{"id":4835,"date":"2020-02-28T15:23:52","date_gmt":"2020-02-28T07:23:52","guid":{"rendered":"https:\/\/www.xttblog.com\/?p=4835"},"modified":"2020-02-28T15:23:52","modified_gmt":"2020-02-28T07:23:52","slug":"java-%e9%94%81%e7%b2%97%e5%8c%96%e4%b8%8e%e5%be%aa%e7%8e%af","status":"publish","type":"post","link":"https:\/\/www.xttblog.com\/?p=4835","title":{"rendered":"Java \u9501\u7c97\u5316\u4e0e\u5faa\u73af"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">\u9501\u7c97\u5316\uff08Lock Coarsening\uff09\u3002\u9501\u7c97\u5316\u662f\u5408\u5e76\u4f7f\u7528\u76f8\u540c\u9501\u5bf9\u8c61\u7684\u76f8\u90bb\u540c\u6b65\u5757\u7684\u8fc7\u7a0b\u3002\u5982\u679c\u7f16\u8bd1\u5668\u4e0d\u80fd\u4f7f\u7528\u9501\u7701\u7565\uff08Lock Elision\uff09\u6d88\u9664\u9501\uff0c\u90a3\u4e48\u53ef\u4ee5\u4f7f\u7528\u9501\u7c97\u5316\u6765\u51cf\u5c11\u5f00\u9500\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4f17\u6240\u5468\u77e5\uff0cHotspot \u786e\u5b9e\u8fdb\u884c\u4e86\u9501\u7c97\u5316\u4f18\u5316\uff0c\u53ef\u4ee5\u6709\u6548\u5408\u5e76\u51e0\u4e2a\u76f8\u90bb\u540c\u6b65\u5757\uff0c\u4ece\u800c\u964d\u4f4e\u9501\u5f00\u9500\u3002\u80fd\u591f\u628a\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>synchronized (obj) {\n  \/\/ \u8bed\u53e5 1\n}\nsynchronized (obj) {\n  \/\/ \u8bed\u53e5 2\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8f6c\u5316\u4e3a\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>synchronized (obj) {\n  \/\/ \u8bed\u53e5 1\n  \/\/ \u8bed\u53e5 2\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\u9898\u6765\u4e86\uff0cHotspot \u80fd\u5426\u5bf9\u5faa\u73af\u8fdb\u884c\u8fd9\u79cd\u4f18\u5316\uff1f\u4f8b\u5982\uff0c\u628a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>for (...) {\n  synchronized (obj) {\n    \/\/ \u4e00\u4e9b\u64cd\u4f5c\n  }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4f18\u5316\u6210\u4e0b\u9762\u8fd9\u6837\uff1f<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>synchronized (this) {\n  for (...) {\n     \/\/ \u4e00\u4e9b\u64cd\u4f5c\n  }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u7406\u8bba\u4e0a\uff0c\u6ca1\u6709\u4ec0\u4e48\u80fd\u963b\u6b62\u6211\u4eec\u8fd9\u6837\u505a\uff0c\u751a\u81f3\u53ef\u4ee5\u628a\u8fd9\u79cd\u4f18\u5316\u770b\u4f5c\u53ea\u9488\u5bf9\u9501\u7684\u4f18\u5316\uff0c\u50cf loop unswitching \u4e00\u6837\u3002\u7136\u800c\uff0c\u7f3a\u70b9\u662f\u53ef\u80fd\u628a\u9501\u4f18\u5316\u540e\u53d8\u5f97\u8fc7\u7c97\uff0c\u7ebf\u7a0b\u5728\u6267\u884c\u5faa\u73af\u65f6\u4f1a\u5360\u636e\u6240\u6709\u7684\u9501\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Loop unswitching \u662f\u4e00\u79cd\u7f16\u8bd1\u5668\u4f18\u5316\u6280\u672f\u3002\u901a\u8fc7\u590d\u5236\u5faa\u73af\u4e3b\u4f53\uff0c\u5728 if \u548c else \u8bed\u53e5\u4e2d\u653e\u4e00\u4efd\u5faa\u73af\u4f53\u4ee3\u7801\uff0c\u5b9e\u73b0\u5c06\u6761\u4ef6\u53e5\u7684\u5185\u90e8\u5faa\u73af\u79fb\u5230\u5faa\u73af\u5916\u90e8\uff0c\u8fdb\u800c\u63d0\u9ad8\u5faa\u73af\u7684\u5e76\u884c\u6027\u3002\u7531\u4e8e\u5904\u7406\u5668\u53ef\u4ee5\u5feb\u901f\u8fd0\u7b97\u77e2\u91cf\uff0c\u56e0\u6b64\u6267\u884c\u901f\u5ea6\u5f97\u5230\u63d0\u5347\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8981\u56de\u7b54\u8fd9\u4e2a\u95ee\u9898\uff0c\u6700\u7b80\u5355\u7684\u529e\u6cd5\u5c31\u662f\u627e\u5230 Hotspot \u4f18\u5316\u7684\u8bc1\u636e\u3002\u5e78\u8fd0\u7684\u662f\uff0c\u6709\u4e86 JMH \u5e2e\u52a9\u8fd9\u9879\u5de5\u4f5c\u53d8\u5f97\u975e\u5e38\u7b80\u5355\u3002JMH \u4e0d\u4ec5\u5728\u6784\u5efa\u57fa\u51c6\u6d4b\u8bd5\u65f6\u6709\u7528\uff0c\u5e76\u4e14\u5728\u5206\u6790\u57fa\u51c6\u6d4b\u8bd5\u65b9\u9762\u540c\u6837\u597d\u7528\u3002\u8ba9\u6211\u4eec\u4ece\u4e00\u4e2a\u7b80\u5355\u7684\u57fa\u51c6\u6d4b\u8bd5\u5f00\u59cb\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>@Fork(..., jvmArgsPrepend = {\"-XX:-UseBiasedLocking\"})\n@State(Scope.Benchmark)\npublic class LockRoach {\n    int x;\n\n    @Benchmark\n    @CompilerControl(CompilerControl.Mode.DONT_INLINE)\n    public void test() {\n        for (int c = 0; c &lt; 1000; c++) {\n            synchronized (this) {\n                x += 0x42;\n            }\n        }\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5b8c\u6574\u7684\u4ee3\u7801\uff0c\u5728\u8fd9\u91cc\uff1a<a rel=\"noreferrer noopener\" aria-label=\"https:\/\/shipilev.net\/jvm\/anatomy-quarks\/1-lock-coarsening-for-loops\/LockRoach.java\uff08\u5728\u65b0\u7a97\u53e3\u6253\u5f00\uff09\" href=\"https:\/\/shipilev.net\/jvm\/anatomy-quarks\/1-lock-coarsening-for-loops\/LockRoach.java\" target=\"_blank\">https:\/\/shipilev.net\/jvm\/anatomy-quarks\/1-lock-coarsening-for-loops\/LockRoach.java<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u91cc\u6709\u4e00\u4e9b\u91cd\u8981\u7684\u6280\u5de7\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>\u4f7f\u7528 -XX:-UseBiasedLocking \u7981\u7528\u504f\u5411\u9501\uff08Biased Lock\uff09\u53ef\u4ee5\u907f\u514d\u542f\u52a8\u65f6\u95f4\u8fc7\u957f\u3002\u7531\u4e8e\u504f\u5411\u9501\u4e0d\u4f1a\u7acb\u5373\u542f\u52a8\uff0c\u5728\u521d\u59cb\u5316\u9636\u6bb5\u8981\u7b49\u5f855\u79d2\u949f\uff08\u53c2\u89c1 BiasedLockingStartupDelay \u9009\u9879\uff09<\/li><li>\u7981\u7528 @Benchmark \u65b9\u6cd5\u5185\u8054\u64cd\u4f5c\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u4ece\u53cd\u6c47\u7f16\u4e2d\u5206\u79bb\u76f8\u5173\u5185\u5bb9<\/li><li>\u52a0\u4e0a\u201c\u9b54\u6570\u201d 0x42 \u6709\u52a9\u4e8e\u5feb\u901f\u4ece\u53cd\u6c47\u7f16\u4e2d\u5b9a\u4f4d\u52a0\u6cd5\u64cd\u4f5c<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u504f\u5411\u9501\uff08Biased Locking\uff09\u3002\u5c3d\u7ba1 CAS \u539f\u5b50\u6307\u4ee4\u76f8\u5bf9\u4e8e\u91cd\u91cf\u7ea7\u9501\u6765\u8bf4\u5f00\u9500\u6bd4\u8f83\u5c0f\uff0c\u4f46\u8fd8\u662f\u5b58\u5728\u975e\u5e38\u53ef\u89c2\u7684\u672c\u5730\u5ef6\u8fdf\uff0c\u4e3a\u4e86\u5728\u65e0\u9501\u7ade\u4e89\u7684\u60c5\u51b5\u4e0b\u907f\u514d\u53d6\u9501\u83b7\u8fc7\u7a0b\u4e2d\u6267\u884c\u4e0d\u5fc5\u8981\u7684 CAS \u539f\u5b50\u6307\u4ee4\u63d0\u51fa\u4e86\u504f\u5411\u9501\u6280\u672f\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd0\u884c\u73af\u5883 i7 4790K\u3001Linux x86_64\u3001JDK EA 9b156\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Benchmark            Mode  Cnt      Score    Error  Units\nLockRoach.test       avgt    5   5331.617 \u00b1 19.051  ns\/op<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4ece\u4e0a\u9762\u8fd0\u884c\u6570\u636e\u80fd\u5206\u6790\u51fa\u4ec0\u4e48\u7ed3\u679c\uff1f\u4ec0\u4e48\u90fd\u770b\u4e0d\u51fa\u6765\uff0c\u5bf9\u5427\uff1f\u6211\u4eec\u9700\u8981\u8c03\u67e5\u80cc\u540e\u5230\u5e95\u53d1\u751f\u4e86\u4ec0\u4e48\u3002\u8fd9\u65f6 -prof perfasm \u914d\u7f6e\u53ef\u4ee5\u6d3e\u4e0a\u7528\u573a\uff0c\u5b83\u80fd\u663e\u793a\u751f\u6210\u4ee3\u7801\u4e2d\u7684\u70ed\u70b9\u533a\u57df\u3002\u7528\u9ed8\u8ba4\u8bbe\u7f6e\u8fd0\u884c\uff0c\u80fd\u591f\u53d1\u73b0\u6700\u70ed\u7684\u6307\u4ee4\u662f\u52a0\u9501 lock cmpxchg\uff08CAS\uff09\uff0c\u800c\u4e14\u53ea\u6253\u5370\u6307\u4ee4\u9644\u8fd1\u7684\u4ee3\u7801\u3002-prof perfasm:mergeMargin=1000 \u914d\u7f6e\u53ef\u4ee5\u5c06\u8fd9\u4e9b\u70ed\u70b9\u533a\u57df\u5408\u5e76\u4fdd\u5b58\u4e3a\u8f93\u51fa\u7247\u6bb5\uff0c\u4e4d\u770b\u4e4b\u4e0b\u53ef\u80fd\u89c9\u5f97\u6709\u70b9\u6050\u6016\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fdb\u4e00\u6b65\u5206\u6790\u5f97\u51fa\u8fde\u7eed\u7684\u8df3\u8f6c\u6307\u4ee4\u662f\u9501\u5b9a\u6216\u89e3\u9501\uff0c\u6ce8\u610f\u5faa\u73af\u6b21\u6570\u6700\u591a\u7684\u4ee3\u7801\uff08\u7b2c\u4e00\u5217\uff09\uff0c\u53ef\u4ee5\u770b\u5230\u6700\u70ed\u7684\u5faa\u73af\u50cf\u4e0b\u9762\u8fd9\u6837\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>&#x2197;  0x00007f455cc708c1: lea    0x20(%rsp),%rbx\n \u2502          &lt; \u7701\u7565\u82e5\u5e72\u4ee3\u7801\uff0c\u8fdb\u5165 monitor &gt;     ; &lt;--- coarsened\uff08\u7c97\u5316\uff09!\n \u2502  0x00007f455cc70918: mov    (%rsp),%r10        ; \u52a0\u8f7d $this\n \u2502  0x00007f455cc7091c: mov    0xc(%r10),%r11d    ; \u52a0\u8f7d $this.x\n \u2502  0x00007f455cc70920: mov    %r11d,%r10d        ; ...hm...\n \u2502  0x00007f455cc70923: add    $0x42,%r10d        ; ...hmmm...\n \u2502  0x00007f455cc70927: mov    (%rsp),%r8         ; ...hmmmmm!...\n \u2502  0x00007f455cc7092b: mov    %r10d,0xc(%r8)     ; LOL Hotspot\uff0c\u5197\u4f59\u5b58\u50a8\uff0c\u4e0b\u9762\u7701\u7565\u4e24\u884c\n \u2502  0x00007f455cc7092f: add    $0x108,%r11d       ; \u52a0 0x108 = 0x42 * 4 &lt;-- \u5c55\u5f004\u6b21\n \u2502  0x00007f455cc70936: mov    %r11d,0xc(%r8)     ; \u628a $this.x \u56de\u7701\u7565\u82e5\u5e72\u4ee3\u7801\uff0c\u9000\u51fa monitor &gt;      ; &lt;--- coarsened\uff08\u7c97\u5316\uff09!\n \u2502  0x00007f455cc709c6: add    $0x4,%ebp          ; c += 4   &lt;--- \u5c55\u5f004\u6b21\n \u2502  0x00007f455cc709c9: cmp    $0x3e5,%ebp        ; c &lt; 1000?\n \u2570  0x00007f455cc709cf: jl     0x00007f455cc708c1<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u54c8\u54c8\u3002\u5faa\u73af\u4f3c\u4e4e\u88ab\u5c55\u5f00\u4e864\u6b21\uff0c\u7136\u540e\u8fd94\u4e2a\u8fed\u4ee3\u4e2d\u5b9e\u73b0\u9501\u7c97\u5316\uff01\u4e3a\u4e86\u6392\u9664\u5faa\u73af\u5c55\u5f00\u5bf9\u9501\u7c97\u5316\u7684\u5f71\u54cd\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7-XX:LoopUnrollLimit=1 \u914d\u7f6e\u88c1\u526a\u5faa\u73af\u5c55\u5f00\uff0c\u518d\u6b21\u91cf\u5316\u53d7\u9650\u540e\u7684\u7c97\u5316\u6027\u80fd\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Loop unrolling\uff08\u5faa\u73af\u5c55\u5f00\uff09\uff0c\u4e5f\u79f0 Loop unwinding\uff0c\u662f\u4e00\u79cd\u5faa\u73af\u8f6c\u6362\u6280\u672f\u3002\u5b83\u8bd5\u56fe\u4ee5\u727a\u7272\u4e8c\u8fdb\u5236\u5927\u5c0f\u4e3a\u4ee3\u4ef7\u4f18\u5316\u7a0b\u5e8f\u7684\u6267\u884c\u901f\u5ea6\uff0c\u8fd9\u79cd\u65b9\u6cd5\u88ab\u79f0\u4e3a\u65f6\u7a7a\u6298\u8877\u3002\u8f6c\u6362\u53ef\u4ee5\u7531\u7a0b\u5e8f\u5458\u624b\u52a8\u6267\u884c\uff0c\u4e5f\u53ef\u4ee5\u7531\u7f16\u8bd1\u5668\u4f18\u5316\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Benchmark            Mode  Cnt      Score    Error  Units\n\n# Default\nLockRoach.test       avgt    5   5331.617 \u00b1 19.051  ns\/op\n\n# -XX:LoopUnrollLimit=1\nLockRoach.test       avgt    5  20679.043 \u00b1  3.133  ns\/op<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u54c7\uff0c\u6027\u80fd\u63d0\u5347\u4e864\u500d\uff01\u663e\u800c\u6613\u89c1\u7684\uff0c\u56e0\u4e3a\u6211\u4eec\u5df2\u7ecf\u89c2\u5bdf\u5230\u6700\u70ed\u7684\u6307\u4ee4\u662f\u52a0\u9501 lock cmpxchg\u3002\u5f53\u7136\uff0c4\u500d\u540e\u7684\u7c97\u5316\u9501\u610f\u5473\u77404\u500d\u541e\u5410\u91cf\u3002\u975e\u5e38\u9177\uff0c\u6211\u4eec\u662f\u4e0d\u662f\u53ef\u4ee5\u5ba3\u5e03\u6210\u529f\uff0c\u7136\u540e\u7ee7\u7eed\u524d\u8fdb\uff1f\u8fd8\u6ca1\u6709\u3002\u6211\u4eec\u5fc5\u987b\u9a8c\u8bc1\u7981\u7528\u5faa\u73af\u5c55\u5f00\u771f\u6b63\u63d0\u4f9b\u4e86\u6211\u4eec\u60f3\u8981\u8fdb\u884c\u6bd4\u8f83\u7684\u5185\u5bb9\u3002perfasm \u7684\u7ed3\u679c\u4f3c\u4e4e\u8868\u660e\u5b83\u542b\u6709\u7c7b\u4f3c\u7684\u70ed\u70b9\u5faa\u73af\uff0c\u53ea\u662f\u8de8\u4e86\u4e00\u5927\u6b65\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>&#x2197;  0x00007f964d0893d2: lea    0x20(%rsp),%rbx\n \u2502          &lt; \u7701\u7565\u82e5\u5e72\u4ee3\u7801\uff0c\u8fdb\u5165 monitor &gt;\n \u2502  0x00007f964d089429: mov    (%rsp),%r10        ; \u52a0\u8f7d $this\n \u2502  0x00007f964d08942d: addl   $0x42,0xc(%r10)    ; $this.x += 0x42\n \u2502          &lt; \u7701\u7565\u82e5\u5e72\u4ee3\u7801\uff0c\u9000\u51fa monitor &gt;\n \u2502  0x00007f964d0894be: inc    %ebp               ; c++\n \u2502  0x00007f964d0894c0: cmp    $0x3e8,%ebp        ; c &lt; 1000?\n \u2570  0x00007f964d0894c6: jl     0x00007f964d0893d2 ;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5f53\u9501\u7c97\u5316\u5728\u6574\u4e2a\u5faa\u73af\u4e2d\u4e0d\u8d77\u4f5c\u7528\u65f6\uff0c\u4e00\u65e6\u4e2d\u95f4\u770b\u8d77\u6765\u597d\u50cf\u5b58\u5728 N \u4e2a\u76f8\u90bb\u7684\u52a0\u9501\u89e3\u9501\u64cd\u4f5c\uff0c\u53e6\u4e00\u79cd\u5faa\u73af\u4f18\u5316\u2014\u2014\u5faa\u73af\u5c55\u5f00\u4f1a\u63d0\u4f9b\u5e38\u89c4\u9501\u7c97\u5316\u3002\u8fd9\u5c06\u63d0\u9ad8\u6027\u80fd\uff0c\u5e76\u6709\u52a9\u4e8e\u9650\u5236\u7c97\u5316\u7684\u8303\u56f4\uff0c\u4ee5\u907f\u514d\u957f\u5faa\u73af\u8fc7\u5ea6\u7c97\u5316\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u82f1\u6587\u539f\u6587\u94fe\u63a5\uff1a<a rel=\"noreferrer noopener\" aria-label=\"\uff08\u5728\u65b0\u7a97\u53e3\u6253\u5f00\uff09\" href=\"https:\/\/shipilev.net\/jvm\/anatomy-quarks\/1-lock-coarsening-for-loops\/\" target=\"_blank\">https:\/\/shipilev.net\/jvm\/anatomy-quarks\/1-lock-coarsening-for-loops\/<\/a><\/p>\n<!-- <audio autoplay=\"autoplay\" height=\"100\" width=\"100\" hidden=\"true\"><source src=\"https:\/\/c.coka.la\/orAvPR.mp3\" type=\"audio\/mp3\"\/><\/audio><img decoding=\"async\" src=\"https:\/\/images.weserv.nl\/?url=https:\/\/ws3.sinaimg.cn\/large\/8fa5dcfcgy1g4em3rzar5j20ib089ae0.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/> --><p><!-- <img decoding=\"async\" src=\"https:\/\/raw.githubusercontent.com\/xmt1139057136\/xttblog\/master\/8fa5dcfcgy1g4em3rzar5j20ib089ae0.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/>--><img decoding=\"async\" src=\"https:\/\/saas.51autoparts.cn\/api\/admin\/sys-file\/oss\/file?fileName=84db51f8561e448f9a4fda2eff0811f9.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/><\/p><p>\u6700\u540e\uff0c\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u4e2a\u4eba\u5fae\u4fe1\u516c\u4f17\u53f7\uff1a\u4e1a\u4f59\u8349\uff08yyucao\uff09\uff01<b>\u53ef\u52a0\u4f5c\u8005\u5fae\u4fe1\u53f7\uff1a<font color=\"red\">xttblog2<\/font>\u3002\u5907\u6ce8\uff1a\u201c1\u201d\uff0c\u6dfb\u52a0\u535a\u4e3b\u5fae\u4fe1\u62c9\u4f60\u8fdb\u5fae\u4fe1\u7fa4\u3002\u5907\u6ce8\u9519\u8bef\u4e0d\u4f1a\u540c\u610f\u597d\u53cb\u7533\u8bf7\u3002<\/b>\u518d\u6b21\u611f\u8c22\u60a8\u7684\u5173\u6ce8\uff01\u540e\u7eed\u6709\u7cbe\u5f69\u5185\u5bb9\u4f1a\u7b2c\u4e00\u65f6\u95f4\u53d1\u7ed9\u60a8\uff01\u539f\u521b\u6587\u7ae0\u6295\u7a3f\u8bf7\u53d1\u9001\u81f3532009913@qq.com\u90ae\u7bb1\u3002\u5546\u52a1\u5408\u4f5c\u4e5f\u53ef\u6dfb\u52a0\u4f5c\u8005\u5fae\u4fe1\u8fdb\u884c\u8054\u7cfb\uff01<\/p><p>\u672c\u6587\u539f\u6587\u51fa\u5904\uff1a<a href=\"https:\/\/www.xttblog.com\">\u4e1a\u4f59\u8349<\/a>\uff1a &raquo; <a href=\"https:\/\/www.xttblog.com\/?p=4835\">Java \u9501\u7c97\u5316\u4e0e\u5faa\u73af<\/a><\/p><!-- <div class=\"bd-reward-stl\"><button id=\"bdRewardBtn\"><span><\/span><\/button><\/div> -->","protected":false},"excerpt":{"rendered":"<p>\u9501\u7c97\u5316\uff08Lock Coarsening\uff09\u3002\u9501\u7c97\u5316\u662f\u5408\u5e76\u4f7f\u7528\u76f8\u540c\u9501\u5bf9\u8c61\u7684\u76f8\u90bb\u540c\u6b65\u5757\u7684\u8fc7\u7a0b\u3002\u5982\u679c\u7f16\u8bd1\u5668\u4e0d\u80fd\u4f7f\u7528\u9501\u7701 [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[1759,2080,622,2081,1682],"class_list":["post-4835","post","type-post","status-publish","format-standard","hentry","category-java","tag-nonreentrantlock","tag-readlock","tag-stampedlock","tag-writelock","tag-gap-locks"],"_links":{"self":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4835","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4835"}],"version-history":[{"count":1,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4835\/revisions"}],"predecessor-version":[{"id":4836,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4835\/revisions\/4836"}],"wp:attachment":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4835"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4835"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4835"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}