89c1\u6027（Visibility）<\/td>\n\u7ebf\u7a0b\u80fd\u591f\u5728\u89c4\u5b9a\u7684\u540c\u6b65\u6761\u4ef6\u4e0b\u89c2\u5bdf\u5230\u5176\u4ed6\u7ebf\u7a0b\u7684\u5199\u5165<\/td>\n<\/tr>\n
\u6709\u5e8f\u6027（Ordering）<\/td>\n\u5bf9\u4e0d\u540c\u5185\u5b58\u8bbf\u95ee\u65bd\u52a0\u89c4\u5b9a\u7684\u987a\u5e8f\u7ea6\u675f<\/td>\n<\/tr>\n
\u7ebf\u7a0b\u5b89\u5168（Thread Safety）<\/td>\n\u5e76\u53d1\u8bbf\u95ee\u6574\u4f53\u6ee1\u8db3\u7a0b\u5e8f\u8981\u6c42，\u4e0d\u4ea7\u751f\u672a\u5b9a\u4e49\u884c\u4e3a\u6216\u903b\u8f91\u9519\u8bef<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u539f\u5b50\u64cd\u4f5c\u89e3\u51b3\u7684\u662f\u64cd\u4f5c\u672c\u8eab\u7684\u5e76\u53d1\u8bed\u4e49\u95ee\u9898\u3002\u6574\u4e2a\u4e1a\u52a1\u903b\u8f91\u662f\u5426\u7ebf\u7a0b\u5b89\u5168，\u8fd8\u9700\u8981\u5206\u6790\u540c\u6b65\u5173\u7cfb\u3001\u6570\u636e\u4f9d\u8d56\u4e0e\u5bf9\u8c61\u751f\u547d\u5468\u671f\u3002<\/p>\n

\u4e8c\u3001std::atomic \u7684\u5b9e\u73b0\u673a\u5236\u4e0e API<\/h3>\n

C++11 \u5f15\u5165\u4e86 <atomic>，\u63d0\u4f9b\u7edf\u4e00\u7684\u539f\u5b50\u64cd\u4f5c\u63a5\u53e3\u3002<\/p>\n

2.1 std::atomic \u652f\u6301\u54ea\u4e9b\u7c7b\u578b？<\/h4>\n

\u4e3b\u6a21\u677f std::atomic<T> \u8981\u6c42 T \u6ee1\u8db3\u53ef\u5e73\u51e1\u590d\u5236（Trivially Copyable）\u7b49\u6807\u51c6\u7ea6\u675f\u3002<\/p>\n

\u5e38\u89c1\u652f\u6301\u7c7b\u578b\u5305\u62ec：<\/p>\n

    \n
  • \u6574\u6570\u7c7b\u578b，\u5982 int\u3001long\u3002<\/li>\n
  • \u5e03\u5c14\u7c7b\u578b，\u5982 bool\u3002<\/li>\n
  • \u6307\u9488\u7c7b\u578b，\u5982 int*\u3002<\/li>\n
  • \u6ee1\u8db3\u8981\u6c42\u7684\u81ea\u5b9a\u4e49\u7ed3\u6784\u4f53\u3002<\/li>\n<\/ul>\n

    \u4f8b\u5982：<\/p>\n

    struct<\/span> Point<\/span> {<\/span>
    \n int<\/span> x;<\/span>
    \n int<\/span> y;<\/span>
    \n}<\/span>;<\/span><\/p>\n

    std::<\/span>atomic<<\/span>int<\/span>><\/span> counter{<\/span>0<\/span>}<\/span>;<\/span>
    \nstd::<\/span>atomic<<\/span>bool<\/span>><\/span> ready{<\/span>false<\/span>}<\/span>;<\/span>
    \nstd::<\/span>atomic<<\/span>int<\/span>*<\/span>><\/span> ptr{<\/span>nullptr<\/span>}<\/span>;<\/span>
    \nstd::<\/span>atomic<<\/span>Point><\/span> point{<\/span>Point{<\/span>0<\/span>,<\/span> 0<\/span>}<\/span>}<\/span>;<\/span><\/p>\n

    \u5bf9\u4e8e std::atomic<Point>，\u6574\u4e2a Point \u5bf9\u8c61\u53ef\u4ee5\u4f5c\u4e3a\u4e00\u6b21\u539f\u5b50\u64cd\u4f5c\u7684\u5bf9\u8c61，\u800c\u4e0d\u5fc5\u5206\u522b\u66f4\u65b0 x \u548c y\u3002<\/p>\n

    \u4f46\u8fd9\u4e0d\u4ee3\u8868\u5b83\u5fc5\u7136\u7531\u4e00\u6761\u673a\u5668\u6307\u4ee4\u5b9e\u73b0，\u4e5f\u4e0d\u4ee3\u8868\u5b83\u5fc5\u7136\u65e0\u9501\u3002<\/p>\n

    std::atomic<std::string> \u5219\u4e0d\u7b26\u5408\u4e3b\u6a21\u677f\u7684\u53ef\u5e73\u51e1\u590d\u5236\u8981\u6c42，\u4e0d\u80fd\u76f4\u63a5\u8fd9\u6837\u4f7f\u7528\u3002<\/p>\n

    \u73b0\u4ee3 C++ \u8fd8\u63d0\u4f9b\u4e13\u95e8\u7684\u539f\u5b50\u7c7b\u578b，\u4f8b\u5982 C++20 \u7684 std::atomic<std::shared_ptr<T>>，\u5b83\u5c5e\u4e8e\u4e13\u95e8\u5316\u63a5\u53e3，\u4e0d\u80fd\u4ec5\u4f9d\u636e\u4e3b\u6a21\u677f\u7684\u7c7b\u578b\u89c4\u5219\u5224\u65ad\u3002<\/p>\n

    2.2 \u5e38\u7528\u539f\u5b50\u64cd\u4f5c<\/h4>\n\n\u64cd\u4f5c\u63a5\u53e3\u4f5c\u7528<\/tr>\n\n\n\n\n\n\n\n
    \u539f\u5b50\u52a0\u8f7d<\/td>\nload()<\/td>\n\u539f\u5b50\u8bfb\u53d6<\/td>\n<\/tr>\n
    \u539f\u5b50\u5b58\u50a8<\/td>\nstore()<\/td>\n\u539f\u5b50\u5199\u5165<\/td>\n<\/tr>\n
    \u539f\u5b50\u4ea4\u6362<\/td>\nexchange()<\/td>\n\u5199\u5165\u65b0\u503c\u5e76\u8fd4\u56de\u65e7\u503c<\/td>\n<\/tr>\n
    \u539f\u5b50\u52a0\u51cf<\/td>\nfetch_add()\u3001fetch_sub()<\/td>\n\u539f\u5b50\u8bfb\u2014\u6539\u2014\u5199<\/td>\n<\/tr>\n
    \u6bd4\u8f83\u5e76\u4ea4\u6362<\/td>\ncompare_exchange_weak()<\/td>\n\u6761\u4ef6\u6210\u7acb\u65f6\u66f4\u65b0，\u5426\u5219\u62a5\u544a\u5931\u8d25<\/td>\n<\/tr>\n
    \u6bd4\u8f83\u5e76\u4ea4\u6362<\/td>\ncompare_exchange_strong()<\/td>\n\u540c\u6837\u8fdb\u884c\u6761\u4ef6\u66f4\u65b0，\u4f46\u4e0d\u5141\u8bb8\u4ec5\u56e0\u865a\u5047\u5931\u8d25\u800c\u8fd4\u56de\u5931\u8d25<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    \u4f8b\u5982：<\/p>\n

    std::<\/span>atomic<<\/span>int<\/span>><\/span> value{<\/span>10<\/span>}<\/span>;<\/span><\/p>\n

    int<\/span> old =<\/span> value.<\/span>exchange<\/span>(<\/span>20<\/span>)<\/span>;<\/span>
    \n\/\/ old == 10，value == 20<\/span><\/p>\n

    int<\/span> previous =<\/span> value.<\/span>fetch_add<\/span>(<\/span>5<\/span>)<\/span>;<\/span>
    \n\/\/ previous == 20，value == 25<\/span><\/p>\n

    \u6ce8\u610f，fetch_add() \u8fd4\u56de\u7684\u662f\u64cd\u4f5c\u524d\u7684\u503c\u3002<\/p>\n

    \u5bf9\u6574\u6570\u539f\u5b50\u53d8\u91cf\u4f7f\u7528\u524d\u7f6e\u81ea\u589e ++value，\u8868\u8fbe\u5f0f\u7ed3\u679c\u5219\u662f\u81ea\u589e\u540e\u7684\u503c\u3002<\/p>\n

    2.3 \u539f\u5b50\u64cd\u4f5c\u4e3a\u4ec0\u4e48\u4e0d\u4e00\u5b9a\u65e0\u9501？<\/h4>\n

    std::atomic<T> \u89c4\u5b9a\u7684\u662f\u539f\u5b50\u8bed\u4e49，\u4e0d\u4fdd\u8bc1\u6240\u6709\u7c7b\u578b\u7684\u64cd\u4f5c\u90fd\u901a\u8fc7\u65e0\u9501 CPU \u6307\u4ee4\u5b8c\u6210\u3002<\/p>\n

    C++ \u63d0\u4f9b\u4e86\u4e24\u4e2a\u91cd\u8981\u63a5\u53e3：<\/p>\n

    #<\/span>include<\/span> <atomic><\/span><\/span>
    \n#<\/span>include<\/span> <iostream><\/span><\/span><\/p>\n

    int<\/span> main<\/span>(<\/span>)<\/span> {<\/span>
    \n std::<\/span>atomic<<\/span>int<\/span>><\/span> value{<\/span>0<\/span>}<\/span>;<\/span><\/p>\n

    std::<\/span>cout <<<\/span> std::<\/span>boolalpha
    \n <<<\/span> value.<\/span>is_lock_free<\/span>(<\/span>)<\/span> <<<\/span> '\\\\n'<\/span>;<\/span><\/p>\n

    std::<\/span>cout
    \n <<<\/span> std::<\/span>atomic<<\/span>int<\/span>><\/span>::<\/span>is_always_lock_free
    \n <<<\/span> '\\\\n'<\/span>;<\/span>
    \n}<\/span><\/p>\n

      \n
    • is_lock_free()：\u68c0\u67e5\u5f53\u524d\u539f\u5b50\u5bf9\u8c61\u7684\u76f8\u5173\u64cd\u4f5c\u662f\u5426\u65e0\u9501\u3002<\/li>\n
    • is_always_lock_free：\u7f16\u8bd1\u671f\u5e38\u91cf，\u8868\u793a\u8be5\u539f\u5b50\u7c7b\u578b\u7684\u64cd\u4f5c\u662f\u5426\u59cb\u7ec8\u65e0\u9501\u3002<\/li>\n<\/ul>\n

      \u5177\u4f53\u7ed3\u679c\u53d6\u51b3\u4e8e\u5e73\u53f0\u3001\u7c7b\u578b\u3001\u5bf9\u9f50\u8981\u6c42\u53ca\u5b9e\u73b0\u3002<\/p>\n

      std::atomic_flag \u662f C++ \u4e2d\u4fdd\u8bc1\u65e0\u9501\u7684\u539f\u5b50\u7c7b\u578b，\u4f46\u5b83\u7684\u65e0\u9501\u5c5e\u6027\u5e76\u4e0d\u610f\u5473\u7740\u7528\u5b83\u5b9e\u73b0\u7684\u6574\u4e2a\u7b97\u6cd5\u4e00\u5b9a\u65e0\u9501\u6216\u9ad8\u6548\u3002<\/p>\n

      2.4 \u539f\u5b50\u64cd\u4f5c\u7684\u786c\u4ef6\u652f\u6491<\/h4>\n

      C++ \u6807\u51c6\u4e0d\u8981\u6c42\u6240\u6709\u5904\u7406\u5668\u4f7f\u7528\u540c\u4e00\u79cd\u539f\u5b50\u5b9e\u73b0\u3002<\/p>\n

      \u5728\u5e38\u89c1\u67b6\u6784\u4e2d：<\/p>\n

        \n
      • x86-64：\u539f\u5b50\u8bfb\u2014\u6539\u2014\u5199\u64cd\u4f5c\u53ef\u80fd\u4f7f\u7528 LOCK XADD\u3001LOCK CMPXCHG \u7b49\u6307\u4ee4\u3002\u5bf9\u4e8e\u53ef\u7f13\u5b58\u5185\u5b58，\u73b0\u4ee3\u5904\u7406\u5668\u901a\u5e38\u501f\u52a9\u7f13\u5b58\u4e00\u81f4\u6027\u673a\u5236\u5b9e\u73b0\u9501\u5b9a\u64cd\u4f5c，\u800c\u4e0d\u662f\u7b80\u5355\u5730\u9501\u4f4f\u6574\u6761\u5185\u5b58\u603b\u7ebf\u3002<\/li>\n
      • ARM：\u53ef\u80fd\u4f7f\u7528 LDXR\/STXR\u3001\u5e26 Acquire\/Release \u8bed\u4e49\u7684\u72ec\u5360\u8bbf\u95ee\u6307\u4ee4，\u6216\u8005 ARMv8.1-A \u5f15\u5165\u7684 LSE \u539f\u5b50\u6307\u4ee4\u3002<\/li>\n
      • \u4e0d\u652f\u6301\u9ad8\u6548\u539f\u5b50\u64cd\u4f5c\u7684\u7c7b\u578b：\u7f16\u8bd1\u5668\u6216\u8fd0\u884c\u5e93\u53ef\u80fd\u4f7f\u7528\u5185\u90e8\u9501\u7b49\u673a\u5236\u5b8c\u6210\u64cd\u4f5c\u3002<\/li>\n<\/ul>\n

        \u5177\u4f53\u6307\u4ee4\u53d6\u51b3\u4e8e\u76ee\u6807\u67b6\u6784\u3001\u7f16\u8bd1\u5668\u3001\u4f18\u5316\u9009\u9879\u3001\u5185\u5b58\u5e8f\u548c\u539f\u5b50\u7c7b\u578b\u3002<\/p>\n

        \u56e0\u6b64，\u6b63\u786e\u7684\u7406\u89e3\u662f：<\/p>\n

        C++ \u539f\u5b50\u64cd\u4f5c\u8bed\u4e49
        \n \u2193
        \n\u7f16\u8bd1\u5668\u6839\u636e\u76ee\u6807\u67b6\u6784\u751f\u6210\u5b9e\u73b0
        \n \u2193
        \nCPU \u6307\u4ee4\u3001\u7f13\u5b58\u4e00\u81f4\u6027\u673a\u5236\u6216\u8fd0\u884c\u5e93
        \n \u2193
        \n\u5b8c\u6210\u6ee1\u8db3\u6807\u51c6\u8981\u6c42\u7684\u539f\u5b50\u64cd\u4f5c<\/p>\n

        \u53ef\u4ee5\u901a\u8fc7\u7f16\u8bd1\u5668\u751f\u6210\u7684\u6c47\u7f16\u4ee3\u7801\u89c2\u5bdf\u5177\u4f53\u5b9e\u73b0，\u4f46\u4e0d\u80fd\u5c06\u67d0\u4e2a\u5e73\u53f0\u7684\u5b9e\u73b0\u65b9\u5f0f\u76f4\u63a5\u5f53\u4f5c C++ \u6807\u51c6\u4fdd\u8bc1\u3002<\/p>\n

        \u53c2\u8003：Intel\u00ae 64 and IA-32 \u67b6\u6784\u8f6f\u4ef6\u5f00\u53d1\u624b\u518c\u3001std::atomic \u53c2\u8003\u6587\u6863\u3002<\/p>\n

        std::atomic \u63d0\u4f9b\u7edf\u4e00\u7684\u8bed\u8a00\u7ea7\u8bed\u4e49，\u4f46\u65e0\u9501\u6027\u3001\u6267\u884c\u6210\u672c\u548c\u5177\u4f53\u6307\u4ee4\u90fd\u9700\u8981\u7ed3\u5408\u76ee\u6807\u5e73\u53f0\u5224\u65ad\u3002<\/p>\n

        \u4e09\u3001C++ \u5185\u5b58\u6a21\u578b<\/h3>\n

        3.1 Sequenced-Before：\u5355\u7ebf\u7a0b\u5185\u7684\u5148\u540e\u5173\u7cfb<\/h4>\n

        \u5728\u540c\u4e00\u4e2a\u7ebf\u7a0b\u4e2d，\u5982\u679c\u64cd\u4f5c A \u6309\u7167 C++ \u62bd\u8c61\u673a\u7684\u6267\u884c\u89c4\u5219\u5148\u4e8e\u64cd\u4f5c B，\u90a3\u4e48\u53ef\u4ee5\u5efa\u7acb\u76f8\u5e94\u7684 Sequenced-Before \u5173\u7cfb\u3002<\/p>\n

        \u4f8b\u5982：<\/p>\n

        int<\/span> a =<\/span> 10<\/span>;<\/span>
        \nint<\/span> b =<\/span> a +<\/span> 5<\/span>;<\/span><\/p>\n

        \u8fd9\u91cc\u8bfb\u53d6 a \u5e76\u8ba1\u7b97 b \u7684\u8fc7\u7a0b\u5177\u6709\u7a0b\u5e8f\u6240\u8981\u6c42\u7684\u5148\u540e\u5173\u7cfb\u3002<\/p>\n

        \u4f46\u9700\u8981\u6ce8\u610f，\u6e90\u4ee3\u7801\u7684\u4e66\u5199\u987a\u5e8f\u5e76\u4e0d\u610f\u5473\u7740\u673a\u5668\u6307\u4ee4\u7edd\u5bf9\u4e0d\u80fd\u91cd\u6392\u3002\u7f16\u8bd1\u5668\u548c CPU \u53ef\u4ee5\u8fdb\u884c\u4f18\u5316，\u53ea\u8981\u6700\u7ec8\u884c\u4e3a\u6ee1\u8db3\u8bed\u8a00\u89c4\u5b9a\u7684\u8bed\u4e49\u3002<\/p>\n

        3.2 Synchronizes-With：\u8de8\u7ebf\u7a0b\u540c\u6b65\u5173\u7cfb<\/h4>\n

        \u5047\u8bbe\u7ebf\u7a0b A \u5199\u5165\u6570\u636e，\u7136\u540e\u901a\u8fc7 Release \u64cd\u4f5c\u53d1\u5e03\u72b6\u6001；\u7ebf\u7a0b B \u901a\u8fc7 Acquire \u64cd\u4f5c\u8bfb\u53d6\u5230\u4e86\u5bf9\u5e94\u7684\u53d1\u5e03\u503c\u3002<\/p>\n

        \u6b64\u65f6\u53ef\u4ee5\u5efa\u7acb\u8de8\u7ebf\u7a0b\u540c\u6b65\u5173\u7cfb\u3002<\/p>\n

        #mermaid-svg-xGYsiv9NaVkX0JNJ{font-family:\\”trebuchet ms\\”,verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-xGYsiv9NaVkX0JNJ .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-xGYsiv9NaVkX0JNJ .error-icon{fill:#552222;}#mermaid-svg-xGYsiv9NaVkX0JNJ .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-xGYsiv9NaVkX0JNJ .marker{fill:#333333;stroke:#333333;}#mermaid-svg-xGYsiv9NaVkX0JNJ .marker.cross{stroke:#333333;}#mermaid-svg-xGYsiv9NaVkX0JNJ svg{font-family:\\”trebuchet ms\\”,verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-xGYsiv9NaVkX0JNJ p{margin:0;}#mermaid-svg-xGYsiv9NaVkX0JNJ .label{font-family:\\”trebuchet ms\\”,verdana,arial,sans-serif;color:#333;}#mermaid-svg-xGYsiv9NaVkX0JNJ .cluster-label text{fill:#333;}#mermaid-svg-xGYsiv9NaVkX0JNJ .cluster-label span{color:#333;}#mermaid-svg-xGYsiv9NaVkX0JNJ .cluster-label span p{background-color:transparent;}#mermaid-svg-xGYsiv9NaVkX0JNJ .label text,#mermaid-svg-xGYsiv9NaVkX0JNJ span{fill:#333;color:#333;}#mermaid-svg-xGYsiv9NaVkX0JNJ .node rect,#mermaid-svg-xGYsiv9NaVkX0JNJ .node circle,#mermaid-svg-xGYsiv9NaVkX0JNJ .node ellipse,#mermaid-svg-xGYsiv9NaVkX0JNJ .node polygon,#mermaid-svg-xGYsiv9NaVkX0JNJ .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-xGYsiv9NaVkX0JNJ .rough-node .label text,#mermaid-svg-xGYsiv9NaVkX0JNJ .node .label text,#mermaid-svg-xGYsiv9NaVkX0JNJ .image-shape .label,#mermaid-svg-xGYsiv9NaVkX0JNJ .icon-shape .label{text-anchor:middle;}#mermaid-svg-xGYsiv9NaVkX0JNJ .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-xGYsiv9NaVkX0JNJ .rough-node .label,#mermaid-svg-xGYsiv9NaVkX0JNJ .node .label,#mermaid-svg-xGYsiv9NaVkX0JNJ .image-shape .label,#mermaid-svg-xGYsiv9NaVkX0JNJ .icon-shape .label{text-align:center;}#mermaid-svg-xGYsiv9NaVkX0JNJ .node.clickable{cursor:pointer;}#mermaid-svg-xGYsiv9NaVkX0JNJ .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-xGYsiv9NaVkX0JNJ .arrowheadPath{fill:#333333;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-xGYsiv9NaVkX0JNJ .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-xGYsiv9NaVkX0JNJ .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-xGYsiv9NaVkX0JNJ .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-xGYsiv9NaVkX0JNJ .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-xGYsiv9NaVkX0JNJ .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-xGYsiv9NaVkX0JNJ .cluster text{fill:#333;}#mermaid-svg-xGYsiv9NaVkX0JNJ .cluster span{color:#333;}#mermaid-svg-xGYsiv9NaVkX0JNJ div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:\\”trebuchet ms\\”,verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-xGYsiv9NaVkX0JNJ .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-xGYsiv9NaVkX0JNJ 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.data>*{fill:#e0f2fe!important;stroke:#0284c7!important;stroke-width:2px!important;color:#0f172a!important;}#mermaid-svg-xGYsiv9NaVkX0JNJ .data span{fill:#e0f2fe!important;stroke:#0284c7!important;stroke-width:2px!important;color:#0f172a!important;}#mermaid-svg-xGYsiv9NaVkX0JNJ .data tspan{fill:#0f172a!important;}#mermaid-svg-xGYsiv9NaVkX0JNJ .atomic>*{fill:#fef3c7!important;stroke:#d97706!important;stroke-width:2px!important;color:#0f172a!important;}#mermaid-svg-xGYsiv9NaVkX0JNJ .atomic span{fill:#fef3c7!important;stroke:#d97706!important;stroke-width:2px!important;color:#0f172a!important;}#mermaid-svg-xGYsiv9NaVkX0JNJ .atomic tspan{fill:#0f172a!important;}<\/p>\n

        <\/p>\n

        \u7ebf\u7a0b B<\/p>\n

        <\/span><\/p>\n

        <\/p>\n

        \u7ebf\u7a0b A<\/p>\n

        <\/span><\/p>\n

        <\/span><\/p>\n

        <\/span><\/p>\n

        <\/p>\n

        Synchronizes-Withrelease \u2192 acquire<\/p>\n

        <\/span><\/p>\n

        <\/p>\n

        \u5199\u5165\u666e\u901a\u6570\u636e<\/p>\n

        <\/span><\/p>\n

        <\/p>\n

        atomic.store(release)<\/p>\n

        <\/span><\/p>\n

        <\/p>\n

        atomic.load(acquire)<\/p>\n

        <\/span><\/p>\n

        <\/p>\n

        \u8bfb\u53d6\u666e\u901a\u6570\u636e<\/p>\n

        <\/span><\/p>\n

        \u9700\u8981\u5f3a\u8c03：Release \u548c Acquire \u5e76\u4e0d\u662f\u53ea\u8981\u540c\u65f6\u51fa\u73b0\u5c31\u4f1a\u81ea\u52a8\u540c\u6b65\u3002<\/p>\n

        \u901a\u5e38\u9700\u8981 Acquire \u64cd\u4f5c\u8bfb\u53d6\u5230\u5bf9\u5e94 Release \u64cd\u4f5c\u6240\u5199\u5165\u7684\u503c，\u6216\u8005\u6ee1\u8db3\u6807\u51c6\u89c4\u5b9a\u7684 Release Sequence \u7b49\u6761\u4ef6\u3002<\/p>\n

        3.3 Happens-Before：\u5224\u65ad\u6570\u636e\u7ade\u4e89\u7684\u5173\u952e<\/h4>\n

        Happens-Before \u662f C++ \u5e76\u53d1\u6b63\u786e\u6027\u7684\u6838\u5fc3\u5173\u7cfb\u4e4b\u4e00\u3002<\/p>\n

        \u5b83\u53ef\u4ee5\u7531\u540c\u4e00\u7ebf\u7a0b\u4e2d\u7684 Sequenced-Before \u5173\u7cfb，\u4ee5\u53ca\u8de8\u7ebf\u7a0b\u540c\u6b65\u5173\u7cfb\u7b49\u4f20\u9012\u89c4\u5219\u5efa\u7acb\u3002<\/p>\n

        \u4f8b\u5982：<\/p>\n

        \u7ebf\u7a0b A：<\/p>\n

        \u5199\u5165 data
        \n \u2502
        \n \u25bc
        \nstore(flag, release)
        \n \u2502
        \n \u2502 Synchronizes-With
        \n \u25bc
        \n\u7ebf\u7a0b B：<\/p>\n

        load(flag, acquire)
        \n \u2502
        \n \u25bc
        \n\u8bfb\u53d6 data<\/p>\n

        \u5982\u679c Acquire \u8bfb\u53d6\u5230\u4e86\u76f8\u5e94\u7684 Release \u5199\u5165，\u5c31\u53ef\u4ee5\u901a\u8fc7\u4f20\u9012\u5173\u7cfb\u5efa\u7acb：<\/p>\n

        \u5199\u5165 data
        \n Happens-Before
        \n\u8bfb\u53d6 data<\/p>\n

        \u56e0\u6b64，\u5728\u6ee1\u8db3\u5176\u4ed6\u8bbf\u95ee\u7ea6\u675f\u7684\u524d\u63d0\u4e0b，\u7ebf\u7a0b B \u53ef\u4ee5\u5b89\u5168\u8bfb\u53d6\u7ebf\u7a0b A \u53d1\u5e03\u7684\u6570\u636e\u3002<\/p>\n

        3.4 Modification Order：\u6bcf\u4e2a\u539f\u5b50\u5bf9\u8c61\u90fd\u6709\u81ea\u5df1\u7684\u4fee\u6539\u987a\u5e8f<\/h4>\n

        C++ \u89c4\u5b9a，\u5bf9\u540c\u4e00\u4e2a\u539f\u5b50\u5bf9\u8c61\u7684\u4fee\u6539\u5b58\u5728\u8be5\u5bf9\u8c61\u7279\u6709\u7684 Modification Order\u3002<\/p>\n

        \u4f8b\u5982：<\/p>\n

        std::<\/span>atomic<<\/span>int<\/span>><\/span> x{<\/span>0<\/span>}<\/span>;<\/span><\/p>\n

        \u5bf9 x \u7684\u539f\u5b50\u4fee\u6539\u5fc5\u987b\u6ee1\u8db3\u8be5\u5bf9\u8c61\u7684\u4fee\u6539\u987a\u5e8f\u53ca\u4e00\u81f4\u6027\u8981\u6c42\u3002<\/p>\n

        \u4f46\u662f，\u4e0d\u540c\u539f\u5b50\u5bf9\u8c61\u5404\u81ea\u7684\u4fee\u6539\u987a\u5e8f，\u5e76\u4e0d\u4f1a\u81ea\u52a8\u7ec4\u6210\u4e00\u4e2a\u8986\u76d6\u6240\u6709\u5185\u5b58\u8bbf\u95ee\u7684\u5168\u5c40\u987a\u5e8f\u3002<\/p>\n

        \u8fd9\u4e5f\u662f\u4e3a\u4ec0\u4e48\u4e0d\u80fd\u901a\u8fc7\u201c\u6240\u6709\u53d8\u91cf\u90fd\u662f\u539f\u5b50\u7684\u201d\u5c31\u76f4\u63a5\u63a8\u5bfc\u51fa\u590d\u6742\u7a0b\u5e8f\u7684\u6574\u4f53\u72b6\u6001\u4e00\u5b9a\u4e00\u81f4\u3002<\/p>\n

        3.5 Data Race \u4e3a\u4ec0\u4e48\u4f1a\u5bfc\u81f4\u672a\u5b9a\u4e49\u884c\u4e3a？<\/h4>\n

        \u4e24\u4e2a\u7ebf\u7a0b\u5bf9\u540c\u4e00\u5185\u5b58\u4f4d\u7f6e\u8fdb\u884c\u51b2\u7a81\u8bbf\u95ee\u65f6，\u5982\u679c\u81f3\u5c11\u4e00\u4e2a\u8bbf\u95ee\u4e0d\u662f\u539f\u5b50\u64cd\u4f5c，\u5e76\u4e14\u4e8c\u8005\u4e4b\u95f4\u6ca1\u6709\u6240\u9700\u7684 Happens-Before \u5173\u7cfb，\u5c31\u53ef\u80fd\u6784\u6210\u6570\u636e\u7ade\u4e89\u3002<\/p>\n

        \u4f8b\u5982：<\/p>\n

        int<\/span> data =<\/span> 0<\/span>;<\/span>
        \nstd::<\/span>atomic<<\/span>bool<\/span>><\/span> ready{<\/span>false<\/span>}<\/span>;<\/span><\/p>\n

        \/\/ \u7ebf\u7a0b A<\/span>
        \ndata =<\/span> 42<\/span>;<\/span>
        \nready.<\/span>store<\/span>(<\/span>true<\/span>,<\/span> std::<\/span>memory_order_relaxed)<\/span>;<\/span><\/p>\n

        \/\/ \u7ebf\u7a0b B<\/span>
        \nif<\/span> (<\/span>ready.<\/span>load<\/span>(<\/span>std::<\/span>memory_order_relaxed)<\/span>)<\/span> {<\/span>
        \n std::<\/span>cout <<<\/span> data <<<\/span> '\\\\n'<\/span>;<\/span>
        \n}<\/span><\/p>\n

        \u8fd9\u91cc ready \u7684\u8bbf\u95ee\u672c\u8eab\u6ca1\u6709\u6570\u636e\u7ade\u4e89，\u4f46 Relaxed \u4e0d\u4f1a\u5efa\u7acb\u5fc5\u8981\u7684\u8de8\u7ebf\u7a0b\u540c\u6b65\u5173\u7cfb\u3002\u56e0\u6b64，\u7ebf\u7a0b A \u5bf9 data \u7684\u5199\u5165\u4e0e\u7ebf\u7a0b B \u5bf9 data \u7684\u8bfb\u53d6\u4e4b\u95f4\u6ca1\u6709\u6240\u9700\u7684 Happens-Before \u5173\u7cfb\u3002<\/p>\n

        \u8fd9\u6bb5\u4ee3\u7801\u5b58\u5728\u6570\u636e\u7ade\u4e89，\u884c\u4e3a\u672a\u5b9a\u4e49\u3002<\/p>\n

        \u539f\u5b50\u53d8\u91cf\u6ca1\u6709\u6570\u636e\u7ade\u4e89，\u4e0d\u4ee3\u8868\u56f4\u7ed5\u5b83\u6784\u5efa\u7684\u6574\u4e2a\u7a0b\u5e8f\u6ca1\u6709\u6570\u636e\u7ade\u4e89\u3002<\/p>\n

        \u56db\u3001Memory Order：\u516d\u79cd\u5185\u5b58\u5e8f\u7684\u539f\u7406\u4e0e\u9009\u62e9<\/h3>\n

        std::memory_order \u7528\u6765\u89c4\u5b9a\u539f\u5b50\u64cd\u4f5c\u5bf9\u5176\u4ed6\u5185\u5b58\u8bbf\u95ee\u7684\u6392\u5e8f\u548c\u540c\u6b65\u7ea6\u675f\u3002<\/p>\n

        C++11 \u5f15\u5165\u4e86\u516d\u79cd\u5185\u5b58\u5e8f：<\/p>\n

          \n
        • memory_order_relaxed<\/li>\n
        • memory_order_consume<\/li>\n
        • memory_order_acquire<\/li>\n
        • memory_order_release<\/li>\n
        • memory_order_acq_rel<\/li>\n
        • memory_order_seq_cst<\/li>\n<\/ul>\n

          \u5b9e\u9645\u5de5\u7a0b\u4e2d\u6700\u5e38\u4f7f\u7528\u7684\u662f Relaxed\u3001Acquire\u3001Release\u3001Acquire-Release \u548c Sequentially Consistent\u3002<\/p>\n

          4.1 \u516d\u79cd\u5185\u5b58\u5e8f<\/h4>\n\n\u5185\u5b58\u5e8f\u4fdd\u8bc1\u7528\u9014<\/tr>\n\n\n\n\n\n\n\n
          relaxed<\/td>\n\u539f\u5b50\u6027\u53ca\u539f\u5b50\u5bf9\u8c61\u81ea\u8eab\u7684\u4fee\u6539\u987a\u5e8f\u7ea6\u675f，\u4e0d\u5efa\u7acb\u540c\u6b65\u5173\u7cfb<\/td>\n\u72ec\u7acb\u8ba1\u6570\u5668\u3001\u7edf\u8ba1\u503c<\/td>\n<\/tr>\n
          consume<\/td>\n\u57fa\u4e8e\u4f9d\u8d56\u5173\u7cfb\u7684\u6392\u5e8f\u8bed\u4e49<\/td>\n\u4e00\u822c\u5e94\u7528\u901a\u5e38\u4e0d\u4e3b\u52a8\u4f7f\u7528<\/td>\n<\/tr>\n
          acquire<\/td>\n\u4e3a\u540e\u7eed\u5185\u5b58\u8bbf\u95ee\u63d0\u4f9b Acquire \u6392\u5e8f\u7ea6\u675f<\/td>\n\u8bfb\u53d6\u5df2\u53d1\u5e03\u7684\u6570\u636e<\/td>\n<\/tr>\n
          release<\/td>\n\u4e3a\u4e4b\u524d\u7684\u5185\u5b58\u8bbf\u95ee\u63d0\u4f9b Release \u6392\u5e8f\u7ea6\u675f<\/td>\n\u53d1\u5e03\u5df2\u7ecf\u51c6\u5907\u597d\u7684\u6570\u636e<\/td>\n<\/tr>\n
          acq_rel<\/td>\n\u540c\u65f6\u5177\u5907 Acquire \u548c Release \u8bed\u4e49<\/td>\n\u9700\u8981\u53cc\u5411\u6392\u5e8f\u8bed\u4e49\u7684\u8bfb\u2014\u6539\u2014\u5199\u64cd\u4f5c<\/td>\n<\/tr>\n
          seq_cst<\/td>\nAcquire\/Release \u8bed\u4e49\u53ca\u53c2\u4e0e\u987a\u5e8f\u4e00\u81f4\u6027\u6392\u5e8f\u7684\u5168\u5e8f\u7ea6\u675f<\/td>\n\u9ed8\u8ba4\u9009\u62e9\u3001\u9700\u8981\u66f4\u76f4\u89c2\u5168\u5c40\u6392\u5e8f\u7684\u573a\u666f<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

          4.2 Relaxed：\u53ea\u9700\u8981\u539f\u5b50\u6027\u65f6\u4f7f\u7528<\/h4>\n

          \u4f8b\u5982：<\/p>\n

          std::<\/span>atomic<<\/span>int<\/span>><\/span> request_count{<\/span>0<\/span>}<\/span>;<\/span><\/p>\n

          void<\/span> record_request<\/span>(<\/span>)<\/span> {<\/span>
          \n request_count.<\/span>fetch_add<\/span>(<\/span>1<\/span>,<\/span> std::<\/span>memory_order_relaxed)<\/span>;<\/span>
          \n}<\/span><\/p>\n

          \u5047\u8bbe\u8fd9\u4e2a\u53d8\u91cf\u53ea\u7528\u4e8e\u7edf\u8ba1\u8bf7\u6c42\u6570\u91cf，\u4e0d\u8d1f\u8d23\u53d1\u5e03\u5176\u4ed6\u5171\u4eab\u6570\u636e，\u90a3\u4e48 Relaxed \u901a\u5e38\u5df2\u7ecf\u8db3\u591f\u3002<\/p>\n

          \u5b83\u4ecd\u7136\u4fdd\u8bc1：<\/p>\n

        • \u6bcf\u6b21\u539f\u5b50\u66f4\u65b0\u90fd\u662f\u539f\u5b50\u7684\u3002<\/li>\n
        • \u540c\u4e00\u4e2a\u539f\u5b50\u5bf9\u8c61\u7684\u4fee\u6539\u9075\u5faa\u5176\u4fee\u6539\u987a\u5e8f\u89c4\u5219\u3002<\/li>\n
        • \u591a\u7ebf\u7a0b\u4e0d\u4f1a\u56e0\u4e3a\u5bf9\u8fd9\u4e2a\u539f\u5b50\u53d8\u91cf\u7684\u8bbf\u95ee\u800c\u4ea7\u751f\u666e\u901a\u7684\u6570\u636e\u7ade\u4e89\u3002<\/li>\n

          \u4f46\u5b83\u4e0d\u4f1a\u901a\u8fc7\u8fd9\u6b21\u64cd\u4f5c\u5efa\u7acb\u8de8\u7ebf\u7a0b\u540c\u6b65，\u4e5f\u4e0d\u4f1a\u81ea\u52a8\u4e3a\u5176\u4ed6\u666e\u901a\u5185\u5b58\u8bbf\u95ee\u5efa\u7acb\u6392\u5e8f\u5173\u7cfb\u3002 Relaxed \u7684\u9650\u5236\u662f：\u4e0d\u80fd\u4ec5\u51ed Relaxed \u64cd\u4f5c\u6765\u53d1\u5e03\u548c\u4fdd\u62a4\u76f8\u5173\u7684\u975e\u539f\u5b50\u5171\u4eab\u6570\u636e\u3002<\/p>\n

          4.3 Release：\u53d1\u5e03\u4e4b\u524d\u5b8c\u6210\u7684\u5de5\u4f5c<\/h4>\n

          \u4f8b\u5982：<\/p>\n

          data =<\/span> 42<\/span>;<\/span>
          \nready.<\/span>store<\/span>(<\/span>true<\/span>,<\/span> std::<\/span>memory_order_release)<\/span>;<\/span><\/p>\n

          Release \u64cd\u4f5c\u9002\u5408\u53d1\u5e03\u5df2\u7ecf\u51c6\u5907\u597d\u7684\u6570\u636e\u3002<\/p>\n

          \u5728\u76f8\u5e94\u7684\u62bd\u8c61\u8bed\u4e49\u4e0b，\u4e0d\u80fd\u628a Release \u4e4b\u524d\u7684\u5185\u5b58\u8bbf\u95ee\u968f\u610f\u8c03\u6574\u5230\u5b83\u4e4b\u540e，\u4ece\u800c\u7834\u574f\u6807\u51c6\u89c4\u5b9a\u7684\u6392\u5e8f\u5173\u7cfb\u3002<\/p>\n

          \u4f46 Release \u672c\u8eab\u4e0d\u4f1a\u963b\u6b62\u5176\u4ed6\u7ebf\u7a0b\u8bfb\u53d6\u6570\u636e\u3002\u5b83\u9700\u8981\u4e0e\u7b26\u5408\u6761\u4ef6\u7684 Acquire \u64cd\u4f5c\u914d\u5408，\u624d\u80fd\u5efa\u7acb\u8de8\u7ebf\u7a0b\u540c\u6b65\u3002<\/p>\n

          4.4 Acquire：\u83b7\u53d6\u5df2\u53d1\u5e03\u7684\u6570\u636e<\/h4>\n

          \u4f8b\u5982：<\/p>\n

          if<\/span> (<\/span>ready.<\/span>load<\/span>(<\/span>std::<\/span>memory_order_acquire)<\/span>)<\/span> {<\/span>
          \n use<\/span>(<\/span>data)<\/span>;<\/span>
          \n}<\/span><\/p>\n

          \u5982\u679c\u8fd9\u6b21 Acquire \u8bfb\u53d6\u5230\u4e86\u76f8\u5e94 Release \u53d1\u5e03\u7684\u503c，\u90a3\u4e48\u4e4b\u524d\u7684\u5199\u5165\u53ef\u4ee5\u901a\u8fc7 Happens-Before \u5173\u7cfb\u5bf9\u5f53\u524d\u7ebf\u7a0b\u5efa\u7acb\u540c\u6b65\u3002<\/p>\n

          Acquire \u7684\u91cd\u70b9\u662f：\u5b83\u4e3a\u540e\u7eed\u5185\u5b58\u8bbf\u95ee\u5efa\u7acb\u76f8\u5e94\u7684\u6392\u5e8f\u7ea6\u675f\u3002<\/p>\n

          \u5b83\u4e0d\u662f\u7b80\u5355\u5730\u8981\u6c42 CPU \u201c\u7acb\u5373\u5237\u65b0\u6240\u6709\u7f13\u5b58\u201d，\u4e5f\u4e0d\u662f\u4e00\u4e2a\u65e0\u6761\u4ef6\u7684\u5168\u5c40\u5185\u5b58\u5c4f\u969c\u3002<\/p>\n

          4.5 Acquire-Release：\u7528\u4e8e\u8bfb\u2014\u6539\u2014\u5199\u64cd\u4f5c<\/h4>\n

          memory_order_acq_rel \u540c\u65f6\u5177\u6709 Acquire \u548c Release \u8bed\u4e49，\u4e3b\u8981\u7528\u4e8e\u539f\u5b50\u8bfb\u2014\u6539\u2014\u5199\u64cd\u4f5c\u3002<\/p>\n

          \u4f8b\u5982：<\/p>\n

          std::<\/span>atomic<<\/span>int<\/span>><\/span> state{<\/span>0<\/span>}<\/span>;<\/span><\/p>\n

          int<\/span> old =<\/span> state.<\/span>exchange<\/span>(<\/span>1<\/span>,<\/span> std::<\/span>memory_order_acq_rel)<\/span>;<\/span><\/p>\n

          \u8fd9\u91cc\u7684\u4ea4\u6362\u64cd\u4f5c\u65e2\u8bfb\u53d6\u65e7\u72b6\u6001，\u53c8\u53d1\u5e03\u65b0\u72b6\u6001，\u56e0\u6b64\u53ef\u4ee5\u540c\u65f6\u9700\u8981 Acquire \u548c Release \u8bed\u4e49\u3002<\/p>\n

          \u6ce8\u610f，acq_rel \u4e0d\u80fd\u7528\u4e8e\u666e\u901a load() \u6216 store()\u3002<\/p>\n

          4.6 Sequentially Consistent：\u9ed8\u8ba4\u5185\u5b58\u5e8f<\/h4>\n

          \u5982\u679c\u4e0d\u663e\u5f0f\u6307\u5b9a\u5185\u5b58\u5e8f，\u8bb8\u591a std::atomic \u64cd\u4f5c\u9ed8\u8ba4\u4f7f\u7528 memory_order_seq_cst\u3002<\/p>\n

          memory_order_seq_cst\u4e3a\u53c2\u4e0e\u987a\u5e8f\u4e00\u81f4\u6027\u6392\u5e8f\u7684\u539f\u5b50\u64cd\u4f5c\u63d0\u4f9b\u4e00\u4e2a\u6ee1\u8db3\u6807\u51c6\u7ea6\u675f\u7684\u5168\u5e8f，\u5e76\u5305\u542b\u76f8\u5e94\u7684 Acquire\/Release \u8bed\u4e49\u3002<\/p>\n

          \u5982\u679c\u5176\u4ed6\u8bbf\u95ee\u4f7f\u7528\u4e86 Relaxed \u7b49\u975e Seq-Cst \u64cd\u4f5c，\u4e0d\u80fd\u4ec5\u51ed\u67d0\u4e2a\u64cd\u4f5c\u4f7f\u7528 Seq-Cst \u5c31\u63a8\u65ad\u6240\u6709\u7ebf\u7a0b\u90fd\u80fd\u89c2\u5bdf\u5230\u5b8c\u5168\u4e00\u81f4\u7684\u5168\u5c40\u6267\u884c\u987a\u5e8f\u3002<\/p>\n

          \u53e6\u5916，Seq-Cst \u5e76\u4e0d\u5fc5\u7136\u6bd4\u5176\u4ed6\u5185\u5b58\u5e8f\u6162\u3002\u4e0d\u540c\u67b6\u6784\u3001\u4e0d\u540c\u64cd\u4f5c\u53ef\u80fd\u751f\u6210\u76f8\u540c\u6216\u6210\u672c\u63a5\u8fd1\u7684\u6307\u4ee4\u5e8f\u5217\u3002<\/p>\n

          4.7 Consume：\u4e86\u89e3\u5373\u53ef，\u901a\u5e38\u4f18\u5148\u4f7f\u7528 Acquire<\/h4>\n

          memory_order_consume \u7684\u8bed\u4e49\u4e0e\u4f9d\u8d56\u5173\u7cfb\u6709\u5173，\u4f46\u5176\u5b9e\u73b0\u548c\u4f7f\u7528\u5177\u6709\u590d\u6742\u6027\u3002<\/p>\n

          \u4e00\u822c\u4e1a\u52a1\u4ee3\u7801\u6ca1\u6709\u5fc5\u8981\u4e3a\u4e86\u6f5c\u5728\u7684\u6027\u80fd\u6536\u76ca\u800c\u4e3b\u52a8\u91c7\u7528\u5b83\u3002\u9664\u975e\u5bf9\u5177\u4f53\u7f16\u8bd1\u5668\u3001\u5e73\u53f0\u548c\u4f9d\u8d56\u5173\u7cfb\u6709\u6df1\u5165\u7406\u89e3，\u5e76\u7ecf\u8fc7\u5b9e\u6d4b\u9a8c\u8bc1，\u5426\u5219\u4f18\u5148\u4f7f\u7528 Acquire \u66f4\u5bb9\u6613\u7ef4\u62a4\u3002<\/p>\n

          4.8 \u4f7f\u7528\u5185\u5b58\u5e8f\u65f6\u7684\u57fa\u672c\u7ea6\u675f<\/h4>\n

          \u9700\u8981\u7279\u522b\u6ce8\u610f：<\/p>\n

            \n
          • load() \u4e0d\u80fd\u4f7f\u7528 memory_order_release \u6216 memory_order_acq_rel\u3002<\/li>\n
          • store() \u4e0d\u80fd\u4f7f\u7528 memory_order_acquire\u3001memory_order_consume \u6216 memory_order_acq_rel\u3002<\/li>\n
          • compare_exchange \u7684\u5931\u8d25\u5185\u5b58\u5e8f\u4e0d\u80fd\u4f7f\u7528 Release \u6216 Acquire-Release，\u4e5f\u4e0d\u80fd\u5f3a\u4e8e\u6210\u529f\u5185\u5b58\u5e8f\u3002<\/li>\n
          • \u4f7f\u7528 Relaxed \u4e0d\u4f1a\u81ea\u52a8\u6d88\u9664\u666e\u901a\u5171\u4eab\u6570\u636e\u7684\u7ade\u4e89\u3002<\/li>\n<\/ul>\n

            \u5148\u5efa\u7acb\u6b63\u786e\u7684\u540c\u6b65\u5173\u7cfb，\u518d\u8003\u8651\u964d\u4f4e\u5185\u5b58\u5e8f\u3002\u4e0d\u8981\u628a\u4f18\u5316 Memory Order \u5f53\u4f5c\u5e76\u53d1\u8bbe\u8ba1\u7684\u7b2c\u4e00\u6b65\u3002<\/p>\n

            \u4e94\u3001Release-Acquire ：\u751f\u4ea7\u8005\u2014\u6d88\u8d39\u8005\u7684\u6570\u636e\u53d1\u5e03<\/h3>\n

            \u5047\u8bbe\u751f\u4ea7\u8005\u7ebf\u7a0b\u8d1f\u8d23\u751f\u6210\u6570\u636e，\u6d88\u8d39\u8005\u7ebf\u7a0b\u9700\u8981\u7b49\u5f85\u6570\u636e\u51c6\u5907\u5b8c\u6210\u540e\u518d\u8bfb\u53d6\u3002<\/p>\n

            5.1 \u4f7f\u7528 Release-Acquire \u53d1\u5e03\u6570\u636e<\/h4>\n

            #<\/span>include<\/span> <atomic><\/span><\/span>
            \n#<\/span>include<\/span> <iostream><\/span><\/span>
            \n#<\/span>include<\/span> <thread><\/span><\/span><\/p>\n

            int<\/span> shared_data =<\/span> 0<\/span>;<\/span>
            \nstd::<\/span>atomic<<\/span>bool<\/span>><\/span> data_ready{<\/span>false<\/span>}<\/span>;<\/span><\/p>\n

            void<\/span> producer<\/span>(<\/span>)<\/span> {<\/span>
            \n shared_data =<\/span> 42<\/span>;<\/span><\/p>\n

            data_ready.<\/span>store<\/span>(<\/span>
            \n true<\/span>,<\/span>
            \n std::<\/span>memory_order_release
            \n )<\/span>;<\/span>
            \n}<\/span><\/p>\n

            void<\/span> consumer<\/span>(<\/span>)<\/span> {<\/span>
            \n while<\/span> (<\/span>!<\/span>data_ready.<\/span>load<\/span>(<\/span>
            \n std::<\/span>memory_order_acquire
            \n )<\/span>)<\/span> {<\/span>
            \n std::<\/span>this_thread::<\/span>yield<\/span>(<\/span>)<\/span>;<\/span>
            \n }<\/span><\/p>\n

            std::<\/span>cout <<<\/span> shared_data <<<\/span> '\\\\n'<\/span>;<\/span>
            \n}<\/span><\/p>\n

            int<\/span> main<\/span>(<\/span>)<\/span> {<\/span>
            \n std::<\/span>thread t1<\/span>(<\/span>producer)<\/span>;<\/span>
            \n std::<\/span>thread t2<\/span>(<\/span>consumer)<\/span>;<\/span><\/p>\n

            t1.<\/span>join<\/span>(<\/span>)<\/span>;<\/span>
            \n t2.<\/span>join<\/span>(<\/span>)<\/span>;<\/span>
            \n}<\/span><\/p>\n

            \u8fd9\u91cc\u7684 shared_data \u672c\u8eab\u4e0d\u662f\u539f\u5b50\u53d8\u91cf，\u4f46\u5728\u8fd9\u4e2a\u5355\u6b21\u53d1\u5e03\u793a\u4f8b\u4e2d，\u5b83\u4ecd\u7136\u53ef\u4ee5\u5b89\u5168\u4f7f\u7528\u3002<\/p>\n

            \u539f\u56e0\u5982\u4e0b：<\/p>\n

          • \u751f\u4ea7\u8005\u5148\u5199\u5165 shared_data\u3002<\/li>\n
          • \u751f\u4ea7\u8005\u901a\u8fc7 Release \u5199\u5165 data_ready = true\u3002<\/li>\n
          • \u6d88\u8d39\u8005\u7684 Acquire \u8bfb\u53d6\u5230\u4e86\u8fd9\u4e2a Release \u5199\u5165\u7684\u503c\u3002<\/li>\n
          • \u4e24\u6b21\u64cd\u4f5c\u5efa\u7acb Synchronizes-With \u5173\u7cfb\u3002<\/li>\n
          • \u751f\u4ea7\u8005\u5bf9 shared_data \u7684\u5199\u5165 Happens-Before \u6d88\u8d39\u8005\u5bf9\u5b83\u7684\u8bfb\u53d6\u3002<\/li>\n

            \u56e0\u6b64，\u6d88\u8d39\u8005\u8bfb\u53d6\u5230\u7684\u6570\u636e\u662f 42\u3002<\/p>\n

            \u8fd9\u4e2a\u793a\u4f8b\u7684\u524d\u63d0\u662f：\u751f\u4ea7\u8005\u53ea\u5199\u5165\u4e00\u6b21\u6570\u636e，\u6d88\u8d39\u8005\u8bfb\u53d6\u671f\u95f4\u6ca1\u6709\u5176\u4ed6\u7ebf\u7a0b\u518d\u6b21\u4fee\u6539 shared_data\u3002<\/p>\n

            \u5982\u679c\u8981\u53cd\u590d\u590d\u7528\u540c\u4e00\u4efd\u6570\u636e，\u5c31\u9700\u8981\u989d\u5916\u8bbe\u8ba1\u72b6\u6001\u590d\u4f4d\u3001\u751f\u4ea7\u8005\u548c\u6d88\u8d39\u8005\u4e4b\u95f4\u7684\u4ea4\u63a5，\u4ee5\u53ca\u7f13\u51b2\u533a\u751f\u547d\u5468\u671f\u3002<\/p>\n

            5.2 \u4e3a\u4ec0\u4e48\u628a\u4e24\u5904\u5185\u5b58\u5e8f\u6539\u6210 Relaxed \u4f1a\u51fa\u95ee\u9898？<\/h4>\n

            \u5982\u679c\u628a Release \u548c Acquire \u90fd\u66ff\u6362\u6210 Relaxed，data_ready \u4f9d\u7136\u662f\u539f\u5b50\u53d8\u91cf，\u4f46\u5b83\u4e0d\u518d\u901a\u8fc7\u8fd9\u7ec4\u64cd\u4f5c\u5efa\u7acb\u6240\u9700\u7684\u540c\u6b65\u5173\u7cfb\u3002<\/p>\n

            \u751f\u4ea7\u8005\u548c\u6d88\u8d39\u8005\u5bf9\u666e\u901a\u53d8\u91cf shared_data \u7684\u51b2\u7a81\u8bbf\u95ee\u53ef\u80fd\u6784\u6210\u6570\u636e\u7ade\u4e89\u3002<\/p>\n

            5.3 \u4e00\u6b21\u53d1\u5e03\u4e0e\u53cd\u590d\u53d1\u5e03\u7684\u533a\u522b<\/h4>\n

            \u4e0a\u9762\u7684\u793a\u4f8b\u53ea\u6709\u4e00\u6b21\u53d1\u5e03\u3002\u5982\u679c\u6539\u6210：<\/p>\n

            \u751f\u4ea7\u8005：
            \n\u5199\u5165 Buffer A
            \n\u53d1\u5e03 Buffer A
            \n\u518d\u6b21\u5199\u5165 Buffer A<\/p>\n

            \u6d88\u8d39\u8005：
            \n\u8bfb\u53d6 Buffer A<\/p>\n

            \u5373\u4f7f\u53d1\u5e03\u548c\u8bfb\u53d6\u4f7f\u7528\u4e86\u6b63\u786e\u7684 Release-Acquire，\u751f\u4ea7\u8005\u4ecd\u53ef\u80fd\u5728\u6d88\u8d39\u8005\u8bfb\u53d6\u671f\u95f4\u8986\u76d6 Buffer A\u3002<\/p>\n

            \u8fd9\u610f\u5473\u7740 Release-Acquire \u89e3\u51b3\u7684\u662f\u6570\u636e\u53d1\u5e03\u548c\u540c\u6b65\u95ee\u9898，\u800c\u4e0d\u662f\u81ea\u52a8\u89e3\u51b3 Buffer \u7684\u8bfb\u5199\u6240\u6709\u6743\u95ee\u9898\u3002<\/p>\n

            \u5bf9\u4e8e\u56fe\u50cf\u3001\u70b9\u4e91\u6216\u5176\u4ed6\u9ad8\u9891\u6570\u636e，\u901a\u5e38\u8fd8\u9700\u8981\u53cc\u7f13\u51b2\u3001\u73af\u5f62\u7f13\u51b2\u533a\u3001\u6240\u6709\u6743\u8f6c\u79fb\u6216\u5176\u4ed6\u660e\u786e\u7684\u8bfb\u5199\u4ea4\u63a5\u534f\u8bae\u3002<\/p>\n

            \u516d\u3001CAS：\u6784\u5efa\u65e0\u9501\u7b97\u6cd5<\/h3>\n

            CAS \u662f Compare-And-Swap \u7684\u7b80\u79f0，\u5728 C++ \u4e2d\u4e3b\u8981\u901a\u8fc7 compare_exchange_weak() \u548c compare_exchange_strong() \u63d0\u4f9b\u3002<\/p>\n

            6.1 CAS \u7684\u57fa\u672c\u8bed\u4e49<\/h4>\n

            CAS \u53ef\u4ee5\u62bd\u8c61\u4e3a：<\/p>\n

            \u8bfb\u53d6\u5f53\u524d\u539f\u5b50\u503c<\/p>\n

            \u5982\u679c\u5f53\u524d\u503c == expected：
            \n \u539f\u5b50\u5730\u5c06\u503c\u66ff\u6362\u4e3a desired
            \n \u8fd4\u56de true
            \n\u5426\u5219：
            \n \u5c06\u5b9e\u9645\u503c\u5199\u56de expected
            \n \u8fd4\u56de false<\/p>\n

              \n
            • \u5339\u914d\u6210\u529f = \u6761\u4ef6\u6210\u7acb \u2192 \u6267\u884c\u60f3\u8981\u7684\u4fee\u6539，\u628a\u539f\u5b50\u53d8\u91cf\u6362\u6210 desired<\/li>\n
            • \u5339\u914d\u5931\u8d25 = \u6761\u4ef6\u4e0d\u6210\u7acb \u2192 \u522b\u4eba\u5df2\u7ecf\u52a8\u8fc7\u4e86，\u4e0d\u4fee\u6539\u539f\u5b50\u53d8\u91cf，\u8fd4\u56de\u5931\u8d25\u91cd\u8bd5\u3002<\/li>\n<\/ul>\n
            • expected \u662f\u8f93\u5165 + \u8f93\u51fa\u53cc\u5411\u53c2\u6570：\u8c03\u7528\u65f6\u662f\u9884\u671f\u503c；CAS \u5931\u8d25，\u4f1a\u88ab\u91cd\u5199\u6210\u539f\u5b50\u53d8\u91cf\u771f\u5b9e\u503c\u3002<\/li>\n
            • \u6210\u529f：\u6539\u5199\u539f\u5b50\u53d8\u91cf，\u4e0d\u52a8 expected，\u8fd4\u56de true；<\/li>\n
            • \u5931\u8d25：\u4e0d\u52a8\u539f\u5b50\u53d8\u91cf，\u5237\u65b0 expected \u4e3a\u6700\u65b0\u503c，\u8fd4\u56de false\u3002<\/li>\n

              \u8fd9\u4e5f\u662f\u65e0\u9501\u7f16\u7a0b CAS \u5faa\u73af\u7684\u6838\u5fc3\u8303\u5f0f：\u5c40\u90e8\u53d8\u91cf\u4fdd\u5b58\u9884\u671f\u503c，\u4ea4\u7ed9 CAS，\u5931\u8d25\u81ea\u52a8\u5237\u65b0\u5c40\u90e8\u53d8\u91cf，\u5faa\u73af\u91cd\u8bd5\u3002<\/p>\n

              \u6ce8\u610f，\u8fd9\u91cc\u7684\u6bd4\u8f83\u4e0e\u66f4\u65b0\u662f\u4e00\u4e2a\u539f\u5b50\u64cd\u4f5c\u3002<\/p>\n

              6.2 compare_exchange_weak \u4e0e strong \u7684\u533a\u522b<\/h4>\n\n\u63a5\u53e3\u7279\u70b9<\/tr>\n\n\n\n
              compare_exchange_weak()<\/td>\n\u5141\u8bb8\u865a\u5047\u5931\u8d25，\u5373\u4f7f\u6bd4\u8f83\u503c\u76f8\u7b49\u4e5f\u53ef\u80fd\u8fd4\u56de\u5931\u8d25<\/td>\n<\/tr>\n
              compare_exchange_strong()<\/td>\n\u4e0d\u5141\u8bb8\u4ec5\u56e0\u865a\u5047\u5931\u8d25\u800c\u8fd4\u56de\u5931\u8d25<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

              strong \u4ecd\u7136\u53ef\u80fd\u56e0\u4e3a\u5f53\u524d\u503c\u4e0e expected \u4e0d\u76f8\u7b49\u800c\u5931\u8d25\u3002<\/p>\n

              \u5728\u5faa\u73af\u91cd\u8bd5\u7684\u7b97\u6cd5\u4e2d，weak \u901a\u5e38\u5f88\u9002\u5408，\u56e0\u4e3a\u67d0\u4e9b\u5e73\u53f0\u53ef\u4ee5\u66f4\u9ad8\u6548\u5730\u5b9e\u73b0\u5b83\u3002<\/p>\n

              6.3 CAS \u7684\u6b63\u786e\u4f7f\u7528\u65b9\u5f0f：\u539f\u5b50\u6700\u5927\u503c<\/h4>\n

              \u4e0b\u9762\u5b9e\u73b0\u4e00\u4e2a\u7ebf\u7a0b\u5b89\u5168\u7684\u6700\u5927\u503c\u66f4\u65b0\u51fd\u6570\u3002<\/p>\n

              #<\/span>include<\/span> <atomic><\/span><\/span><\/p>\n

              void<\/span> atomic_max<\/span>(<\/span>
              \n std::<\/span>atomic<<\/span>int<\/span>><\/span>&<\/span> target,<\/span>
              \n int<\/span> candidate
              \n)<\/span> {<\/span>
              \n \/\/ \u5148relaxed\u5e8f\u8bfb\u51fa\u5f53\u524dtarget\u7684\u503c<\/span>
              \n int<\/span> current =<\/span> target.<\/span>load<\/span>(<\/span>std::<\/span>memory_order_relaxed)<\/span>;<\/span><\/p>\n

              \/\/ \u5faa\u73af\u6761\u4ef6\u4e24\u4ef6\u4e8b：<\/span>
              \n \/\/ 1. current < candidate：\u624d\u9700\u8981\u66f4\u65b0；\u5982\u679ccurrent\u5df2\u7ecf\u66f4\u5927，\u76f4\u63a5\u9000\u51fa\u5faa\u73af，\u4ec0\u4e48\u90fd\u4e0d\u505a<\/span>
              \n \/\/ 2. CAS\u5931\u8d25：!compare_exchange_weak \u8fd4\u56detrue\u4ee3\u8868CAS\u5931\u8d25，\u7ee7\u7eed\u81ea\u65cb<\/span>
              \n while<\/span> (<\/span>
              \n current <<\/span> candidate &&<\/span>
              \n !<\/span>target.<\/span>compare_exchange_weak<\/span>(<\/span>
              \n current,<\/span> \/\/ \u9884\u671f\u503c：\u671f\u671b\u539f\u5b50\u53d8\u91cf\u7b49\u4e8ecurrent<\/span>
              \n candidate,<\/span> \/\/ \u60f3\u8981\u5199\u5165\u7684\u65b0\u503c<\/span>
              \n std::<\/span>memory_order_relaxed,<\/span> \/\/ CAS\u6210\u529f\u65f6\u7684\u5185\u5b58\u5e8f<\/span>
              \n std::<\/span>memory_order_relaxed \/\/ CAS\u5931\u8d25\u65f6\u7684\u5185\u5b58\u5e8f<\/span>
              \n )<\/span>
              \n )<\/span> {<\/span>
              \n \/*
              \n compare_exchange_weak \u5173\u952e\u884c\u4e3a：
              \n \u2705 CAS\u6210\u529f：\u8fd4\u56detrue，\u4e0d\u4f1a\u4fee\u6539current，\u539f\u5b50\u53d8\u91cf\u88ab\u5199\u6210candidate，while\u6761\u4ef6\u53d6\u53cd，\u5faa\u73af\u9000\u51fa
              \n \u274c CAS\u5931\u8d25：\u8fd4\u56defalse，**\u81ea\u52a8\u628acurrent\u8d4b\u503c\u4e3a\u539f\u5b50\u53d8\u91cf\u6b64\u523b\u771f\u5b9e\u7684\u6700\u65b0\u503c**
              \n \u5faa\u73af\u4f53\u662f\u7a7a\u7684！\u5931\u8d25\u540ecurrent\u5df2\u7ecf\u88ab\u66f4\u65b0，\u76f4\u63a5\u56de\u5230while\u5934\u90e8\u505a\u6761\u4ef6\u5224\u65ad
              \n *\/<\/span>
              \n }<\/span>
              \n}<\/span><\/p>\n

              \u5047\u8bbe\u591a\u4e2a\u7ebf\u7a0b\u540c\u65f6\u5c1d\u8bd5\u5199\u5165\u4e0d\u540c\u7684\u5019\u9009\u503c：<\/p>\n

              std::<\/span>atomic<<\/span>int<\/span>><\/span> maximum{<\/span>0<\/span>}<\/span>;<\/span><\/p>\n

              atomic_max<\/span>(<\/span>maximum,<\/span> 10<\/span>)<\/span>;<\/span>
              \natomic_max<\/span>(<\/span>maximum,<\/span> 20<\/span>)<\/span>;<\/span>
              \natomic_max<\/span>(<\/span>maximum,<\/span> 15<\/span>)<\/span>;<\/span><\/p>\n

              \u6700\u7ec8 maximum \u81f3\u5c11\u4e3a 20；\u5982\u679c\u6ca1\u6709\u5176\u4ed6\u5199\u5165\u8005\u5c06\u5176\u66f4\u65b0\u5230\u66f4\u5927\u503c，\u5219\u6700\u7ec8\u503c\u4e3a 20\u3002<\/p>\n

              \u8fd9\u91cc\u53ef\u4ee5\u4f7f\u7528 Relaxed，\u662f\u56e0\u4e3a\u7b97\u6cd5\u53ea\u4f9d\u8d56\u539f\u5b50\u6574\u6570\u672c\u8eab\u7684\u6bd4\u8f83\u4e0e\u66f4\u65b0，\u4e0d\u8d1f\u8d23\u53d1\u5e03\u5176\u4ed6\u975e\u539f\u5b50\u6570\u636e\u3002<\/p>\n

              6.4 CAS \u4e3a\u4ec0\u4e48\u901a\u5e38\u9700\u8981\u5faa\u73af？<\/h4>\n

              CAS \u7684\u66f4\u65b0\u6709\u4e00\u4e2a\u524d\u63d0：\u5b9e\u9645\u503c\u5fc5\u987b\u4e0e expected \u76f8\u7b49\u3002<\/p>\n

              \u5047\u8bbe\u7ebf\u7a0b A \u8bfb\u53d6\u5230 10，\u51c6\u5907\u66f4\u65b0\u4e3a 20；\u5728\u5b83\u6267\u884c CAS \u524d，\u7ebf\u7a0b B \u5df2\u7ecf\u628a\u503c\u6539\u4e3a 15\u3002<\/p>\n

              \u6b64\u65f6\u7ebf\u7a0b A \u7684 CAS \u4f1a\u5931\u8d25，\u5e76\u5c06 expected \u66f4\u65b0\u4e3a 15\u3002<\/p>\n

              \u5982\u679c\u4e1a\u52a1\u4ecd\u7136\u8981\u6c42\u628a\u503c\u66f4\u65b0\u5230 20，\u7ebf\u7a0b A \u5c31\u9700\u8981\u6839\u636e\u65b0\u7684\u5b9e\u9645\u503c\u91cd\u65b0\u5224\u65ad\u5e76\u5c1d\u8bd5\u66f4\u65b0\u3002<\/p>\n

              \u8fd9\u5c31\u662f CAS \u5faa\u73af\u7684\u57fa\u672c\u6a21\u5f0f\u3002<\/p>\n

              6.5 CAS \u4e0d\u80fd\u4fdd\u8bc1\u521d\u59cb\u5316\u51fd\u6570\u53ea\u6267\u884c\u4e00\u6b21<\/h4>\n

              \u4f8b\u5982：<\/p>\n

              if<\/span> (<\/span>resource.<\/span>compare_exchange_strong<\/span>(<\/span>
              \n expected,<\/span>
              \n init_resource<\/span>(<\/span>)<\/span>
              \n )<\/span>)<\/span> {<\/span>
              \n \/\/ …<\/span>
              \n}<\/span><\/p>\n

              \u8fd9\u91cc\u7684 init_resource() \u4f1a\u5728 CAS \u8c03\u7528\u524d\u6c42\u503c\u3002\u56e0\u6b64，\u591a\u4e2a\u7ebf\u7a0b\u53ef\u80fd\u90fd\u6267\u884c\u521d\u59cb\u5316\u51fd\u6570，\u53ea\u662f\u6700\u7ec8\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u6210\u529f\u53d1\u5e03\u6307\u9488\u3002<\/p>\n

              \u5982\u679c\u9700\u8981\u4fdd\u8bc1\u521d\u59cb\u5316\u903b\u8f91\u53ea\u6210\u529f\u6267\u884c\u4e00\u6b21，\u901a\u5e38\u5e94\u4f18\u5148\u8003\u8651 std::call_once：<\/p>\n

              #<\/span>include<\/span> <memory><\/span><\/span>
              \n#<\/span>include<\/span> <mutex><\/span><\/span><\/p>\n

              struct<\/span> Resource<\/span> {<\/span>
              \n int<\/span> value =<\/span> 42<\/span>;<\/span>
              \n}<\/span>;<\/span><\/p>\n

              std::<\/span>once_flag init_flag;<\/span>
              \nstd::<\/span>unique_ptr<<\/span>Resource><\/span> resource;<\/span><\/p>\n

              Resource&<\/span> get_resource<\/span>(<\/span>)<\/span> {<\/span>
              \n std::<\/span>call_once<\/span>(<\/span>init_flag,<\/span> [<\/span>]<\/span> {<\/span>
              \n resource =<\/span> std::<\/span>make_unique<\/span><<\/span>Resource><\/span><\/span><\/span>(<\/span>)<\/span>;<\/span>
              \n }<\/span>)<\/span>;<\/span><\/p>\n

              return<\/span> *<\/span>resource;<\/span>
              \n}<\/span><\/p>\n

              std::call_once \u53ef\u4ee5\u4fdd\u8bc1\u6210\u529f\u6267\u884c\u7684\u521d\u59cb\u5316\u51fd\u6570\u53ea\u6267\u884c\u4e00\u6b21，\u5e76\u5efa\u7acb\u76f8\u5e94\u7684\u540c\u6b65\u5173\u7cfb\u3002<\/p>\n

              CAS \u9002\u5408\u6784\u5efa\u9700\u8981\u81ea\u5b9a\u4e49\u72b6\u6001\u8f6c\u6362\u7684\u7b97\u6cd5，\u4f46\u4e0d\u80fd\u56e0\u4e3a\u5b83\u662f\u539f\u5b50\u64cd\u4f5c，\u5c31\u8ba4\u4e3a\u6574\u4e2a\u521d\u59cb\u5316\u3001\u8d44\u6e90\u5206\u914d\u548c\u5bf9\u8c61\u751f\u547d\u5468\u671f\u90fd\u5df2\u5b89\u5168\u3002<\/p>\n

              \u4e03\u3001C++20 \u7684\u73b0\u4ee3\u539f\u5b50\u63a5\u53e3：Wait\/Notify\u3001atomic_ref \u4e0e\u539f\u5b50\u667a\u80fd\u6307\u9488<\/h3>\n

              \u73b0\u4ee3 C++ \u7684\u539f\u5b50\u64cd\u4f5c\u4e0d\u53ea\u6709 load()\u3001store() \u548c CAS\u3002<\/p>\n

              C++20 \u8fd8\u63d0\u4f9b\u4e86\u66f4\u5b9e\u7528\u7684\u7b49\u5f85\u4e0e\u901a\u77e5\u63a5\u53e3，\u4ee5\u53ca\u9488\u5bf9\u73b0\u6709\u5bf9\u8c61\u548c\u5171\u4eab\u6240\u6709\u6743\u7684\u539f\u5b50\u64cd\u4f5c\u3002<\/p>\n

              7.1 atomic::wait \u4e0e notify：\u907f\u514d\u65e0\u610f\u4e49\u7684\u5fd9\u7b49<\/h4>\n

              \u524d\u9762\u7684\u751f\u4ea7\u8005\u2014\u6d88\u8d39\u8005\u793a\u4f8b\u4f7f\u7528\u5faa\u73af\u6301\u7eed\u68c0\u67e5\u72b6\u6001：<\/p>\n

              while<\/span> (<\/span>!<\/span>ready.<\/span>load<\/span>(<\/span>)<\/span>)<\/span> {<\/span>
              \n}<\/span><\/p>\n

              \u8fd9\u79cd\u5fd9\u7b49\u4f1a\u4e0d\u65ad\u6d88\u8017 CPU \u8d44\u6e90\u3002<\/p>\n

              C++20 \u63d0\u4f9b wait()\u3001notify_one() \u548c notify_all()，\u53ef\u4ee5\u6839\u636e\u539f\u5b50\u53d8\u91cf\u7684\u503c\u7b49\u5f85\u72b6\u6001\u53d1\u751f\u53d8\u5316\u3002<\/p>\n

              #<\/span>include<\/span> <atomic><\/span><\/span>
              \n#<\/span>include<\/span> <iostream><\/span><\/span>
              \n#<\/span>include<\/span> <thread><\/span><\/span><\/p>\n

              std::<\/span>atomic<<\/span>int<\/span>><\/span> state{<\/span>0<\/span>}<\/span>;<\/span>
              \nint<\/span> shared_data =<\/span> 0<\/span>;<\/span><\/p>\n

              void<\/span> producer<\/span>(<\/span>)<\/span> {<\/span>
              \n shared_data =<\/span> 42<\/span>;<\/span><\/p>\n

              state.<\/span>store<\/span>(<\/span>1<\/span>,<\/span> std::<\/span>memory_order_release)<\/span>;<\/span>
              \n state.<\/span>notify_one<\/span>(<\/span>)<\/span>;<\/span>
              \n}<\/span><\/p>\n

              void<\/span> consumer<\/span>(<\/span>)<\/span> {<\/span>
              \n state.<\/span>wait<\/span>(<\/span>0<\/span>,<\/span> std::<\/span>memory_order_acquire)<\/span>;<\/span><\/p>\n

              std::<\/span>cout <<<\/span> shared_data <<<\/span> '\\\\n'<\/span>;<\/span>
              \n}<\/span><\/p>\n

              int<\/span> main<\/span>(<\/span>)<\/span> {<\/span>
              \n std::<\/span>thread t1<\/span>(<\/span>producer)<\/span>;<\/span>
              \n std::<\/span>thread t2<\/span>(<\/span>consumer)<\/span>;<\/span><\/p>\n

              t1.<\/span>join<\/span>(<\/span>)<\/span>;<\/span>
              \n t2.<\/span>join<\/span>(<\/span>)<\/span>;<\/span>
              \n}<\/span><\/p>\n

              \u8fd9\u91cc：<\/p>\n

            • \u6d88\u8d39\u8005\u5728 state \u4ecd\u4e3a 0 \u65f6\u7b49\u5f85\u3002<\/li>\n
            • \u751f\u4ea7\u8005\u5199\u5165\u6570\u636e\u540e，\u5c06 state \u66f4\u65b0\u4e3a 1\u3002<\/li>\n
            • \u751f\u4ea7\u8005\u8c03\u7528 notify_one()，\u901a\u77e5\u7b49\u5f85\u7ebf\u7a0b\u3002<\/li>\n
            • \u6d88\u8d39\u8005\u89c2\u5bdf\u5230\u72b6\u6001\u53d1\u751f\u53d8\u5316\u540e\u8fd4\u56de，\u5e76\u8bfb\u53d6\u6570\u636e\u3002<\/li>\n

              \u5982\u679c\u751f\u4ea7\u8005\u5728\u6d88\u8d39\u8005\u5f00\u59cb\u7b49\u5f85\u4e4b\u524d\u5c31\u5b8c\u6210\u4e86\u72b6\u6001\u66f4\u65b0，\u6d88\u8d39\u8005\u4e5f\u4e0d\u4f1a\u56e0\u6b64\u6c38\u4e45\u9519\u8fc7\u8fd9\u6b21\u72b6\u6001\u53d8\u5316：wait(0) \u4f1a\u68c0\u67e5\u5f53\u524d\u503c，\u53d1\u73b0\u5b83\u4e0d\u518d\u7b49\u4e8e 0 \u65f6\u5373\u53ef\u8fd4\u56de\u3002<\/p>\n

              \u9700\u8981\u6ce8\u610f，\u771f\u6b63\u5efa\u7acb\u5185\u5b58\u540c\u6b65\u5173\u7cfb\u7684\u662f Release \u5199\u5165\u4e0e\u7b26\u5408\u6761\u4ef6\u7684 Acquire \u89c2\u5bdf；notify_one() \u672c\u8eab\u4e0d\u662f\u6570\u636e\u53d1\u5e03\u64cd\u4f5c\u3002<\/p>\n

              \u53e6\u5916，wait() \u4e0d\u662f\u6d88\u606f\u961f\u5217\u3002\u5b83\u4e3b\u8981\u6839\u636e\u503c\u662f\u5426\u53d8\u5316\u8fdb\u884c\u7b49\u5f85，\u5982\u679c\u72b6\u6001\u4ece 0 \u53d8\u4e3a 1 \u53c8\u53d8\u56de 0，\u7b49\u5f85\u8005\u53ef\u80fd\u65e0\u6cd5\u89c2\u5bdf\u5230\u8fd9\u6b21\u77ed\u6682\u53d8\u5316\u3002\u8fd9\u662f\u8bbe\u8ba1\u72b6\u6001\u534f\u8bae\u65f6\u9700\u8981\u8003\u8651\u7684\u95ee\u9898\u3002<\/p>\n

              7.2 atomic_ref：\u5bf9\u5df2\u6709\u5bf9\u8c61\u8fdb\u884c\u539f\u5b50\u8bbf\u95ee<\/h4>\n

              C++20 \u7684 std::atomic_ref<T> \u53ef\u4ee5\u4e3a\u7b26\u5408\u8981\u6c42\u7684\u73b0\u6709\u5bf9\u8c61\u63d0\u4f9b\u539f\u5b50\u8bbf\u95ee\u63a5\u53e3\u3002<\/p>\n

              #<\/span>include<\/span> <atomic><\/span><\/span><\/p>\n

              int<\/span> value =<\/span> 0<\/span>;<\/span><\/p>\n

              void<\/span> update<\/span>(<\/span>)<\/span> {<\/span>
              \n std::<\/span>atomic_ref<<\/span>int<\/span>><\/span> ref<\/span>(<\/span>value)<\/span>;<\/span>
              \n ref.<\/span>fetch_add<\/span>(<\/span>1<\/span>,<\/span> std::<\/span>memory_order_relaxed)<\/span>;<\/span>
              \n}<\/span><\/p>\n

              \u4f46\u8fd9\u5e76\u4e0d\u610f\u5473\u7740\u53ef\u4ee5\u968f\u610f\u6df7\u5408\u666e\u901a\u8bbf\u95ee\u4e0e\u539f\u5b50\u8bbf\u95ee\u3002<\/p>\n

              \u4f7f\u7528 atomic_ref \u65f6\u5fc5\u987b\u6ee1\u8db3\u5176\u5bf9\u9f50\u8981\u6c42\u548c\u5bf9\u8c61\u751f\u547d\u5468\u671f\u7ea6\u675f\u3002\u5728 atomic_ref \u5b9e\u4f8b\u5b58\u7eed\u671f\u95f4，\u5bf9\u88ab\u5f15\u7528\u5bf9\u8c61\u7684\u8bbf\u95ee\u5fc5\u987b\u9075\u5b88\u6807\u51c6\u89c4\u5b9a\u7684\u539f\u5b50\u8bbf\u95ee\u8981\u6c42，\u4e0d\u80fd\u518d\u8ba9\u5176\u4ed6\u7ebf\u7a0b\u901a\u8fc7\u666e\u901a\u975e\u539f\u5b50\u8bbf\u95ee\u65e0\u540c\u6b65\u5730\u8bfb\u5199\u540c\u4e00\u5bf9\u8c61\u3002<\/p>\n

              \u56e0\u6b64，atomic_ref \u66f4\u9002\u5408\u6709\u660e\u786e\u8bbf\u95ee\u534f\u8bae\u7684\u573a\u666f，\u800c\u4e0d\u662f\u7528\u6765\u7ed9\u73b0\u6709\u591a\u7ebf\u7a0b\u4ee3\u7801\u7b80\u5355\u5730\u201c\u5957\u4e00\u5c42\u539f\u5b50\u5305\u88c5\u201d\u3002<\/p>\n

              7.3 atomic<shared_ptr>：\u539f\u5b50\u53d1\u5e03\u5171\u4eab\u5bf9\u8c61<\/h4>\n

              C++20 \u63d0\u4f9b\u4e86 std::atomic<std::shared_ptr<T>> \u4e13\u95e8\u5316，\u53ef\u4ee5\u539f\u5b50\u5730\u53d1\u5e03\u6216\u66ff\u6362\u5171\u4eab\u6240\u6709\u6743\u6307\u9488\u3002<\/p>\n

              \u4f8b\u5982，\u591a\u4e2a\u7ebf\u7a0b\u9700\u8981\u8bfb\u53d6\u4e00\u4e2a\u53ea\u8bfb\u914d\u7f6e\u5bf9\u8c61，\u800c\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u5076\u5c14\u66f4\u65b0\u914d\u7f6e：<\/p>\n

              #<\/span>include<\/span> <atomic><\/span><\/span>
              \n#<\/span>include<\/span> <memory><\/span><\/span>
              \n#<\/span>include<\/span> <utility><\/span><\/span><\/p>\n

              \/\/ \u914d\u7f6e\u7ed3\u6784\u4f53，\u5b58\u653e\u4e1a\u52a1\u53c2\u6570<\/span>
              \nstruct<\/span> Config<\/span> {<\/span>
              \n int<\/span> threshold;<\/span>
              \n}<\/span>;<\/span><\/p>\n

              \/\/ \u5168\u5c40\u539f\u5b50\u5171\u4eab\u6307\u9488：\u4fdd\u5b58\u5f53\u524d\u6b63\u5728\u751f\u6548\u7684\u914d\u7f6e<\/span>
              \n\/\/ \u6307\u5411const Config：\u914d\u7f6e\u4e00\u65e6\u53d1\u5e03\u5c31\u4e0d\u53ef\u4fee\u6539，\u907f\u514d\u5e76\u53d1\u5199<\/span>
              \nstd::<\/span>atomic<<\/span>std::<\/span>shared_ptr<<\/span>const<\/span> Config>><\/span> current_config{<\/span>
              \n std::<\/span>shared_ptr<<\/span>const<\/span> Config><\/span>{<\/span>}<\/span>
              \n}<\/span>;<\/span><\/p>\n

              \/\/ \u53d1\u5e03\u65b0\u914d\u7f6e：\u751f\u4ea7\u8005\u7ebf\u7a0b\u8c03\u7528，\u5b89\u88c5\u65b0\u7248\u672c\u914d\u7f6e<\/span>
              \nvoid<\/span> publish_config<\/span>(<\/span>Config config)<\/span> {<\/span>
              \n \/\/ \u5c06\u4f20\u5165\u7684\u914d\u7f6e\u79fb\u52a8，\u6784\u9020\u5168\u65b0\u7684const Config\u5bf9\u8c61<\/span>
              \n auto<\/span> next =<\/span> std::<\/span>make_shared<\/span><<\/span>const<\/span> Config><\/span><\/span><\/span>(<\/span>
              \n std::<\/span>move<\/span>(<\/span>config)<\/span>
              \n )<\/span>;<\/span>
              \n \/\/ \u539f\u5b50\u5b58\u50a8\u65b0shared_ptr，release\u5185\u5b58\u5e8f<\/span>
              \n current_config.<\/span>store<\/span>(<\/span>
              \n std::<\/span>move<\/span>(<\/span>next)<\/span>,<\/span>
              \n std::<\/span>memory_order_release
              \n )<\/span>;<\/span>
              \n}<\/span><\/p>\n

              \/\/ \u83b7\u53d6\u5f53\u524d\u914d\u7f6e：\u6d88\u8d39\u8005\u7ebf\u7a0b\u8c03\u7528，\u62ff\u5230\u5f53\u524d\u914d\u7f6e\u5feb\u7167<\/span>
              \nstd::<\/span>shared_ptr<<\/span>const<\/span> Config><\/span> get_config<\/span>(<\/span>)<\/span> {<\/span>
              \n \/\/ \u539f\u5b50\u8bfb\u53d6shared_ptr，acquire\u5185\u5b58\u5e8f<\/span>
              \n return<\/span> current_config.<\/span>load<\/span>(<\/span>
              \n std::<\/span>memory_order_acquire
              \n )<\/span>;<\/span>
              \n}<\/span><\/p>\n

              \u8fd9\u4e2a\u8bbe\u8ba1\u6709\u51e0\u4e2a\u7279\u70b9：<\/p>\n

                \n
              • \u53d1\u5e03\u64cd\u4f5c\u539f\u5b50\u5730\u66ff\u6362\u5f53\u524d\u914d\u7f6e\u6307\u9488\u3002<\/li>\n
              • \u6d88\u8d39\u8005\u901a\u8fc7 Acquire \u83b7\u53d6\u5df2\u7ecf\u53d1\u5e03\u7684\u914d\u7f6e\u3002<\/li>\n
              • shared_ptr \u7684\u5c40\u90e8\u526f\u672c\u53ef\u4ee5\u5ef6\u957f\u5bf9\u8c61\u751f\u547d\u5468\u671f\u3002<\/li>\n
              • \u4f7f\u7528 const Config \u53ef\u4ee5\u907f\u514d\u6d88\u8d39\u8005\u901a\u8fc7\u8be5\u63a5\u53e3\u4fee\u6539\u914d\u7f6e\u3002<\/li>\n<\/ul>\n

                \u9700\u8981\u5f3a\u8c03：std::atomic<std::shared_ptr<T>> \u4e0d\u4fdd\u8bc1\u65e0\u9501\u3002\u5f15\u7528\u8ba1\u6570\u64cd\u4f5c\u4e5f\u4f1a\u4ea7\u751f\u4e00\u5b9a\u5f00\u9500\u3002<\/p>\n

                std::atomic<std::shared_ptr<const Config>>\u4e0d\u4fee\u6539\u65e7 Config \u5bf9\u8c61，\u6c38\u8fdc\u65b0\u5efa\u4e00\u4efd Config，\u66ff\u6362\u6307\u9488\u3002\u65e7\u914d\u7f6e\u5bf9\u8c61\u4f9d\u9760 shared_ptr \u5f15\u7528\u8ba1\u6570\u81ea\u52a8\u56de\u6536\u3002<\/p>\n

                \u5bf9\u4e8e\u9ad8\u9891\u56fe\u50cf\u6216\u70b9\u4e91\u7ba1\u7ebf，\u5982\u679c\u9700\u8981\u4e25\u683c\u63a7\u5236\u5ef6\u8fdf\u548c\u5185\u5b58\u5206\u914d，\u4ecd\u7136\u9700\u8981\u7ed3\u5408\u7f13\u51b2\u533a\u590d\u7528\u3001\u6240\u6709\u6743\u8f6c\u79fb\u548c\u541e\u5410\u91cf\u8981\u6c42\u8bc4\u4f30\u8bbe\u8ba1\u3002<\/p>\n

                \u516b\u3001Atomic\u3001Mutex \u4e0e Lock-Free<\/h3>\n

                8.1 \u539f\u5b50\u64cd\u4f5c\u548c\u4e92\u65a5\u9501<\/h4>\n\n\u5bf9\u6bd4\u7ef4\u5ea6std::atomicstd::mutex<\/tr>\n\n\n\n\n\n\n\n
                \u4e3b\u8981\u7528\u9014<\/td>\n\u539f\u5b50\u72b6\u6001\u66f4\u65b0\u3001\u6570\u636e\u53d1\u5e03\u3001\u6784\u5efa\u5e76\u53d1\u539f\u8bed<\/td>\n\u4fdd\u62a4\u4e34\u754c\u533a\u4e0e\u590d\u6742\u5171\u4eab\u72b6\u6001<\/td>\n<\/tr>\n
                \u4fdd\u62a4\u8303\u56f4<\/td>\n\u539f\u5b50\u5bf9\u8c61\u53ca\u5176\u64cd\u4f5c\u8bed\u4e49<\/td>\n\u53ef\u4ee5\u4fdd\u62a4\u591a\u4e2a\u53d8\u91cf\u548c\u4e00\u6bb5\u4e1a\u52a1\u903b\u8f91<\/td>\n<\/tr>\n
                \u662f\u5426\u65e0\u9501<\/td>\n\u4e0d\u4e00\u5b9a<\/td>\n\u5426<\/td>\n<\/tr>\n
                \u662f\u5426\u53ef\u80fd\u963b\u585e\u7ebf\u7a0b<\/td>\n\u539f\u5b50\u64cd\u4f5c\u672c\u8eab\u7684\u63a5\u53e3\u8bed\u4e49\u4e0d\u8981\u6c42\u8c03\u7528\u8005\u663e\u5f0f\u52a0\u9501，\u4f46\u5b9e\u73b0\u53ef\u80fd\u4f7f\u7528\u5185\u90e8\u9501<\/td>\n\u7ade\u4e89\u65f6\u53ef\u4ee5\u963b\u585e<\/td>\n<\/tr>\n
                \u7f16\u7a0b\u590d\u6742\u5ea6<\/td>\n\u7b80\u5355\u7528\u6cd5\u8f83\u4f4e，\u590d\u6742\u65e0\u9501\u7b97\u6cd5\u5f88\u9ad8<\/td>\n\u5bf9\u590d\u6742\u5171\u4eab\u72b6\u6001\u901a\u5e38\u66f4\u76f4\u89c2<\/td>\n<\/tr>\n
                \u5e38\u89c1\u95ee\u9898<\/td>\n\u5185\u5b58\u5e8f\u9519\u8bef\u3001ABA\u3001\u751f\u547d\u5468\u671f\u95ee\u9898<\/td>\n\u6b7b\u9501\u3001\u9501\u7ade\u4e89\u3001\u6301\u9501\u65f6\u95f4\u8fc7\u957f<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                \u4f8b\u5982：<\/p>\n

                std::<\/span>atomic<<\/span>int<\/span>><\/span> counter{<\/span>0<\/span>}<\/span>;<\/span><\/p>\n

                \u9002\u5408\u72ec\u7acb\u8ba1\u6570\u5668\u3002<\/p>\n

                \u4f46\u5982\u679c\u9700\u8981\u540c\u65f6\u4fee\u6539：<\/p>\n

                int<\/span> balance_a;<\/span>
                \nint<\/span> balance_b;<\/span><\/p>\n

                \u5e76\u4fdd\u8bc1\u4e24\u4e2a\u4f59\u989d\u7684\u6574\u4f53\u4e0d\u53d8\u91cf，\u90a3\u4e48\u4f7f\u7528\u4e92\u65a5\u9501\u901a\u5e38\u66f4\u6e05\u6670：<\/p>\n

                std::<\/span>mutex mtx;<\/span><\/p>\n

                void<\/span> transfer<\/span>(<\/span>int<\/span> amount)<\/span> {<\/span>
                \n std::<\/span>lock_guard<<\/span>std::<\/span>mutex><\/span> lock<\/span>(<\/span>mtx)<\/span>;<\/span><\/p>\n

                balance_a -=<\/span> amount;<\/span>
                \n balance_b +=<\/span> amount;<\/span>
                \n}<\/span><\/p>\n

                \u8fd9\u91cc\u7684\u91cd\u70b9\u662f：\u4e24\u4e2a\u53d8\u91cf\u7684\u4fee\u6539\u9700\u8981\u4f5c\u4e3a\u4e00\u4e2a\u6574\u4f53\u53d7\u5230\u4fdd\u62a4\u3002<\/p>\n

                8.2 \u4e3a\u4ec0\u4e48 Mutex \u4e0d\u4e00\u5b9a\u5f88\u6162？<\/h4>\n

                \u5728 Linux \u7b49\u5e38\u89c1\u7cfb\u7edf\u4e2d，\u4e92\u65a5\u9501\u5b9e\u73b0\u53ef\u4ee5\u901a\u8fc7\u7528\u6237\u6001\u5feb\u901f\u8def\u5f84\u5904\u7406\u65e0\u7ade\u4e89\u60c5\u51b5；\u7ade\u4e89\u4e25\u91cd\u65f6，\u624d\u53ef\u80fd\u501f\u52a9 futex \u7b49\u673a\u5236\u8fdb\u5165\u5185\u6838\u7b49\u5f85\u3002<\/p>\n

                \u56e0\u6b64，\u4e0d\u80fd\u7b80\u5355\u8ba4\u4e3a：<\/p>\n

                Atomic = \u7eb3\u79d2\u7ea7
                \nMutex = \u5fae\u79d2\u7ea7<\/p>\n

                \u8fd9\u79cd\u56fa\u5b9a\u5ef6\u8fdf\u5212\u5206\u6ca1\u6709\u666e\u904d\u610f\u4e49\u3002<\/p>\n

                \u539f\u5b50\u64cd\u4f5c\u53ef\u80fd\u56e0\u4e3a\u7f13\u5b58\u884c\u4e89\u7528\u800c\u53d8\u6162；\u4e92\u65a5\u9501\u5219\u53ef\u80fd\u5728\u65e0\u7ade\u4e89\u60c5\u51b5\u4e0b\u5f88\u9ad8\u6548\u3002<\/p>\n

                \u771f\u6b63\u9700\u8981\u6bd4\u8f83\u7684\u662f\u5177\u4f53\u7a0b\u5e8f\u5728\u76ee\u6807\u5e73\u53f0\u4e0a\u7684\u5ef6\u8fdf\u5206\u5e03\u3001\u541e\u5410\u91cf\u3001\u7ade\u4e89\u7a0b\u5ea6\u548c CPU \u6d88\u8017\u3002<\/p>\n

                8.3 Lock-Free\u3001Wait-Free \u4e0e Atomic \u7684\u533a\u522b<\/h4>\n
                  \n
                • Atomic： \u64cd\u4f5c\u6ee1\u8db3\u539f\u5b50\u8bed\u4e49\u3002<\/li>\n
                • Lock-Free： \u7b97\u6cd5\u5177\u6709\u6574\u4f53\u8fdb\u5c55\u4fdd\u8bc1，\u5728\u6301\u7eed\u6267\u884c\u7684\u5e76\u53d1\u64cd\u4f5c\u4e2d，\u4e0d\u4f1a\u56e0\u4e3a\u67d0\u4e00\u4e2a\u7ebf\u7a0b\u88ab\u963b\u585e\u800c\u4f7f\u6240\u6709\u7ebf\u7a0b\u90fd\u65e0\u6cd5\u7ee7\u7eed\u53d6\u5f97\u8fdb\u5c55\u3002<\/li>\n
                • Wait-Free： \u6bcf\u4e2a\u64cd\u4f5c\u90fd\u80fd\u5728\u6709\u9650\u4e14\u6709\u754c\u7684\u81ea\u8eab\u6267\u884c\u6b65\u9aa4\u5185\u5b8c\u6210\u3002<\/li>\n<\/ul>\n

                  Lock-Free \u4e0d\u4fdd\u8bc1\u6bcf\u4e2a\u7ebf\u7a0b\u90fd\u516c\u5e73\u5730\u5b8c\u6210\u4efb\u52a1，\u4e5f\u4e0d\u4fdd\u8bc1\u5355\u6b21\u64cd\u4f5c\u5ef6\u8fdf\u56fa\u5b9a\u3002<\/p>\n

                  Wait-Free \u7684\u8981\u6c42\u66f4\u5f3a，\u4f46\u5b9e\u73b0\u901a\u5e38\u66f4\u590d\u6742\u3002<\/p>\n

                  \u5373\u4f7f\u4f7f\u7528\u4e86\u65e0\u9501\u7684\u539f\u5b50\u6307\u4ee4，\u6574\u4e2a\u7b97\u6cd5\u4ecd\u53ef\u80fd\u56e0\u4e3a\u8bbe\u8ba1\u9519\u8bef\u800c\u9677\u5165\u6b7b\u5faa\u73af\u3001\u6d3b\u9501\u6216\u65e0\u9650\u91cd\u8bd5\u3002<\/p>\n

                  \u65e0\u9501\u662f\u7b97\u6cd5\u7684\u8fdb\u5c55\u4fdd\u8bc1，\u4e0d\u662f\u4f7f\u7528 std::atomic \u540e\u81ea\u52a8\u83b7\u5f97\u7684\u5c5e\u6027\u3002<\/p>\n

                  \u4e5d\u3001\u65e0\u9501\u7f16\u7a0b\u7684\u96be\u70b9：ABA\u3001\u5bf9\u8c61\u751f\u547d\u5468\u671f\u4e0e\u7f13\u5b58\u4e89\u7528<\/h3>\n

                  \u65e0\u9501\u7b97\u6cd5\u771f\u6b63\u56f0\u96be\u7684\u90e8\u5206\u662f\u8bc1\u660e\u6574\u4e2a\u72b6\u6001\u8f6c\u6362\u6b63\u786e\u3002<\/p>\n

                  9.1 ABA \u95ee\u9898<\/h4>\n

                  \u5047\u8bbe\u4e00\u4e2a\u539f\u5b50\u6307\u9488\u6700\u521d\u6307\u5411\u5bf9\u8c61 A：<\/p>\n

                  \u521d\u59cb\u72b6\u6001：A
                  \n \u2193
                  \n\u88ab\u4fee\u6539\u4e3a：B
                  \n \u2193
                  \n\u518d\u6b21\u53d8\u4e3a：A<\/p>\n

                  \u7ebf\u7a0b\u5728\u7b2c\u4e00\u6b21\u8bfb\u53d6\u65f6\u89c2\u5bdf\u5230 A，\u968f\u540e\u6682\u505c\u3002\u7b49\u5b83\u6062\u590d\u65f6，\u6307\u9488\u53c8\u53d8\u56de A\u3002<\/p>\n

                  CAS \u53ea\u6bd4\u8f83\u5f53\u524d\u503c\u4e0e expected，\u53ef\u80fd\u65e0\u6cd5\u5224\u65ad\u4e2d\u95f4\u5df2\u7ecf\u53d1\u751f\u8fc7\u53d8\u5316\u3002<\/p>\n

                  \u8fd9\u5c31\u662f ABA \u95ee\u9898\u3002<\/p>\n

                  ABA \u4e0d\u4e00\u5b9a\u610f\u5473\u7740\u7a0b\u5e8f\u5fc5\u7136\u9519\u8bef，\u4f46\u5982\u679c\u7b97\u6cd5\u4f9d\u8d56\u201c\u72b6\u6001\u671f\u95f4\u4ece\u672a\u53d8\u5316\u201d\u8fd9\u4e00\u5047\u8bbe，\u5c31\u53ef\u80fd\u4ea7\u751f\u903b\u8f91\u9519\u8bef\u3002<\/p>\n

                  \u5e38\u89c1\u89e3\u51b3\u601d\u8def\u5305\u62ec：<\/p>\n

                    \n
                  • \u4f7f\u7528\u5e26\u7248\u672c\u53f7\u7684\u72b6\u6001，\u6bd4\u8f83\u6307\u9488\u4e0e\u7248\u672c\u4fe1\u606f\u3002<\/li>\n
                  • \u4f7f\u7528 Hazard Pointer \u4fdd\u62a4\u6b63\u5728\u8bbf\u95ee\u7684\u5bf9\u8c61\u3002<\/li>\n
                  • \u4f7f\u7528 Epoch-Based Reclamation \u7b49\u5ef6\u8fdf\u56de\u6536\u673a\u5236\u3002<\/li>\n
                  • \u8bbe\u8ba1\u660e\u786e\u7684\u5bf9\u8c61\u6240\u6709\u6743\u4e0e\u751f\u547d\u5468\u671f\u534f\u8bae\u3002<\/li>\n<\/ul>\n

                    \u5e26\u7248\u672c\u53f7\u7684\u6307\u9488\u672c\u8eab\u4e5f\u6709\u5b9e\u73b0\u9650\u5236，\u4f8b\u5982\u539f\u5b50\u7c7b\u578b\u7684\u652f\u6301\u548c\u662f\u5426\u65e0\u9501，\u4e0d\u80fd\u5047\u5b9a\u4efb\u610f\u5bbd\u5ea6\u7684\u7ec4\u5408\u90fd\u80fd\u7531\u786c\u4ef6\u76f4\u63a5\u5b8c\u6210\u3002<\/p>\n

                    9.2 \u539f\u5b50\u6307\u9488\u4e0d\u4fdd\u8bc1\u5bf9\u8c61\u751f\u547d\u5468\u671f\u5b89\u5168<\/h4>\n

                    \u4f8b\u5982：<\/p>\n

                    std::<\/span>atomic<<\/span>Node*<\/span>><\/span> head{<\/span>nullptr<\/span>}<\/span>;<\/span><\/p>\n

                    \u5373\u4f7f head \u7684\u52a0\u8f7d\u3001\u4ea4\u6362\u548c CAS \u90fd\u662f\u539f\u5b50\u7684，\u4e5f\u4e0d\u80fd\u4fdd\u8bc1\u8bfb\u53d6\u5230\u7684 Node* \u4e00\u5b9a\u6307\u5411\u4ecd\u7136\u5b58\u6d3b\u7684\u5bf9\u8c61\u3002<\/p>\n

                    \u5982\u679c\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u5df2\u7ecf\u91ca\u653e\u5bf9\u5e94\u8282\u70b9，\u90a3\u4e48\u89e3\u5f15\u7528\u8be5\u6307\u9488\u5c31\u53ef\u80fd\u4ea7\u751f Use-After-Free\u3002<\/p>\n

                    \u56e0\u6b64：<\/p>\n

                    \u6307\u9488\u7684\u539f\u5b50\u6027\u3001\u6307\u5411\u5bf9\u8c61\u7684\u751f\u547d\u5468\u671f，\u4ee5\u53ca\u5bf9\u8c61\u5185\u5bb9\u7684\u5e76\u53d1\u8bbf\u95ee\u5b89\u5168，\u662f\u4e09\u4e2a\u72ec\u7acb\u95ee\u9898\u3002<\/p>\n

                    \u5728\u5b9e\u73b0\u65e0\u9501\u94fe\u8868\u3001\u6808\u548c\u961f\u5217\u65f6，\u5fc5\u987b\u660e\u786e\u89e3\u51b3\u5bf9\u8c61\u56de\u6536\u95ee\u9898\u3002<\/p>\n

                    9.3 atomic_flag \u4e0e\u81ea\u65cb\u9501<\/h4>\n

                    std::atomic_flag \u662f\u6700\u57fa\u7840\u7684\u539f\u5b50\u6807\u5fd7\u7c7b\u578b，\u53ef\u7528\u4e8e\u5b9e\u73b0\u81ea\u65cb\u9501\u3002<\/p>\n

                    #<\/span>include<\/span> <atomic><\/span><\/span><\/p>\n

                    class<\/span> SpinLock<\/span> {<\/span>
                    \nprivate<\/span>:<\/span>
                    \n std::<\/span>atomic_flag flag =<\/span> ATOMIC_FLAG_INIT;<\/span><\/p>\n

                    public<\/span>:<\/span>
                    \n void<\/span> lock<\/span>(<\/span>)<\/span> noexcept<\/span> {<\/span>
                    \n while<\/span> (<\/span>flag.<\/span>test_and_set<\/span>(<\/span>
                    \n std::<\/span>memory_order_acquire
                    \n )<\/span>)<\/span> {<\/span>
                    \n \/\/ \u5fd9\u7b49<\/span>
                    \n }<\/span>
                    \n }<\/span><\/p>\n

                    void<\/span> unlock<\/span>(<\/span>)<\/span> noexcept<\/span> {<\/span>
                    \n flag.<\/span>clear<\/span>(<\/span>std::<\/span>memory_order_release)<\/span>;<\/span>
                    \n }<\/span>
                    \n}<\/span>;<\/span><\/p>\n

                    \u83b7\u53d6\u9501\u65f6\u4f7f\u7528 Acquire，\u91ca\u653e\u9501\u65f6\u4f7f\u7528 Release，\u4ece\u800c\u5728\u524d\u4e00\u4e2a\u6301\u9501\u7ebf\u7a0b\u91ca\u653e\u9501\u4e0e\u540e\u4e00\u4e2a\u7ebf\u7a0b\u6210\u529f\u83b7\u53d6\u9501\u4e4b\u95f4\u5efa\u7acb\u5fc5\u8981\u7684\u540c\u6b65\u5173\u7cfb\u3002<\/p>\n

                    \u4f46\u662f，\u81ea\u65cb\u9501\u4e5f\u6709\u660e\u663e\u9650\u5236：<\/p>\n

                      \n
                    • \u7b49\u5f85\u671f\u95f4\u6301\u7eed\u6d88\u8017 CPU\u3002<\/li>\n
                    • \u9501\u7ade\u4e89\u4f1a\u5f15\u53d1\u7f13\u5b58\u4e00\u81f4\u6027\u6d41\u91cf\u3002<\/li>\n
                    • \u4e0d\u4fdd\u8bc1\u516c\u5e73\u6027\u3002<\/li>\n
                    • \u5982\u679c\u6301\u9501\u7ebf\u7a0b\u88ab\u62a2\u5360，\u5176\u4ed6\u7ebf\u7a0b\u53ef\u80fd\u957f\u65f6\u95f4\u7a7a\u8f6c\u3002<\/li>\n<\/ul>\n

                      C++20 \u7684 atomic_flag \u8fd8\u63d0\u4f9b test()\u3001wait() \u548c notify_*() \u7b49\u63a5\u53e3，\u53ef\u4ee5\u7528\u4e8e\u51cf\u5c11\u67d0\u4e9b\u573a\u666f\u4e2d\u7684\u5fd9\u7b49\u3002<\/p>\n

                      \u5728\u666e\u901a\u4e1a\u52a1\u4ee3\u7801\u4e2d，\u901a\u5e38\u4f18\u5148\u4f7f\u7528 std::mutex\u3002\u53ea\u6709\u5728\u4e34\u754c\u533a\u6781\u77ed\u3001\u7ade\u4e89\u6a21\u5f0f\u660e\u786e，\u5e76\u4e14\u7ecf\u8fc7\u6d4b\u91cf\u9a8c\u8bc1\u65f6，\u624d\u5e94\u8003\u8651\u81ea\u65cb\u9501\u3002<\/p>\n

                      9.4 False Sharing：\u6ca1\u6709\u6570\u636e\u7ade\u4e89，\u4e5f\u53ef\u80fd\u5f88\u6162<\/h4>\n

                      \u5047\u8bbe\u4e24\u4e2a\u7ebf\u7a0b\u5206\u522b\u66f4\u65b0\u4e24\u4e2a\u72ec\u7acb\u7684\u539f\u5b50\u53d8\u91cf：<\/p>\n

                      std::<\/span>atomic<<\/span>int<\/span>><\/span> counter_a{<\/span>0<\/span>}<\/span>;<\/span>
                      \nstd::<\/span>atomic<<\/span>int<\/span>><\/span> counter_b{<\/span>0<\/span>}<\/span>;<\/span><\/p>\n

                      \u5373\u4f7f\u5b83\u4eec\u4e0d\u5b58\u5728\u6570\u636e\u7ade\u4e89，\u5982\u679c\u4e24\u4e2a\u53d8\u91cf\u6070\u597d\u4f4d\u4e8e\u540c\u4e00\u7f13\u5b58\u884c，\u4e24\u4e2a\u6838\u5fc3\u7684\u5199\u5165\u4e5f\u53ef\u80fd\u5bfc\u81f4\u7f13\u5b58\u884c\u53cd\u590d\u8f6c\u79fb\u3002<\/p>\n

                      \u8fd9\u79cd\u73b0\u8c61\u79f0\u4e3a False Sharing（\u4f2a\u5171\u4eab）\u3002<\/p>\n

                      C++17 \u63d0\u4f9b\u4e86 std::hardware_destructive_interference_size，\u53ef\u4ee5\u8f85\u52a9\u8bbe\u8ba1\u7f13\u5b58\u884c\u9694\u79bb\u5e03\u5c40：<\/p>\n

                      #<\/span>include<\/span> <atomic><\/span><\/span>
                      \n#<\/span>include<\/span> <new><\/span><\/span><\/p>\n

                      struct<\/span> alignas<\/span>(<\/span>
                      \n std::<\/span>hardware_destructive_interference_size
                      \n)<\/span> Counter {<\/span>
                      \n std::<\/span>atomic<<\/span>int<\/span>><\/span> value{<\/span>0<\/span>}<\/span>;<\/span>
                      \n}<\/span>;<\/span><\/p>\n

                      Counter counter_a;<\/span>
                      \nCounter counter_b;<\/span><\/p>\n

                      \u8fd9\u79cd\u65b9\u6cd5\u53ef\u80fd\u51cf\u5c11\u4f2a\u5171\u4eab，\u4f46\u4e0d\u80fd\u4fdd\u8bc1\u6240\u6709\u5e73\u53f0\u90fd\u4ee5\u540c\u6837\u65b9\u5f0f\u5e03\u5c40，\u4e5f\u4f1a\u589e\u52a0\u5185\u5b58\u5360\u7528\u3002<\/p>\n

                      \u56e0\u6b64，\u5e94\u8be5\u5148\u4f7f\u7528\u6027\u80fd\u5206\u6790\u5de5\u5177\u786e\u8ba4\u7f13\u5b58\u884c\u4e89\u7528，\u518d\u51b3\u5b9a\u662f\u5426\u8c03\u6574\u5e03\u5c40\u3002<\/p>\n

                      \u5341\u3001\u8bbe\u8ba1\u3001\u9a8c\u8bc1\u548c\u4f18\u5316\u539f\u5b50\u64cd\u4f5c<\/h3>\n

                      10.1 \u5148\u5b9a\u4e49\u5171\u4eab\u72b6\u6001\u4e0e\u6240\u6709\u6743<\/h4>\n

                      \u5728\u7f16\u5199\u4ee3\u7801\u524d，\u5148\u56de\u7b54\u4ee5\u4e0b\u95ee\u9898：<\/p>\n

                    • \u54ea\u4e9b\u6570\u636e\u7531\u591a\u4e2a\u7ebf\u7a0b\u8bbf\u95ee？<\/li>\n
                    • \u54ea\u4e2a\u7ebf\u7a0b\u8d1f\u8d23\u5199\u5165，\u54ea\u4e9b\u7ebf\u7a0b\u8d1f\u8d23\u8bfb\u53d6？<\/li>\n
                    • \u662f\u5426\u5141\u8bb8\u591a\u4e2a\u5199\u5165\u8005？<\/li>\n
                    • \u6570\u636e\u53d1\u5e03\u4e4b\u540e\u662f\u5426\u4f1a\u88ab\u518d\u6b21\u4fee\u6539？<\/li>\n
                    • \u8c01\u8d1f\u8d23\u5bf9\u8c61\u7684\u521b\u5efa\u3001\u91ca\u653e\u548c\u590d\u7528？<\/li>\n
                    • \u662f\u5426\u9700\u8981\u4fdd\u8bc1\u591a\u4e2a\u53d8\u91cf\u4f5c\u4e3a\u4e00\u4e2a\u6574\u4f53\u66f4\u65b0？<\/li>\n

                      \u8fd9\u4e9b\u95ee\u9898\u51b3\u5b9a\u4e86\u5e94\u8be5\u4f7f\u7528\u539f\u5b50\u53d8\u91cf\u3001\u4e92\u65a5\u9501\u3001\u6d88\u606f\u961f\u5217\u8fd8\u662f\u5176\u4ed6\u540c\u6b65\u673a\u5236\u3002<\/p>\n

                      10.2 \u4f18\u5148\u9009\u62e9\u5bb9\u6613\u8bc1\u660e\u6b63\u786e\u7684\u65b9\u6848<\/h4>\n

                      \u5efa\u8bae\u6309\u4ee5\u4e0b\u987a\u5e8f\u8003\u8651：<\/p>\n

                      \u660e\u786e\u4e1a\u52a1\u4e0d\u53d8\u91cf
                      \n \u2193
                      \n\u4f18\u5148\u9009\u62e9\u7b80\u5355\u3001\u6b63\u786e\u7684\u540c\u6b65\u65b9\u5f0f
                      \n \u2193
                      \n\u9a8c\u8bc1\u541e\u5410\u91cf\u4e0e\u5ef6\u8fdf
                      \n \u2193
                      \n\u5b9a\u4f4d\u5b9e\u9645\u74f6\u9888
                      \n \u2193
                      \n\u518d\u8003\u8651\u964d\u4f4e\u5185\u5b58\u5e8f\u6216\u91c7\u7528\u65e0\u9501\u7b97\u6cd5<\/p>\n

                      \u4f8b\u5982：<\/p>\n

                        \n
                      • \u72ec\u7acb\u7edf\u8ba1\u8ba1\u6570\u5668：\u901a\u5e38\u53ef\u4ee5\u4f7f\u7528 Relaxed\u3002<\/li>\n
                      • \u7ebf\u7a0b\u9000\u51fa\u6807\u5fd7：\u5982\u679c\u53ea\u8868\u8fbe\u9000\u51fa\u72b6\u6001，Relaxed \u53ef\u80fd\u8db3\u591f；\u5982\u679c\u540c\u65f6\u53d1\u5e03\u5176\u4ed6\u6570\u636e，\u9700\u8981\u91cd\u65b0\u5206\u6790\u540c\u6b65\u5173\u7cfb\u3002<\/li>\n
                      • \u53ea\u8bfb\u914d\u7f6e\u66f4\u65b0：\u53ef\u4ee5\u8003\u8651 Release-Acquire \u4e0e\u4e0d\u53ef\u53d8\u5bf9\u8c61\u3002<\/li>\n
                      • \u591a\u53d8\u91cf\u72b6\u6001\u8f6c\u79fb：\u4f18\u5148\u8003\u8651 Mutex，\u6216\u8005\u5728\u6ee1\u8db3\u7ea6\u675f\u65f6\u539f\u5b50\u5730\u66f4\u65b0\u6574\u4f53\u72b6\u6001\u3002<\/li>\n
                      • \u9ad8\u9891\u6570\u636e\u7f13\u51b2\u533a：\u9664\u4e86\u539f\u5b50\u53d1\u5e03，\u8fd8\u8981\u89e3\u51b3\u7f13\u51b2\u533a\u6240\u6709\u6743\u3001\u590d\u7528\u4e0e\u56de\u6536\u95ee\u9898\u3002<\/li>\n<\/ul>\n

                        10.3 \u901a\u8fc7\u5de5\u5177\u9a8c\u8bc1\u5e76\u53d1\u6b63\u786e\u6027<\/h4>\n

                        \u5efa\u8bae\u5c06\u5de5\u5177\u7528\u4e8e\u4e0d\u540c\u5c42\u9762\u7684\u95ee\u9898：<\/p>\n\n\u5de5\u5177\u4e3b\u8981\u7528\u9014<\/tr>\n\n\n\n\n\n\n
                        ThreadSanitizer（TSan）<\/td>\n\u68c0\u6d4b\u8bb8\u591a\u8fd0\u884c\u8def\u5f84\u4e0a\u7684\u6570\u636e\u7ade\u4e89<\/td>\n<\/tr>\n
                        AddressSanitizer（ASan）<\/td>\n\u68c0\u6d4b\u8d8a\u754c\u3001Use-After-Free \u7b49\u5185\u5b58\u9519\u8bef<\/td>\n<\/tr>\n
                        GDB<\/td>\n\u5206\u6790\u7ebf\u7a0b\u72b6\u6001\u3001\u6b7b\u9501\u548c\u5f02\u5e38\u6267\u884c\u8def\u5f84<\/td>\n<\/tr>\n
                        perf \u7b49\u6027\u80fd\u5de5\u5177<\/td>\n\u5206\u6790 CPU \u4f7f\u7528\u3001\u7f13\u5b58\u884c\u4e3a\u548c\u6027\u80fd\u74f6\u9888<\/td>\n<\/tr>\n
                        \u57fa\u51c6\u6d4b\u8bd5<\/td>\n\u6bd4\u8f83\u4e0d\u540c\u540c\u6b65\u7b56\u7565\u7684\u541e\u5410\u91cf\u4e0e\u5ef6\u8fdf<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                        \u4f8b\u5982，\u5728\u652f\u6301\u76f8\u5e94\u5de5\u5177\u94fe\u7684\u73af\u5883\u4e2d，\u53ef\u4ee5\u4f7f\u7528：<\/p>\n

                        g++ -std<\/span>=<\/span>c++20 -O1<\/span> -g<\/span> \\\\<\/span>
                        \n -fsanitize<\/span>=<\/span>thread \\\\<\/span>
                        \n -pthread<\/span> main.cpp -o<\/span> app<\/p>\n

                        \u4f46\u9700\u8981\u6ce8\u610f：<\/p>\n

                          \n
                        • TSan \u6ca1\u6709\u62a5\u544a\u95ee\u9898，\u4e0d\u4ee3\u8868\u7a0b\u5e8f\u4e00\u5b9a\u6ca1\u6709\u5e76\u53d1\u9519\u8bef\u3002<\/li>\n
                        • TSan \u4e0d\u80fd\u8bc1\u660e\u67d0\u4e2a\u7b97\u6cd5\u5177\u6709 Lock-Free \u6216 Wait-Free \u8fdb\u5c55\u4fdd\u8bc1\u3002<\/li>\n
                        • \u6027\u80fd\u6d4b\u8bd5\u5fc5\u987b\u8003\u8651\u7ebf\u7a0b\u6570\u3001CPU \u4eb2\u548c\u6027\u3001\u7f13\u5b58\u72b6\u6001\u3001\u7ade\u4e89\u7a0b\u5ea6\u548c\u6d4b\u8bd5\u8d1f\u8f7d\u3002<\/li>\n
                        • \u4e0d\u80fd\u53ea\u6bd4\u8f83\u4e00\u6b21\u6267\u884c\u7684\u5e73\u5747\u8017\u65f6，\u8fd8\u5e94\u5173\u6ce8\u5c3e\u5ef6\u8fdf\u548c CPU \u6d88\u8017\u3002<\/li>\n<\/ul>\n

                          10.4 \u7f16\u5199\u539f\u5b50\u64cd\u4f5c\u65f6\u7684\u68c0\u67e5\u6e05\u5355<\/h4>\n

                          \u5728\u63d0\u4ea4\u5e76\u53d1\u4ee3\u7801\u524d，\u81f3\u5c11\u68c0\u67e5\u4ee5\u4e0b\u5185\u5bb9：<\/p>\n

                            \n
                          • \u6bcf\u4e2a\u5171\u4eab\u5bf9\u8c61\u7684\u5e76\u53d1\u8bfb\u5199\u662f\u5426\u7b26\u5408 C++ \u5185\u5b58\u6a21\u578b？<\/li>\n
                          • \u666e\u901a\u975e\u539f\u5b50\u6570\u636e\u662f\u5426\u901a\u8fc7\u6709\u6548\u540c\u6b65\u5173\u7cfb\u8fdb\u884c\u53d1\u5e03\u548c\u8bbf\u95ee？<\/li>\n
                          • \u9009\u7528\u7684 Memory Order \u662f\u5426\u6ee1\u8db3\u7b97\u6cd5\u9700\u8981？<\/li>\n
                          • CAS \u5931\u8d25\u65f6\u662f\u5426\u6b63\u786e\u5904\u7406 expected \u7684\u66f4\u65b0？<\/li>\n
                          • \u662f\u5426\u5b58\u5728 ABA\u3001Use-After-Free \u6216\u5176\u4ed6\u751f\u547d\u5468\u671f\u95ee\u9898？<\/li>\n
                          • \u539f\u5b50\u5bf9\u8c61\u7684\u64cd\u4f5c\u662f\u5426\u771f\u7684\u65e0\u9501？<\/li>\n
                          • \u662f\u5426\u53ef\u80fd\u51fa\u73b0\u9ad8\u7ade\u4e89\u3001\u4f2a\u5171\u4eab\u6216\u65e0\u9650\u91cd\u8bd5？<\/li>\n
                          • \u662f\u5426\u901a\u8fc7\u538b\u529b\u6d4b\u8bd5\u3001\u6570\u636e\u7ade\u4e89\u68c0\u6d4b\u548c\u6027\u80fd\u6d4b\u91cf\u9a8c\u8bc1？<\/li>\n<\/ul>\n

                            \u603b\u7ed3：C++ \u5e76\u53d1\u7f16\u7a0b<\/h3>\n
                          • \u539f\u5b50\u64cd\u4f5c\u5c42： \u64cd\u4f5c\u672c\u8eab\u662f\u5426\u4e0d\u53ef\u5206\u5272\u3002<\/li>\n
                          • \u5185\u5b58\u6a21\u578b\u5c42： \u5982\u4f55\u5efa\u7acb Sequenced-Before\u3001Synchronizes-With \u548c Happens-Before \u5173\u7cfb\u3002<\/li>\n
                          • \u540c\u6b65\u8bbe\u8ba1\u5c42： \u5982\u4f55\u6b63\u786e\u53d1\u5e03\u6570\u636e\u3001\u534f\u8c03\u7ebf\u7a0b\u5e76\u7ef4\u62a4\u5171\u4eab\u72b6\u6001\u3002<\/li>\n
                          • \u7b97\u6cd5\u5c42： \u5982\u4f55\u5904\u7406 CAS \u91cd\u8bd5\u3001ABA\u3001\u5bf9\u8c61\u751f\u547d\u5468\u671f\u4e0e\u8fdb\u5c55\u4fdd\u8bc1\u3002<\/li>\n
                          • \u5de5\u7a0b\u6027\u80fd\u5c42： \u5982\u4f55\u8bc4\u4f30\u9501\u7ade\u4e89\u3001\u7f13\u5b58\u884c\u4e89\u7528\u3001\u5185\u5b58\u5e8f\u5f00\u9500\u4e0e\u5b9e\u9645\u541e\u5410\u91cf\u3002<\/li>\n

                            \u53ef\u4ee5\u7528\u4e00\u53e5\u8bdd\u6982\u62ec：<\/p>\n

                            \u539f\u5b50\u6027\u89e3\u51b3\u5355\u6b21\u64cd\u4f5c\u7684\u4e0d\u53ef\u5206\u5272\u95ee\u9898；\u5185\u5b58\u6a21\u578b\u5b9a\u4e49\u5e76\u53d1\u8bbf\u95ee\u7684\u5408\u6cd5\u8bed\u4e49；\u540c\u6b65\u534f\u8bae\u4fdd\u8bc1\u5171\u4eab\u6570\u636e\u7684\u6b63\u786e\u4ea4\u63a5；\u65e0\u9501\u7b97\u6cd5\u5219\u9700\u8981\u8fdb\u4e00\u6b65\u8bc1\u660e\u72b6\u6001\u8f6c\u6362\u3001\u5bf9\u8c61\u751f\u547d\u5468\u671f\u548c\u8fdb\u5c55\u4fdd\u8bc1\u3002<\/p>\n

                            \u5bf9\u4e8e\u666e\u901a\u5e94\u7528\u5f00\u53d1，\u6b63\u786e\u4f7f\u7528 std::atomic \u548c std::mutex \u5df2\u7ecf\u53ef\u4ee5\u89e3\u51b3\u5927\u91cf\u95ee\u9898\u3002\u5bf9\u4e8e\u9ad8\u541e\u5410\u3001\u4f4e\u5ef6\u8fdf\u7cfb\u7edf，\u624d\u9700\u8981\u8fdb\u4e00\u6b65\u7814\u7a76 Memory Order\u3001Lock-Free\u3001ABA \u548c\u5185\u5b58\u56de\u6536\u673a\u5236\u3002<\/p>\n

                            \u6700\u7ec8\u76ee\u6807\u662f\u6784\u5efa\u4e00\u4e2a\u6b63\u786e\u3001\u53ef\u9a8c\u8bc1\u3001\u53ef\u7ef4\u62a4，\u5e76\u4e14\u7ecf\u8fc7\u5b9e\u9645\u6027\u80fd\u6d4b\u91cf\u7684\u5e76\u53d1\u7cfb\u7edf\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

                            \u4e00\u3001\u5e76\u53d1\u7f16\u7a0b\u7684\u57fa\u7840：\u539f\u5b50\u6027\u3001\u6570\u636e\u7ade\u4e89\u4e0e\u7ebf\u7a0b\u5b89\u5168
                            \n\u539f\u5b50\u64cd\u4f5c（Atomic Operation）\u662f\u73b0\u4ee3 C \u5e76\u53d1\u7f16\u7a0b\u7684\u91cd\u8981\u57fa\u7840\u3002\u5b83\u4e0d\u4ec5\u7528\u4e8e\u5b9e\u73b0\u7ebf\u7a0b\u5b89\u5168\u7684\u8ba1\u6570\u5668\u3001\u72b6\u6001\u6807\u5fd7，\u8fd8\u53ef\u4ee5\u4e0e\u5185\u5b58\u5e8f\u914d\u5408，\u6784\u5efa\u751f\u4ea7\u8005\u2014\u6d88\u8d39\u8005\u6a21\u578b\u3001\u65e0\u9501\u961f\u5217\u3001\u5171\u4eab\u72b6\u6001\u53d1\u5e03\u673a\u5236\u7b49\u5e76\u53d1\u7cfb\u7edf\u3002
                            \n\u4f46\u9700\u8981\u660e\u786e：\u539f\u5b50\u64cd\u4f5c\u4e0d\u7b49\u4e8e\u7ebf\u7a0b\u5b89\u5168，\u7ebf\u7a0b\u5b89\u5168\u4e0d\u7b49\u4e8e\u65e0\u9501，\u65e0\u9501\u4e5f\u4e0d\u7b49\u4e8e\u6027\u80fd\u66f4\u9ad8\u3002
                            \n\u8981\u7406\u89e3\u73b0\u4ee3 C \u539f\u5b50\u64cd\u4f5c&#xf<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[55,58,190,16],"topic":[],"class_list":["post-118895","post","type-post","status-publish","format-standard","hentry","category-server","tag-c","tag-linux","tag-190","tag-16"],"yoast_head":"\nC++ \u539f\u5b50\u64cd\u4f5c\u3001\u5185\u5b58\u6a21\u578b\u4e0e\u65e0\u9501\u5e76\u53d1\u7f16\u7a0b - \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\/118895.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"C++ \u539f\u5b50\u64cd\u4f5c\u3001\u5185\u5b58\u6a21\u578b\u4e0e\u65e0\u9501\u5e76\u53d1\u7f16\u7a0b - 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