{"id":10008246,"date":"2023-09-07T20:58:41","date_gmt":"2023-09-07T12:58:41","guid":{"rendered":"https:\/\/blog.itmax.cn\/?p=10008246"},"modified":"2023-09-07T20:58:41","modified_gmt":"2023-09-07T12:58:41","slug":"15000%e5%ad%97%e3%80%816%e4%b8%aa%e4%bb%a3%e7%a0%81%e6%a1%88%e4%be%8b%e3%80%815%e4%b8%aa%e5%8e%9f%e7%90%86%e5%9b%be%e8%ae%a9%e4%bd%a0%e5%bd%bb%e5%ba%95%e6%90%9e%e6%87%82synchronized","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10008246","title":{"rendered":"15000\u5b57\u30016\u4e2a\u4ee3\u7801\u6848\u4f8b\u30015\u4e2a\u539f\u7406\u56fe\u8ba9\u4f60\u5f7b\u5e95\u641e\u61c2Synchronized"},"content":{"rendered":"

Synchronized<\/h2>\n

\u672c\u7bc7\u6587\u7ae0\u5c06\u56f4\u7ed5synchronized\u5173\u952e\u5b57\uff0c\u4f7f\u7528\u5927\u91cf\u56fe\u7247\u3001\u6848\u4f8b\u6df1\u5165\u6d45\u51fa\u7684\u63cf\u8ff0CAS\u3001synchronized Java\u5c42\u9762\u548cC++\u5c42\u9762\u7684\u5b9e\u73b0\u3001\u9501\u5347\u7ea7\u7684\u539f\u7406\u3001\u6e90\u7801\u7b49<\/p>\n

\u5927\u6982\u89c2\u770b\u65f6\u95f417\u5206\u949f<\/p>\n

\u53ef\u4ee5\u5e26\u7740\u51e0\u4e2a\u95ee\u9898\u53bb\u67e5\u770b\u672c\u6587\uff0c\u5982\u679c\u8ba4\u771f\u770b\u5b8c\uff0c\u95ee\u9898\u90fd\u4f1a\u8fce\u5203\u800c\u89e3\uff1a<\/p>\n

1\u3001synchronized\u662f\u600e\u4e48\u4f7f\u7528\u7684\uff1f\u5728Java\u5c42\u9762\u662f\u5982\u4f55\u5b9e\u73b0\uff1f<\/p>\n

2\u3001CAS\u662f\u4ec0\u4e48\uff1f\u80fd\u5e26\u6765\u4ec0\u4e48\u597d\u5904\uff1f\u53c8\u6709\u4ec0\u4e48\u7f3a\u70b9\uff1f<\/p>\n

3\u3001mark word\u662f\u4ec0\u4e48\uff1f\u8ddfsynchronized\u6709\u5565\u5173\u7cfb\uff1f<\/p>\n

4\u3001synchronized\u7684\u9501\u5347\u7ea7\u4f18\u5316\u662f\u4ec0\u4e48\uff1f\u5728C++\u5c42\u9762\u5982\u4f55\u5b9e\u73b0\uff1f<\/p>\n

5\u3001JDK 8 \u4e2d\u8f7b\u91cf\u7ea7\u9501CAS\u5931\u8d25\u5230\u5e95\u4f1a\u4e0d\u4f1a\u81ea\u65cb\uff1f<\/p>\n

6\u3001\u4ec0\u4e48\u662fobject monitor\uff1fwait\/notify\u65b9\u6cd5\u662f\u5982\u4f55\u5b9e\u73b0\u7684\uff1f\u4f7f\u7528synchronized\u65f6\uff0c\u7ebf\u7a0b\u963b\u585e\u540e\u662f\u5982\u4f55\u5728\u963b\u585e\u961f\u5217\u4e2d\u6392\u5e8f\u7684\uff1f<\/p>\n

…<\/p>\n

synchronized Java\u5c42\u9762\u5b9e\u73b0<\/h3>\n

synchronized\u4f5c\u7528\u5728\u4ee3\u7801\u5757\u6216\u65b9\u6cd5\u4e0a\uff0c\u7528\u4e8e\u4fdd\u8bc1\u5e76\u53d1\u73af\u5883\u4e0b\u7684\u540c\u6b65\u673a\u5236<\/strong><\/p>\n

\u4efb\u4f55\u7ebf\u7a0b\u9047\u5230synchronized\u90fd\u8981\u5148\u83b7\u53d6\u5230\u9501\u624d\u80fd\u6267\u884c\u4ee3\u7801\u5757\u6216\u65b9\u6cd5\u4e2d\u7684\u64cd\u4f5c<\/p>\n

\u5728Java\u4e2d\u6bcf\u4e2a\u5bf9\u8c61\u6709\u4e00\u4e2a\u5bf9\u5e94\u7684monitor\u5bf9\u8c61\uff08\u76d1\u89c6\u5668\uff09\uff0c\u5f53\u83b7\u53d6\u5230A\u5bf9\u8c61\u7684\u9501\u65f6\uff0cA\u5bf9\u8c61\u7684\u76d1\u89c6\u5668\u5bf9\u8c61\u4e2d\u6709\u4e2a\u5b57\u6bb5\u4f1a\u6307\u5411\u5f53\u524d\u7ebf\u7a0b\uff0c\u8868\u793a\u8fd9\u4e2a\u7ebf\u7a0b\u83b7\u53d6\u5230A\u5bf9\u8c61\u7684\u9501\uff08\u8be6\u7ec6\u539f\u7406\u540e\u6587\u63cf\u8ff0\uff09<\/p>\n

synchronized\u53ef\u4ee5\u4f5c\u7528\u4e8e\u666e\u901a\u5bf9\u8c61\u548c\u9759\u6001\u5bf9\u8c61\uff0c\u5f53\u4f5c\u7528\u4e8e\u9759\u6001\u5bf9\u8c61\u3001\u9759\u6001\u65b9\u6cd5\u65f6\uff0c\u90fd\u662f\u53bb\u83b7\u53d6\u5176\u5bf9\u5e94\u7684Class\u5bf9\u8c61\u7684\u9501<\/strong><\/p>\n

synchronized\u4f5c\u7528\u5728\u4ee3\u7801\u5757\u4e0a\u65f6\uff0c\u4f1a\u4f7f\u7528monitorentry\u548cmonitorexit\u5b57\u8282\u7801\u6307\u4ee4\u6765\u6807\u8bc6\u52a0\u9501\u3001\u89e3\u9501<\/strong><\/p>\n

synchronized\u4f5c\u7528\u5728\u65b9\u6cd5\u4e0a\u65f6\uff0c\u4f1a\u5728\u8bbf\u95ee\u6807\u8bc6\u4e0a\u52a0\u4e0asynchronized<\/strong><\/p>\n

\u6307\u4ee4\u4e2d\u53ef\u80fd\u51fa\u73b0\u4e24\u4e2amonitorexit\u6307\u4ee4\u662f\u56e0\u4e3a\u5f53\u53d1\u751f\u5f02\u5e38\u65f6\uff0c\u4f1a\u81ea\u52a8\u6267\u884cmonitorexit\u8fdb\u884c\u89e3\u9501<\/p>\n

\u6b63\u5e38\u6d41\u7a0b\u662fPC 12-14\uff0c\u5982\u679c\u5728\u6b64\u671f\u95f4\u51fa\u73b0\u5f02\u5e38\u5c31\u4f1a\u8df3\u8f6c\u5230PC 17\uff0c\u6700\u7ec8\u572819\u6267\u884cmonitorexit\u8fdb\u884c\u89e3\u9501<\/p>\n

        Object obj = new Object();\n        synchronized (obj) {\n\n        }<\/code><\/pre>\n
\"image.png\"<\/p>\n
\u5728\u4e0a\u7bc7\u6587\u7ae0<\/a>\u4e2d\u6211\u4eec\u8bf4\u8fc7\u539f\u5b50\u6027\u3001\u53ef\u89c1\u6027\u4ee5\u53ca\u6709\u5e8f\u6027<\/p>\n
synchronized\u52a0\u9501\u89e3\u9501\u7684\u5b57\u8282\u7801\u6307\u4ee4\u4f7f\u7528\u5c4f\u969c\uff0c\u52a0\u9501\u65f6\u5171\u4eab\u5185\u5b58\u4ece\u4e3b\u5185\u5b58\u4e2d\u91cd\u65b0\u8bfb\u53d6\uff0c\u89e3\u9501\u524d\u628a\u5de5\u4f5c\u5185\u5b58\u6570\u636e\u5199\u56de\u4e3b\u5185\u5b58\u4ee5\u6b64\u6765\u4fdd\u8bc1\u53ef\u89c1\u6027<\/p>\n
\u7531\u4e8e\u83b7\u53d6\u5230\u9501\u624d\u80fd\u6267\u884c\u76f8\u5f53\u4e8e\u4e32\u884c\u6267\u884c\uff0c\u4e5f\u5c31\u4fdd\u8bc1\u539f\u5b50\u6027\u548c\u6709\u5e8f\u6027\uff0c\u9700\u8981\u6ce8\u610f\u7684\u662f\u52a0\u9501\u4e0e\u89e3\u9501\u4e4b\u95f4\u7684\u6307\u4ee4\u8fd8\u662f\u53ef\u4ee5\u91cd\u6392\u5e8f\u7684<\/p>\n
CAS<\/h3>\n
\u4e3a\u4e86\u66f4\u597d\u7684\u8bf4\u660esynchronized\u539f\u7406\u548c\u9501\u5347\u7ea7\uff0c\u6211\u4eec\u5148\u6765\u804a\u804aCAS<\/p>\n
\u5728\u4e0a\u7bc7\u6587\u7ae0<\/a>\u4e2d\u6211\u4eec\u8bf4\u8fc7\uff0cvolatile\u4e0d\u80fd\u4fdd\u8bc1\u590d\u5408\u64cd\u4f5c\u7684\u539f\u5b50\u6027\uff0c\u4f7f\u7528synchronized\u65b9\u6cd5\u6216\u8005CAS\u80fd\u591f\u4fdd\u8bc1\u590d\u5408\u64cd\u4f5c\u539f\u5b50\u6027<\/p>\n
\u90a3\u4ec0\u4e48\u662fCAS\u5462\uff1f<\/p>\n
CAS\u5168\u79f0 Compare And Swap \u6bd4\u8f83\u5e76\u4ea4\u6362\uff0c\u8bfb\u53d6\u6570\u636e\u540e\u8981\u4fee\u6539\u65f6\u7528\u8bfb\u53d6\u7684\u6570\u636e\u548c\u5730\u5740\u4e0a\u7684\u503c\u8fdb\u884c\u6bd4\u8f83\uff0c\u5982\u679c\u76f8\u7b49\u90a3\u5c31\u5c06\u5730\u5740\u4e0a\u7684\u503c\u66ff\u6362\u4e3a\u76ee\u6807\u503c\uff0c\u5982\u679c\u4e0d\u76f8\u7b49\uff0c\u901a\u5e38\u4f1a\u91cd\u65b0\u8bfb\u53d6\u6570\u636e\u518d\u8fdb\u884cCAS\u64cd\u4f5c\uff0c\u4e5f\u5c31\u662f\u5931\u8d25\u91cd\u8bd5<\/strong><\/p>\n
synchronized\u52a0\u9501\u662f\u4e00\u79cd\u60b2\u89c2\u7b56\u7565\uff0c\u6bcf\u6b21\u9047\u5230\u65f6\u90fd\u8ba4\u4e3a\u4f1a\u6709\u5e76\u53d1\u95ee\u9898\uff0c\u8981\u5148\u83b7\u53d6\u9501\u624d\u64cd\u4f5c<\/p>\n
\u800cCAS\u662f\u4e00\u79cd\u4e50\u89c2\u7b56\u7565\uff0c\u6bcf\u6b21\u5148\u5927\u80c6\u7684\u53bb\u64cd\u4f5c\uff0c\u64cd\u4f5c\u5931\u8d25\uff08CAS\u5931\u8d25\uff09\u518d\u4f7f\u7528\u8865\u507f\u63aa\u65bd\uff08\u5931\u8d25\u91cd\u8bd5\uff09<\/p>\n
CAS\u4e0e\u5931\u8d25\u91cd\u8bd5\uff08\u5faa\u73af\uff09\u7684\u7ec4\u5408\u6784\u6210\u4e50\u89c2\u9501\u6216\u8005\u8bf4\u81ea\u65cb\u9501\uff08\u5faa\u73af\u5c1d\u8bd5\u5f88\u50cf\u5728\u81ea\u6211\u65cb\u8f6c\uff09<\/p>\n
\u5e76\u53d1\u5305\u4e0b\u7684\u539f\u5b50\u7c7b\uff0c\u4f9d\u9760Unsafe\u5927\u91cf\u4f7f\u7528CAS\u64cd\u4f5c\uff0c\u6bd4\u5982AtomicInteger\u7684\u81ea\u589e<\/p>\n
    public final int getAndIncrement() {\n        return unsafe.getAndAddInt(this, valueOffset, 1);\n    }\n\n    \/\/var1\u662f\u8c03\u7528\u65b9\u6cd5\u7684\u5bf9\u8c61\uff0cvar2\u662f\u9700\u8981\u8bfb\u53d6\/\u4fee\u6539\u7684\u503c\u5728\u8fd9\u4e2a\u5bf9\u8c61\u4e0a\u7684\u504f\u79fb\u91cf\uff0cvar4\u662f\u81ea\u589e1\n    public final int getAndAddInt(Object var1, long var2, int var4) {\n        int var5;\n        do {\n            \/\/var5\u662f\u901a\u8fc7\u5bf9\u8c61\u548c\u5b57\u6bb5\u504f\u79fb\u91cf\u83b7\u53d6\u5230\u5b57\u6bb5\u6700\u65b0\u503c\n            var5 = this.getIntVolatile(var1, var2);\n            \/\/cas\uff1avar1,var2\u627e\u5230\u5b57\u6bb5\u7684\u503c \u4e0e var5\u6bd4\u8f83\uff0c\u76f8\u7b49\u5c31\u66ff\u6362\u4e3a var5+var4 \n        } while(!this.compareAndSwapInt(var1, var2, var5, var5 + var4));\n        return var5;\n    }<\/code><\/pre>\n
CAS\u53ea\u80fd\u5bf9\u4e00\u4e2a\u53d8\u91cf\u8fdb\u884c\u64cd\u4f5c\uff0c\u5982\u679c\u8981\u5bf9\u591a\u4e2a\u53d8\u91cf\u8fdb\u884c\u64cd\u4f5c\uff0c\u90a3\u4e48\u53ea\u80fd\u5bf9\u5916\u5c01\u88c5\u4e00\u5c42\uff08\u5c06\u591a\u4e2a\u53d8\u91cf\u5c01\u88c5\u4e3a\u65b0\u5bf9\u8c61\u7684\u5b57\u6bb5\uff09\uff0c\u518d\u4f7f\u7528\u539f\u5b50\u7c7b\u4e2d\u7684AtomicReference<\/code><\/p>\n
\u4e0d\u77e5\u5404\u4f4d\u540c\u5b66\u6709\u6ca1\u6709\u53d1\u73b0\uff0cCAS\u7684\u6d41\u7a0b\u6709\u4e2abug\uff0c\u5c31\u662f\u5728\u8bfb\u6570\u636e\u4e0e\u6bd4\u8f83\u6570\u636e\u4e4b\u95f4\uff0c\u5982\u679c\u6570\u636e\u4eceA\u88ab\u6539\u53d8\u5230B\uff0c\u518d\u6539\u53d8\u5230A\uff0c\u90a3\u4e48CAS\u4e5f\u80fd\u6267\u884c\u6210\u529f<\/p>\n
\u8fd9\u79cd\u573a\u666f\u6709\u7684\u4e1a\u52a1\u80fd\u591f\u63a5\u53d7\uff0c\u6709\u7684\u4e1a\u52a1\u65e0\u6cd5\u63a5\u53d7\uff0c\u8fd9\u5c31\u662f\u6240\u8c13\u7684ABA\u95ee\u9898<\/p>\n
\u800c\u89e3\u51b3ABA\u95ee\u9898\u7684\u65b9\u5f0f\u6bd4\u8f83\u7b80\u5355\uff0c\u53ef\u4ee5\u518d\u6bd4\u8f83\u65f6\u9644\u52a0\u4e00\u4e2a\u81ea\u589e\u7684\u7248\u672c\u53f7\uff0cJDK\u4e5f\u63d0\u4f9b\u89e3\u51b3ABA\u95ee\u9898\u7684\u539f\u5b50\u7c7bAtomicStampedReference<\/code><\/p>\n
CAS\u80fd\u591f\u907f\u514d\u7ebf\u7a0b\u963b\u585e\uff0c\u4f46\u5982\u679c\u4e00\u76f4\u5931\u8d25\u5c31\u4f1a\u4e00\u76f4\u5faa\u73af\uff0c\u589e\u52a0CPU\u7684\u5f00\u9500\uff0cCAS\u5931\u8d25\u540e\u91cd\u8bd5\u7684\u6b21\u6570\/\u65f6\u957f\u4e0d\u597d\u8bc4\u4f30<\/strong><\/p>\n
\u56e0\u6b64CAS\u64cd\u4f5c\u9002\u7528\u4e8e\u7ade\u4e89\u5c0f\u7684\u573a\u666f\uff0c\u7528CPU\u7a7a\u8f6c\u7684\u5f00\u9500\u6765\u6362\u53d6\u7ebf\u7a0b\u963b\u585e\u6302\u8d77\/\u6062\u590d\u7684\u5f00\u9500<\/strong><\/p>\n
\u9501\u5347\u7ea7<\/h3>\n
\u65e9\u671f\u7248\u672c\u7684synchronized\u4f1a\u5c06\u83b7\u53d6\u4e0d\u5230\u9501\u7684\u7ebf\u7a0b\u76f4\u63a5\u6302\u8d77\uff0c\u6027\u80fd\u4e0d\u597d<\/p>\n
JDK 6 \u65f6\u5bf9synchronized\u7684\u5b9e\u73b0\u8fdb\u884c\u4f18\u5316\uff0c\u4e5f\u5c31\u662f\u9501\u5347\u7ea7<\/p>\n
\u9501\u7684\u72b6\u6001\u53ef\u4ee5\u5206\u4e3a\u65e0\u9501\u3001\u504f\u5411\u9501\u3001\u8f7b\u91cf\u7ea7\u9501\u3001\u91cd\u91cf\u7ea7\u9501<\/strong><\/p>\n
\u53ef\u4ee5\u6682\u65f6\u628a\u91cd\u91cf\u7ea7\u9501\u7406\u89e3\u4e3a\u65e9\u671f\u83b7\u53d6\u4e0d\u5230\u9501\u5c31\u8ba9\u7ebf\u7a0b\u6302\u8d77\uff0c\u65b0\u7684\u4f18\u5316\u4e5f\u5c31\u662f\u8f7b\u91cf\u7ea7\u9501\u548c\u504f\u5411\u9501<\/p>\n
mark word<\/h4>\n
\u4e3a\u4e86\u66f4\u597d\u7684\u8bf4\u660e\u9501\u5347\u7ea7\uff0c\u6211\u4eec\u5148\u6765\u804a\u804aJava\u5bf9\u8c61\u5934\u4e2d\u7684mark word<\/p>\n
\u6211\u4eec\u4e0b\u9762\u7684\u63a2\u7a76\u90fd\u662f\u56f4\u7ed564\u4f4d\u7684\u865a\u62df\u673a<\/p>\n
Java\u5bf9\u8c61\u7684\u5185\u5b58\u7531mark word\u3001klass word\u3001\u5982\u679c\u662f\u6570\u7ec4\u8fd8\u8981\u8bb0\u5f55\u957f\u5ea6\u3001\u5b9e\u4f8b\u6570\u636e\uff08\u5b57\u6bb5\uff09\u3001\u5bf9\u5176\u586b\u5145\uff08\u586b\u5145\u52308\u5b57\u8282\u500d\u6570\uff09\u7ec4\u6210<\/p>\n
mark word\u4f1a\u8bb0\u5f55\u9501\u72b6\u6001\uff0c\u5728\u4e0d\u540c\u9501\u72b6\u6001\u7684\u60c5\u51b5\u4e0b\u8bb0\u5f55\u7684\u6570\u636e\u4e5f\u4e0d\u540c<\/p>\n
\u4e0b\u9762\u8fd9\u4e2a\u8868\u683c\u662f\u4ece\u65e0\u9501\u5230\u91cd\u91cf\u7ea7\u9501mark word\u8bb0\u5f55\u7684\u5185\u5bb9<\/p>\n
|----------------------------------------------------------------------|--------|--------|\n| unused:25 | identity_hashcode:31 | unused:1 | age:4 | biased_lock:1  | lock:2 | \u65e0\u9501   \n|----------------------------------------------------------------------|--------|--------|\n|  thread:54 |         epoch:2      | unused:1 | age:4 | biased_lock:1 | lock:2 | \u504f\u5411\u9501\n|----------------------------------------------------------------------|--------|--------|\n|                     ptr_to_lock_record:62                            | lock:2 | \u8f7b\u91cf\u7ea7\u9501\n|----------------------------------------------------------------------|--------|--------|\n|                     ptr_to_heavyweight_monitor:62                    | lock:2 | \u91cd\u91cf\u7ea7\u9501\n|----------------------------------------------------------------------|--------|--------|<\/code><\/pre>\n
unused \u8868\u793a\u8fd8\u6ca1\u4f7f\u7528<\/p>\n
identity_hashcode \u7528\u4e8e\u8bb0\u5f55\u4e00\u81f4\u6027\u54c8\u5e0c<\/p>\n
age \u7528\u4e8e\u8bb0\u5f55GC\u5e74\u9f84<\/p>\n
biased_lock \u6807\u8bc6\u662f\u5426\u4f7f\u7528\u504f\u5411\u9501\uff0c0\u8868\u793a\u672a\u5f00\u542f\uff0c1\u8868\u793a\u5f00\u542f<\/p>\n
lock \u7528\u4e8e\u6807\u8bc6\u9501\u72b6\u6001\u6807\u5fd7\u4f4d\uff0c01\u65e0\u9501\u6216\u504f\u5411\u9501\u300100\u8f7b\u91cf\u7ea7\u9501\u300110\u91cd\u91cf\u7ea7\u9501<\/p>\n
thread \u7528\u4e8e\u6807\u8bc6\u504f\u5411\u7684\u7ebf\u7a0b<\/p>\n
epoch \u8bb0\u5f55\u504f\u5411\u7684\u65f6\u95f4\u6233<\/p>\n
ptr_to_lock_record \u8bb0\u5f55\u6808\u5e27\u4e2d\u7684\u9501\u8bb0\u5f55\uff08\u540e\u6587\u4ecb\u7ecd\uff09<\/p>\n
ptr_to_heavyweight_monitor \u8bb0\u5f55\u83b7\u53d6\u91cd\u91cf\u7ea7\u9501\u7684\u7ebf\u7a0b<\/p>\n
jol\u67e5\u770bmark word<\/h4>\n
\u6bd4\u8f83\u719f\u6089mark word\u7684\u540c\u5b66\u53ef\u4ee5\u8df3\u8fc7<\/p>\n
\u4e86\u89e3mark word\u540e\u518d\u6765\u719f\u6089\u4e0b\u4e0d\u540c\u9501\u72b6\u6001\u4e0b\u7684mark word\uff0c\u6211\u4f7f\u7528\u7684\u662fjol\u67e5\u770b\u5185\u5b58<\/p>\n
       <!-- https:\/\/mvnrepository.com\/artifact\/org.openjdk.jol\/jol-core -->\n        <dependency>\n            <groupId>org.openjdk.jol<\/groupId>\n            <artifactId>jol-core<\/artifactId>\n            <version>0.12<\/version>\n        <\/dependency><\/code><\/pre>\n
\u65e0\u9501<\/h5>\n
\u5404\u4f4d\u540c\u5b66\u5b9e\u9a8c\u65f6\u7684mark word\u53ef\u80fd\u548c\u6211\u6ce8\u91ca\u4e2d\u7684\u4e0d\u540c\uff0c\u6211\u4eec\u4e3b\u8981\u67e5\u770b\u9501\u6807\u8bc6\u7684\u503c\u548c\u662f\u5426\u542f\u7528\u504f\u5411\u9501<\/p>\n
\"image.png\"<\/p>\n
    public void noLock() {\n        Object obj = new Object();\n        \/\/mark word  00000001 \u88abunused:1\uff0cage:4\uff0cbiased_lock:1\uff0clock:2\u4f7f\u7528\uff0c001\u8868\u793a0\u672a\u542f\u7528\u504f\u5411\u9501,01\u8868\u793a\u65e0\u9501\n        \/\/01 00 00 00  (00000001 00000000 00000000 00000000)\n        \/\/00 00 00 00  (00000000 00000000 00000000 00000000)\n        ClassLayout objClassLayout = ClassLayout.parseInstance(obj);\n        System.out.println(objClassLayout.toPrintable());\n\n        \/\/\u8ba1\u7b97\u4e00\u81f4\u6027\u54c8\u5e0c\u540e\n        \/\/01 b6 ce a8\n        \/\/6a 00 00 00\n        obj.hashCode();\n        System.out.println(objClassLayout.toPrintable());\n\n        \/\/\u8fdb\u884cGC \u67e5\u770bGC\u5e74\u9f84 0 0001 0 01 \u524d2\u4f4d\u8868\u793a\u9501\u72b6\u600101\u65e0\u9501\uff0c\u7b2c\u4e09\u4f4dbiased_lock\u4e3a0\u8868\u793a\u672a\u542f\u7528\u504f\u5411\u9501\uff0c\u540e\u7eed\u56db\u4f4d\u5219\u662fGC\u5e74\u9f84age 1\n        \/\/09 b6 ce a8 (00001001 10110110 11001110 10101000)\n        \/\/6a 00 00 00 (01101010 00000000 00000000 00000000)\n        System.gc();\n        System.out.println(objClassLayout.toPrintable());\n    }<\/code><\/pre>\n
\u8f7b\u91cf\u7ea7\u9501<\/h5>\n
    public void lightLockTest() throws InterruptedException {\n        Object obj = new Object();\n        ClassLayout objClassLayout = ClassLayout.parseInstance(obj);\n        \/\/1334729950\n        System.out.println(obj.hashCode());\n        \/\/0 01 \u65e0\u9501\n        \/\/01 4e c0 d5 (00000001 01001110 11000000 11010101)\n        \/\/6a 00 00 00 (01101010 00000000 00000000 00000000)\n        System.out.println(Thread.currentThread().getName() + ":");\n        System.out.println(objClassLayout.toPrintable());\n\n\n        Thread thread1 = new Thread(() -> {\n            synchronized (obj) {\n                \/\/ 110110 00 \u4e2d\u768400\u8868\u793a\u8f7b\u91cf\u7ea7\u9501\u5176\u4ed662\u4f4d\u6307\u5411\u62e5\u6709\u9501\u7684\u7ebf\u7a0b\n                \/\/d8 f1 5f 1d (11011000 11110001 01011111 00011101)\n                \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n                System.out.println(Thread.currentThread().getName() + ":");\n                System.out.println(objClassLayout.toPrintable());\n\n                \/\/1334729950\n                \/\/\u65e0\u9501\u5347\u7ea7\u6210\u8f7b\u91cf\u7ea7\u9501\u540e hashcode\u672a\u53d8 \u5bf9\u8c61\u5934\u4e2d\u6ca1\u5b58\u50a8hashcode \u53ea\u5b58\u50a8\u62e5\u6709\u9501\u7684\u7ebf\u7a0b\n                \/\/\uff08\u5b9e\u9645\u4e0amark word\u5185\u5bb9\u88ab\u5b58\u50a8\u5230lock record\u4e2d\uff0c\u6240\u4ee5hashcode\u4e5f\u88ab\u5b58\u50a8\u5230lock record\u4e2d\uff09\n                System.out.println(obj.hashCode());\n            }\n        }, "t1");\n\n        thread1.start();\n        \/\/\u7b49\u5f85t1\u6267\u884c\u5b8c \u907f\u514d \u53d1\u751f\u7ade\u4e89\n        thread1.join();\n\n        \/\/\u8f7b\u91cf\u7ea7\u9501 \u91ca\u653e\u540e mark word \u6062\u590d\u6210\u65e0\u9501 \u5b58\u50a8\u54c8\u5e0ccode\u7684\u72b6\u6001\n        \/\/01 4e c0 d5 (00000001 01001110 11000000 11010101)\n        \/\/6a 00 00 00 (01101010 00000000 00000000 00000000)\n        System.out.println(Thread.currentThread().getName() + ":");\n        System.out.println(objClassLayout.toPrintable());\n\n        Thread thread2 = new Thread(() -> {\n            synchronized (obj) {\n                \/\/001010 00 \u4e2d\u768400\u8868\u793a\u8f7b\u91cf\u7ea7\u9501\u5176\u4ed662\u4f4d\u6307\u5411\u62e5\u6709\u9501\u7684\u7ebf\u7a0b\n                \/\/28 f6 5f 1d (00101000 11110110 01011111 00011101)\n                \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n                System.out.println(Thread.currentThread().getName() + ":");\n                System.out.println(objClassLayout.toPrintable());\n            }\n        }, "t2");\n        thread2.start();\n        thread2.join();\n    }<\/code><\/pre>\n
\u504f\u5411\u9501<\/h5>\n
    public void biasedLockTest() throws InterruptedException {\n        \/\/\u5ef6\u8fdf\u8ba9\u504f\u5411\u9501\u542f\u52a8\n        Thread.sleep(5000);\n\n        Object obj = new Object();\n        ClassLayout objClassLayout = ClassLayout.parseInstance(obj);\n\n        \/\/1 01 \u533f\u540d\u504f\u5411\u9501 \u8fd8\u672a\u8bbe\u7f6e\u504f\u5411\u7ebf\u7a0b\n        \/\/05 00 00 00 (00000101 00000000 00000000 00000000)\n        \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n        System.out.println(Thread.currentThread().getName() + ":");\n        System.out.println(objClassLayout.toPrintable());\n\n        synchronized (obj) {\n            \/\/\u504f\u5411\u9501 \u8bb0\u5f55 \u7ebf\u7a0b\u5730\u5740\n            \/\/05 30 e3 02 (00000101 00110000 11100011 00000010)\n            \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n            System.out.println(Thread.currentThread().getName() + ":");\n            System.out.println(objClassLayout.toPrintable());\n        }\n\n        Thread thread1 = new Thread(() -> {\n            synchronized (obj) {\n                \/\/\u81a8\u80c0\u4e3a\u8f7b\u91cf\u7ea7 0 00 0\u672a\u542f\u7528\u504f\u5411\u9501,00\u8f7b\u91cf\u7ea7\u9501\n                \/\/68 f4 a8 1d (01101000 11110100 10101000 00011101)\n                \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n                System.out.println(Thread.currentThread().getName() + ":");\n                System.out.println(objClassLayout.toPrintable());\n            }\n        }, "t1");\n\n        thread1.start();\n        thread1.join();\n    }<\/code><\/pre>\n
\u91cd\u91cf\u7ea7\u9501<\/h5>\n
    public void heavyLockTest() throws InterruptedException {\n        Object obj = new Object();\n        ClassLayout objClassLayout = ClassLayout.parseInstance(obj);\n        Thread thread1 = new Thread(() -> {\n            synchronized (obj) {\n                \/\/\u7b2c\u4e00\u6b21 00 \u8868\u793a \u8f7b\u91cf\u7ea7\u9501\n                \/\/d8 f1 c3 1e (11011000 11110001 11000011 00011110)\n                \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n                System.out.println(Thread.currentThread().getName() + ":");\n                System.out.println(objClassLayout.toPrintable());\n\n                \/\/\u7528debug\u63a7\u5236t2\u6765\u7ade\u4e89\n                \/\/\u7b2c\u4e8c\u6b21\u6253\u5370 \u53d8\u6210 10 \u8868\u793a\u81a8\u80c0\u4e3a\u91cd\u91cf\u7ea7\u9501\uff08t2\u7ade\u4e89\uff09  \u5176\u4ed662\u4f4d\u6307\u5411\u76d1\u89c6\u5668\u5bf9\u8c61\n                \/\/fa 21 3e 1a (11111010 00100001 00111110 00011010)\n                \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n                System.out.println(Thread.currentThread().getName() + ":");\n                System.out.println(objClassLayout.toPrintable());\n            }\n        }, "t1");\n\n        thread1.start();\n\n        Thread thread2 = new Thread(() -> {\n            synchronized (obj) {\n                \/\/t2\u7ade\u4e89 \u81a8\u80c0\u4e3a \u91cd\u91cf\u7ea7\u9501 111110 10 10\u4e3a\u91cd\u91cf\u7ea7\u9501\n                \/\/fa 21 3e 1a (11111010 00100001 00111110 00011010)\n                \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n                System.out.println(Thread.currentThread().getName() + ":");\n                System.out.println(objClassLayout.toPrintable());\n            }\n        }, "t2");\n        thread2.start();\n\n        thread1.join();\n        thread2.join();\n\n        \/\/10 \u91cd\u91cf\u7ea7\u9501 \u672a\u53d1\u751f\u9501\u964d\u7ea7\n        \/\/3a 36 4d 1a (00111010 00110110 01001101 00011010)\n        \/\/00 00 00 00 (00000000 00000000 00000000 00000000)\n        System.out.println(Thread.currentThread().getName() + ":");\n        System.out.println(objClassLayout.toPrintable());\n    }<\/code><\/pre>\n
\u8f7b\u91cf\u7ea7\u9501<\/h4>\n
\u8f7b\u91cf\u7ea7\u9501\u7684\u63d0\u51fa\u662f\u4e3a\u4e86\u51cf\u5c0f\u4f20\u7edf\u91cd\u91cf\u7ea7\u9501\u4f7f\u7528\u4e92\u65a5\u91cf\uff08\u6302\u8d77\/\u6062\u590d\u7ebf\u7a0b\uff09\u6240\u4ea7\u751f\u7684\u5f00\u9500<\/strong><\/p>\n
\u9762\u5bf9\u8f83\u5c11\u7684\u7ade\u4e89\u573a\u666f\u65f6\uff0c\u83b7\u53d6\u9501\u7684\u65f6\u95f4\u603b\u662f\u77ed\u6682\u7684\uff0c\u800c\u6302\u8d77\u7ebf\u7a0b\u7528\u6237\u6001\u3001\u5185\u6838\u6001\u7684\u5f00\u9500\u6bd4\u8f83\u5927\uff0c\u4f7f\u7528\u8f7b\u91cf\u7ea7\u9501\u51cf\u5c11\u5f00\u9500<\/p>\n
\u90a3\u4e48\u8f7b\u91cf\u7ea7\u9501\u662f\u5982\u4f55\u5b9e\u73b0\u7684\u5462\uff1f<\/p>\n
\u8f7b\u91cf\u7ea7\u9501\u4e3b\u8981\u7531lock record\u3001mark word\u3001CAS\u6765\u5b9e\u73b0,lock record\u5b58\u50a8\u5728\u7ebf\u7a0b\u7684\u6808\u5e27\u4e2d\uff0c\u6765\u8bb0\u5f55\u9501\u7684\u4fe1\u606f<\/p>\n
\u52a0\u9501<\/h5>\n
\u67e5\u770b\u5bf9\u8c61\u662f\u4e0d\u662f\u65e0\u9501\u72b6\u6001\uff0c\u5982\u679c\u5bf9\u8c61\u662f\u65e0\u9501\u72b6\u6001\uff0c\u4f1a\u5c06mark word\u590d\u5236\u5230lock record\u9501\u8bb0\u5f55\u4e2d\u7684displaced mark word<\/strong><\/p>\n
\"image.png\"<\/p>\n
\u7136\u540e\u518d\u5c1d\u8bd5\u4f7f\u7528CAS\u5c1d\u8bd5\u5c06mark word\u4e2d\u90e8\u5206\u5185\u5bb9\u66ff\u6362\u6307\u5411\u8fd9\u4e2alock record<\/strong>\uff0c\u5982\u679c\u6210\u529f\u8868\u793a\u83b7\u53d6\u9501\u6210\u529f<\/p>\n
\"image.png\"<\/p>\n
\u5982\u679c\u5bf9\u8c61\u6301\u6709\u9501\uff0c\u4f1a\u67e5\u770b\u6301\u6709\u9501\u7684\u7ebf\u7a0b\u662f\u4e0d\u662f\u5f53\u524d\u7ebf\u7a0b\uff0c\u8fd9\u79cd\u53ef\u91cd\u5165\u7684\u60c5\u51b5\u4e0block record\u4e2d\u8bb0\u5f55\u4e0d\u518d\u662fmark word\u800c\u662fnull<\/strong><\/p>\n
\u53ef\u91cd\u5165\u7684\u60c5\u51b5\u4e0b\uff0c\u53ea\u9700\u8981\u8fdb\u884c\u81ea\u589e\u8ba1\u6570\u5373\u53ef\uff0c\u89e3\u9501\u65f6\u9047\u5230null\u7684lock record\u5219\u6263\u51cf<\/p>\n
\"image.png\"<\/p>\n
\u5982\u679cCAS\u5931\u8d25\u6216\u8005\u6301\u6709\u9501\u7684\u7ebf\u7a0b\u4e0d\u662f\u5f53\u524d\u7ebf\u7a0b\uff0c\u5c31\u4f1a\u89e6\u53d1\u9501\u81a8\u80c0<\/strong><\/p>\n
\u5173\u952e\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
void ObjectSynchronizer::slow_enter(Handle obj, BasicLock* lock, TRAPS) {\n  \/\/\u5f53\u524d\u5bf9\u8c61\u7684mark word\n  markOop mark = obj->mark();\n  assert(!mark->has_bias_pattern(), "should not see bias pattern here");\n\n  \/\/\u5982\u679c\u5f53\u524d\u5bf9\u8c61\u662f\u65e0\u9501\u72b6\u6001 \n  if (mark->is_neutral()) {\n    \/\/\u5c06mark word\u590d\u5236\u5230lock record\n    lock->set_displaced_header(mark);\n    \/\/CAS\u5c06\u5f53\u524d\u5bf9\u8c61\u7684mark word\u5185\u5bb9\u66ff\u6362\u4e3a\u6307\u5411lock record\n    if (mark == (markOop) Atomic::cmpxchg_ptr(lock, obj()->mark_addr(), mark)) {\n      TEVENT (slow_enter: release stacklock) ;\n      return ;\n    }\n  } else\n  \/\/\u5982\u679c\u6709\u9501  \u5224\u65ad\u662f\u4e0d\u662f\u5f53\u524d\u7ebf\u7a0b\u83b7\u53d6\u9501\n  if (mark->has_locker() && THREAD->is_lock_owned((address)mark->locker())) {\n    assert(lock != mark->locker(), "must not re-lock the same lock");\n    assert(lock != (BasicLock*)obj->mark(), "don't relock with same BasicLock");\n    \/\/\u53ef\u91cd\u5165\u9501 \u590d\u5236null\n    lock->set_displaced_header(NULL);\n    return;\n  }\n\n  \/\/\u6709\u9501\u5e76\u4e14\u83b7\u53d6\u9501\u7684\u7ebf\u7a0b\u4e0d\u662f\u5f53\u524d\u7ebf\u7a0b \u6216\u8005 CAS\u5931\u8d25 \u8fdb\u884c\u81a8\u80c0\n  lock->set_displaced_header(markOopDesc::unused_mark());\n  ObjectSynchronizer::inflate(THREAD, obj())->enter(THREAD);\n}<\/code><\/pre>\n
\u89e3\u9501<\/h5>\n
\u67e5\u770block record\u4e2d\u590d\u5236\u7684\u5185\u5bb9\u662f\u4e0d\u662f\u7a7a\uff0c\u662f\u7a7a\u8bf4\u660e\u662f\u53ef\u91cd\u5165\u9501<\/strong><\/p>\n
\u4e0d\u4e3a\u7a7a\u5219\u67e5\u770bmark word\u662f\u5426\u6307\u5411lock record\uff0c\u5982\u679c\u6307\u5411\u5219CAS\u5c1d\u8bd5\u5c06mark word\u8bb0\u5f55\u6307\u5411lock record\u66ff\u6362\u4e3alock record\u4e2d\u7684displaced mark word<\/strong>\uff08\u4e5f\u5c31\u662f\u539f\u6765\u7684mark word\uff09<\/p>\n
\u5982\u679cmark word\u4e0d\u6307\u5411lock record \u6216\u8005 CAS\u5931\u8d25\u4e86 \u8bf4\u660e\u5b58\u5728\u7ade\u4e89\uff0c\u5176\u4ed6\u7ebf\u7a0b\u52a0\u9501\u5931\u8d25\u8ba9mark word\u6307\u5411\u91cd\u91cf\u7ea7\u9501\uff0c\u76f4\u63a5\u81a8\u80c0<\/p>\n
\"image.png\"<\/p>\n
\u5173\u952e\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
void ObjectSynchronizer::fast_exit(oop object, BasicLock* lock, TRAPS) {\n  assert(!object->mark()->has_bias_pattern(), "should not see bias pattern here");\n\n  \/\/\u83b7\u53d6\u590d\u5236\u7684mark word\n  markOop dhw = lock->displaced_header();\n  markOop mark ;\n  \/\/\u5982\u679c\u4e3a\u7a7a \u8bf4\u660e\u662f\u53ef\u91cd\u5165\n  if (dhw == NULL) {\n     \/\/ Recursive stack-lock.\n     \/\/ Diagnostics -- Could be: stack-locked, inflating, inflated.\n     mark = object->mark() ;\n     assert (!mark->is_neutral(), "invariant") ;\n     if (mark->has_locker() && mark != markOopDesc::INFLATING()) {\n        assert(THREAD->is_lock_owned((address)mark->locker()), "invariant") ;\n     }\n     if (mark->has_monitor()) {\n        ObjectMonitor * m = mark->monitor() ;\n        assert(((oop)(m->object()))->mark() == mark, "invariant") ;\n        assert(m->is_entered(THREAD), "invariant") ;\n     }\n     return ;\n  }\n\n  mark = object->mark() ;\n\n  \/\/\u5982\u679cmark word\u6307\u5411lock record\n  if (mark == (markOop) lock) {\n     assert (dhw->is_neutral(), "invariant") ;\n     \/\/\u5c1d\u8bd5CAS\u5c06\u6307\u5411lock record\u7684mark word\u66ff\u6362\u4e3a\u539f\u6765\u7684\u5185\u5bb9\n     if ((markOop) Atomic::cmpxchg_ptr (dhw, object->mark_addr(), mark) == mark) {\n        TEVENT (fast_exit: release stacklock) ;\n        return;\n     }\n  }\n\n  \/\/\u672a\u6307\u5411\u5f53\u524dlock record\u6216\u8005CAS\u5931\u8d25\u5219\u81a8\u80c0\n  ObjectSynchronizer::inflate(THREAD, object)->exit (true, THREAD) ;\n}<\/code><\/pre>\n
\u504f\u5411\u9501<\/h4>\n
hotspot\u5f00\u53d1\u4eba\u5458\u6d4b\u8bd5\uff0c\u5728\u67d0\u4e9b\u573a\u666f\u4e0b\uff0c\u603b\u662f\u540c\u4e00\u4e2a\u7ebf\u7a0b\u83b7\u53d6\u9501\uff0c\u5728\u8fd9\u79cd\u573a\u666f\u4e0b\uff0c\u5e0c\u671b\u7528\u66f4\u5c0f\u7684\u5f00\u9500\u6765\u83b7\u53d6\u9501<\/p>\n
\u5f53\u5f00\u542f\u504f\u5411\u9501\u540e\uff0c\u5982\u679c\u662f\u65e0\u9501\u72b6\u6001\u4f1a\u5c06mark word\u6539\u4e3a\u504f\u5411\u67d0\u4e2a\u7ebf\u7a0bID\uff0c\u4ee5\u6b64\u6807\u8bc6\u8fd9\u4e2a\u7ebf\u7a0b\u83b7\u53d6\u9501\uff08\u9501\u504f\u5411\u8fd9\u4e2a\u7ebf\u7a0b\uff09<\/p>\n
\u5982\u679c\u6b63\u5904\u4e8e\u504f\u5411\u9501\uff0c\u9047\u5230\u7ade\u4e89\u53ef\u80fd\u81a8\u80c0\u4e3a\u8f7b\u91cf\u7ea7\u9501\uff0c\u5982\u679c\u8981\u5b58\u50a8\u4e00\u81f4\u6027\u54c8\u5e0c\u7b49\u60c5\u51b5\u4e5f\u4f1a\u81a8\u80c0\u4e3a\u91cd\u91cf\u7ea7\u9501<\/p>\n
JDK8\u9ed8\u8ba4\u5f00\u542f\u504f\u5411\u9501\uff0c\u5728\u9ad8\u7248\u672cJDK\u9ed8\u8ba4\u4e0d\u5f00\u542f\u504f\u5411\u9501\uff0c\u53ef\u80fd\u56e0\u4e3a\u504f\u5411\u9501\u7684\u7ef4\u62a4\u8d85\u8fc7\u6536\u76ca\uff0c\u6211\u4eec\u4e5f\u4e0d\u6df1\u5165\u8fdb\u884c\u7814\u7a76<\/p>\n
\u91cd\u91cf\u7ea7\u9501<\/h4>\n
object monitor<\/h5>\n
\u4f7f\u7528object monitor\u5bf9\u8c61\u6765\u5b9e\u73b0\u91cd\u91cf\u7ea7\u9501<\/p>\n
object monitor\u4e2d\u4f7f\u7528\u4e00\u4e9b\u5b57\u6bb5\u8bb0\u5f55\u4fe1\u606f\uff0c\u6bd4\u5982\uff1aobject\u5b57\u6bb5\u7528\u4e8e\u8bb0\u5f55\u9501\u7684\u90a3\u4e2a\u5bf9\u8c61\uff0cheader\u5b57\u6bb5\u7528\u4e8e\u8bb0\u5f55\u9501\u7684\u90a3\u4e2a\u5bf9\u8c61\u7684mark word\u3001owner\u5b57\u6bb5\u7528\u4e8e\u8bb0\u5f55\u6301\u6709\u9501\u7684\u7ebf\u7a0b<\/p>\n
object monitor\u4f7f\u7528\u963b\u585e\u961f\u5217\u6765\u5b58\u50a8\u7ade\u4e89\u4e0d\u5230\u9501\u7684\u7ebf\u7a0b\uff0c\u4f7f\u7528\u7b49\u5f85\u961f\u5217\u6765\u5b58\u50a8\u8c03\u7528wait\u8fdb\u5165\u7b49\u5f85\u72b6\u6001\u7684\u7ebf\u7a0b<\/strong><\/p>\n
\u963b\u585e\u961f\u5217\u548c\u7b49\u5f85\u961f\u5217\u7c7b\u6bd4\u7740\u5e76\u53d1\u5305\u4e0b\u7684AQS\u548cCondition<\/p>\n
object monitor\u4f7f\u7528cxq\u6808\u548centry list\u961f\u5217\u6765\u5b9e\u73b0\u963b\u585e\u961f\u5217\uff0c\u5176\u4e2dcxq\u6808\u4e2d\u5b58\u50a8\u6709\u7ade\u4e89\u7684\u7ebf\u7a0b\uff0centry list\u5b58\u50a8\u5df2\u7ecf\u7ade\u4e89\u5931\u8d25\u8f83\u7a33\u5b9a\u7684\u7ebf\u7a0b\uff1b\u4f7f\u7528wait set\u5b9e\u73b0\u7b49\u5f85\u961f\u5217<\/strong><\/p>\n
\u5f53\u7ebf\u7a0b\u8c03\u7528wait\u65f6\uff0c\u8fdb\u5165wait set\u7b49\u5f85\u961f\u5217<\/strong><\/p>\n
\u800c\u8c03\u7528notify\u65f6\uff0c\u53ea\u662f\u5c06\u7b49\u5f85\u961f\u5217\u7684\u961f\u5934\u8282\u70b9\u52a0\u5165cxq\uff0c\u5e76\u6ca1\u6709\u5524\u9192\u8be5\u7ebf\u7a0b\u53bb\u7ade\u4e89<\/strong><\/p>\n
\u771f\u6b63\u7684\u5524\u9192\u7ebf\u7a0b\u662f\u5728\u91ca\u653e\u9501\u65f6\uff0c\u53bb\u7a33\u5b9a\u7684\u961f\u5217entry list\u4e2d\u5524\u9192\u961f\u5934\u8282\u70b9\u53bb\u7ade\u4e89\uff0c\u800c\u6b64\u65f6\u88ab\u5524\u9192\u7684\u8282\u70b9\u5e76\u4e0d\u4e00\u5b9a\u80fd\u62a2\u5230\u9501\uff0c\u56e0\u4e3a\u7ebf\u7a0b\u8fdb\u5165cxq\u65f6\u8fd8\u4f1a\u901a\u8fc7\u81ea\u65cb\u6765\u62a2\u9501\uff0c\u4ee5\u6b64\u6765\u5b9e\u73b0\u975e\u516c\u5e73\u9501<\/strong><\/p>\n
\u5982\u679c\u7a33\u5b9a\u7684entry list\u4e2d\u6ca1\u6709\u5b58\u50a8\u7ebf\u7a0b\uff0c\u4f1a\u5c06cxq\u6808\u4e2d\u5b58\u50a8\u7684\u7ebf\u7a0b\u5168\u5b58\u50a8\u5230entry list\u4e2d\u518d\u53bb\u5524\u9192\uff0c\u6b64\u65f6\u8d8a\u665a\u8fdb\u5165cxq\u7684\u7ebf\u7a0b\u53cd\u800c\u4f1a\u8d8a\u65e9\u88ab\u5524\u9192\uff08cxq\u6808\u5148\u8fdb\u540e\u51fa\uff09<\/strong><\/p>\n
\u5176\u5b9e\u5b9e\u73b0\u4e0eAQS\u7c7b\u4f3c\uff0c\u6765\u770b\u8fd9\u6837\u4e00\u6bb5\u4ee3\u7801\uff1a<\/p>\n
t1-t6\u83b7\u53d6\u540c\u4e00\u628a\u9501\uff0c\u4f7f\u7528t1\u7ebf\u7a0b\u8fdb\u884c\u963b\u585e\u4e00\u4f1a\uff0c\u540e\u7eedt2-t6\u7ebf\u7a0b\u6309\u7167\u987a\u5e8f\u542f\u52a8\uff0c\u7531\u4e8e\u81ea\u8f6c\u83b7\u53d6\u4e0d\u5230\u9501\uff0c\u5b83\u4eec\u4f1a\u88ab\u4f9d\u6b21\u653e\u5165cxq\uff1at2,t3,t4,t5,t6<\/code><\/p>\n
\u5728t1\u91ca\u653e\u9501\u65f6\uff0c\u7531\u4e8eentry list\u4e2d\u6ca1\u6709\u7ebf\u7a0b\uff0c\u4e8e\u662f\u5c06cxq\u4e2d\u7684\u7ebf\u7a0b\u5b58\u5165entry list\uff1at6,t5,t4,t3,t2<\/code>\uff0c\u518d\u5524\u9192t6<\/p>\n
\u7531\u4e8e\u540e\u7eed\u6ca1\u6709\u7ebf\u7a0b\u8fdb\u884c\u7ade\u4e89\uff0c\u56e0\u6b64\u6700\u7ec8\u6267\u884c\u987a\u5e8f\u4e3at1,t6,t5,t4,t3,t2<\/code><\/p>\n
Object obj = new Object();\nnew Thread(() -> {\n    synchronized (obj) {\n        try {\n            \/\/\u8f93\u5165\u963b\u585e\n            \/\/\u963b\u585e\u7684\u76ee\u7684\u662f\u8ba9  \u5176\u4ed6\u7ebf\u7a0b\u81ea\u65cb\u5b8c\u672a\u83b7\u53d6\u5230\u9501\uff0c\u8fdb\u5165cxq\u6808\n            System.in.read();\n        } catch (IOException e) {\n            e.printStackTrace();\n        }\n        System.out.println(Thread.currentThread().getName() + " \u83b7\u53d6\u5230\u9501");\n    }\n}, "t1").start();\n\n\/\/sleep\u63a7\u5236\u7ebf\u7a0b\u963b\u585e\u7684\u987a\u5e8f\nThread.sleep(50);\nnew Thread(() -> {\n    synchronized (obj) {\n        System.out.println(Thread.currentThread().getName() + " \u83b7\u53d6\u5230\u9501");\n    }\n}, "t2").start();\n\nThread.sleep(50);\nnew Thread(() -> {\n    synchronized (obj) {\n        System.out.println(Thread.currentThread().getName() + " \u83b7\u53d6\u5230\u9501");\n    }\n}, "t3").start();\n\nThread.sleep(50);\nnew Thread(() -> {\n    synchronized (obj) {\n        System.out.println(Thread.currentThread().getName() + " \u83b7\u53d6\u5230\u9501");\n    }\n}, "t4").start();\n\nThread.sleep(50);\nnew Thread(() -> {\n    synchronized (obj) {\n        System.out.println(Thread.currentThread().getName() + " \u83b7\u53d6\u5230\u9501");\n    }\n}, "t5").start();\n\nThread.sleep(50);\nnew Thread(() -> {\n    synchronized (obj) {\n        System.out.println(Thread.currentThread().getName() + " \u83b7\u53d6\u5230\u9501");\n    }\n}, "t6").start();<\/code><\/pre>\n
\u5927\u81f4\u4e86\u89e3\u4e86\u4e0bobject monitor\uff0c\u6211\u4eec\u518d\u6765\u770b\u770b\u81a8\u80c0\u548c\u81ea\u65cb<\/p>\n
\u81a8\u80c0<\/h5>\n
\u5728\u81a8\u80c0\u65f6\u4f1a\u6709\u56db\u79cd\u72b6\u6001\uff0c\u5206\u522b\u662f<\/p>\n
inflated \u5df2\u81a8\u80c0\uff1amark word\u9501\u6807\u5fd7\u4e3a10\uff082\uff09\u8bf4\u660e\u5df2\u81a8\u80c0\uff0c\u76f4\u63a5\u8fd4\u56deobject monitor<\/p>\n
inflation in progress \u81a8\u80c0\u4e2d\uff1a\u5982\u679c\u5df2\u7ecf\u6709\u5176\u4ed6\u7ebf\u7a0b\u5728\u81a8\u80c0\u4e86\uff0c\u5c31\u7b49\u5f85\u4e00\u4f1a\u5faa\u73af\u540e\u67e5\u770b\u72b6\u6001\u8fdb\u5165\u5df2\u81a8\u80c0\u7684\u903b\u8f91<\/p>\n
stack-locked \u8f7b\u91cf\u7ea7\u9501\u81a8\u80c0<\/p>\n
neutral \u65e0\u9501\u81a8\u80c0<\/p>\n
\u8f7b\u91cf\u7ea7\u9501\u548c\u65e0\u9501\u81a8\u80c0\u903b\u8f91\u5dee\u4e0d\u591a\uff0c\u90fd\u662f\u9700\u8981\u521b\u5efaobject monitor\u5bf9\u8c61\uff0c\u5e76\u4e14set\u4e00\u4e9b\u5c5e\u6027\u8fdb\u53bb<\/strong>\uff08\u6bd4\u5982\uff1amark word\u3001\u9501\u7684\u54ea\u4e2a\u5bf9\u8c61\u3001\u54ea\u4e2a\u7ebf\u7a0b\u6301\u6709\u9501…\uff09\uff0c\u6700\u540e\u518d\u4f7f\u7528CAS\u53bb\u66ff\u6362mark word\u6307\u5411object monitor<\/strong><\/p>\n
ObjectMonitor * ATTR ObjectSynchronizer::inflate (Thread * Self, oop object) {\n\n  for (;;) {\n      const markOop mark = object->mark() ;\n      assert (!mark->has_bias_pattern(), "invariant") ;\n\n      \/\/ The mark can be in one of the following states:\n      \/\/ *  Inflated     - just return\n      \/\/ *  Stack-locked - coerce it to inflated\n      \/\/ *  INFLATING    - busy wait for conversion to complete\n      \/\/ *  Neutral      - aggressively inflate the object.\n      \/\/ *  BIASED       - Illegal.  We should never see this\n\n      \/\/ CASE: inflated \n      \/\/ \u5df2\u81a8\u80c0:\u67e5\u770b mark word \u540e\u4e24\u4f4d\u662f\u5426\u4e3a2  \u662f\u5219\u81a8\u80c0\u5b8c \u8fd4\u56demonitor\u5bf9\u8c61\n      if (mark->has_monitor()) {\n          ObjectMonitor * inf = mark->monitor() ;\n          assert (inf->header()->is_neutral(), "invariant");\n          assert (inf->object() == object, "invariant") ;\n          assert (ObjectSynchronizer::verify_objmon_isinpool(inf), "monitor is invalid");\n          return inf ;\n      }\n\n      \/\/ CASE: inflation in progress - inflating over a stack-lock.\n      \/\/ \u81a8\u80c0\u4e2d: \u7b49\u5f85\u4e00\u4f1a \u518d\u5faa\u73af \u4ece\u81a8\u80c0\u5b8c\u72b6\u6001\u9000\u51fa\n      if (mark == markOopDesc::INFLATING()) {\n         TEVENT (Inflate: spin while INFLATING) ;\n         ReadStableMark(object) ;\n         continue ;\n      }\n\n      \/\/ CASE: stack-locked\n      \/\/\u8f7b\u91cf\u7ea7\u9501\u81a8\u80c0\n      if (mark->has_locker()) {\n          \/\/\u521b\u5efaObjectMonitor\n          ObjectMonitor * m = omAlloc (Self) ;\n          m->Recycle();\n          m->_Responsible  = NULL ;\n          m->OwnerIsThread = 0 ;\n          m->_recursions   = 0 ;\n          m->_SpinDuration = ObjectMonitor::Knob_SpinLimit ;   \/\/ Consider: maintain by type\/class\n          \/\/cas\u5c06mark word\u66ff\u6362\u6307\u5411ObjectMonitor\n          markOop cmp = (markOop) Atomic::cmpxchg_ptr (markOopDesc::INFLATING(), object->mark_addr(), mark) ;         \n          \/\/cas \u5931\u8d25 \u5219\u8bf4\u660e\u5176\u4ed6\u7ebf\u7a0b\u81a8\u80c0\u6210\u529f\uff0c\u5220\u9664\u5f53\u524dmonitor \u9000\u51fa\n          if (cmp != mark) {\n             omRelease (Self, m, true) ;\n             continue ;       \/\/ Interference -- just retry\n          }\n          markOop dmw = mark->displaced_mark_helper() ;\n          assert (dmw->is_neutral(), "invariant") ;\n\n          \/\/\u6210\u529f \u8bbe\u7f6emark word\n          m->set_header(dmw) ;\n          \/\/\u8bbe\u7f6e\u6301\u6709\u9501\u7684\u7ebf\u7a0b\n          m->set_owner(mark->locker());\n          \/\/\u8bbe\u7f6e\u9501\u7684\u662f\u54ea\u4e2a\u5bf9\u8c61\n          m->set_object(object);\n          guarantee (object->mark() == markOopDesc::INFLATING(), "invariant") ;\n          \/\/\u4fee\u6539mark word\u5bf9\u8c61\u5934\u4fe1\u606f \u9501\u72b6\u6001 2\n          object->release_set_mark(markOopDesc::encode(m));\n          if (ObjectMonitor::_sync_Inflations != NULL) ObjectMonitor::_sync_Inflations->inc() ;\n          TEVENT(Inflate: overwrite stacklock) ;\n          if (TraceMonitorInflation) {\n            if (object->is_instance()) {\n              ResourceMark rm;\n              tty->print_cr("Inflating object " INTPTR_FORMAT " , mark " INTPTR_FORMAT " , type %s",\n                (void *) object, (intptr_t) object->mark(),\n                object->klass()->external_name());\n            }\n          }\n          return m ;\n      }\n\n      \/\/ CASE: neutral\n      \/\/\u65e0\u9501\u81a8\u80c0 \u4e0e\u8f7b\u91cf\u7ea7\u9501\u81a8\u80c0\u7c7b\u4f3c\uff0c\u4e5f\u662f\u521b\u5efamonitor\u5bf9\u8c61\u5e76\u6ce8\u5165\u5c5e\u6027\uff0c\u53ea\u662f\u5f88\u591a\u5c5e\u6027\u4e3a\u7a7a\n      assert (mark->is_neutral(), "invariant");\n\n      ObjectMonitor * m = omAlloc (Self) ;\n      m->Recycle();\n      m->set_header(mark);\n      m->set_owner(NULL);\n      m->set_object(object);\n      m->OwnerIsThread = 1 ;\n      m->_recursions   = 0 ;\n      m->_Responsible  = NULL ;\n      m->_SpinDuration = ObjectMonitor::Knob_SpinLimit ;       \/\/ consider: keep metastats by type\/class\n      \/\/cas \u66f4\u65b0 mark word \u5931\u8d25\u5faa\u73af\u7b49\u5f85  \u6210\u529f\u8fd4\u56de\n      if (Atomic::cmpxchg_ptr (markOopDesc::encode(m), object->mark_addr(), mark) != mark) {\n          m->set_object (NULL) ;\n          m->set_owner  (NULL) ;\n          m->OwnerIsThread = 0 ;\n          m->Recycle() ;\n          omRelease (Self, m, true) ;\n          m = NULL ;\n          continue ;\n      }\n     \n      if (ObjectMonitor::_sync_Inflations != NULL) ObjectMonitor::_sync_Inflations->inc() ;\n      TEVENT(Inflate: overwrite neutral) ;\n      if (TraceMonitorInflation) {\n        if (object->is_instance()) {\n          ResourceMark rm;\n          tty->print_cr("Inflating object " INTPTR_FORMAT " , mark " INTPTR_FORMAT " , type %s",\n            (void *) object, (intptr_t) object->mark(),\n            object->klass()->external_name());\n        }\n      }\n      return m ;\n  }\n}<\/code><\/pre>\n
\u81ea\u65cb<\/h5>\n
\u81a8\u80c0\u8fc7\u540e\uff0c\u5728\u6700\u7ec8\u6302\u8d77\u524d\u4f1a\u8fdb\u884c\u56fa\u5b9a\u81ea\u65cb\u548c\u81ea\u9002\u5e94\u81ea\u65cb<\/p>\n
\u56fa\u5b9a\u81ea\u65cb\u9ed8\u8ba410+1\u6b21<\/p>\n
\u81ea\u9002\u5e94\u81ea\u65cb\u4e00\u5f00\u59cb5000\u6b21\uff0c\u5982\u679c\u6700\u8fd1\u7ade\u4e89\u5c11\u83b7\u53d6\u5230\u9501\u5c31\u5c06\u81ea\u65cb\u6b21\u6570\u8c03\u5927\uff0c\u5982\u679c\u6700\u8fd1\u7ade\u4e89\u5927\u83b7\u53d6\u4e0d\u5230\u9501\u5c31\u5c06\u81ea\u65cb\u6b21\u6570\u8c03\u5c0f<\/p>\n
int ObjectMonitor::TrySpin_VaryDuration (Thread * Self) {\n\n    \/\/ Dumb, brutal spin.  Good for comparative measurements against adaptive spinning.\n    int ctr = Knob_FixedSpin ;\n    if (ctr != 0) {\n        while (--ctr >= 0) {\n            if (TryLock (Self) > 0) return 1 ;\n            SpinPause () ;\n        }\n        return 0 ;\n    }\n    \/\/\u5148\u8fdb\u884c\u56fa\u5b9a11\u81ea\u65cb\u6b21\u6570 \u83b7\u53d6\u5230\u9501\u8fd4\u56de\uff0c\u6ca1\u83b7\u53d6\u5230\u7a7a\u8f6c\n    for (ctr = Knob_PreSpin + 1; --ctr >= 0 ; ) {\n      if (TryLock(Self) > 0) {\n        \/\/ Increase _SpinDuration ...\n        \/\/ Note that we don't clamp SpinDuration precisely at SpinLimit.\n        \/\/ Raising _SpurDuration to the poverty line is key.\n        int x = _SpinDuration ;\n        if (x < Knob_SpinLimit) {\n           if (x < Knob_Poverty) x = Knob_Poverty ;\n           _SpinDuration = x + Knob_BonusB ;\n        }\n        return 1 ;\n      }\n      SpinPause () ;\n    }\n    \n    \/\/\u81ea\u9002\u5e94\u81ea\u65cb \u4e00\u5f00\u59cb5000 \u5982\u679c\u6210\u529f\u8ba4\u4e3a\u6b64\u65f6\u7ade\u4e89\u4e0d\u5927 \u81ea\u65cb\u83b7\u53d6\u9501\u6210\u529f\u7387\u9ad8 \u589e\u52a0\u91cd\u8bd5\u6b21\u6570 \u5982\u679c\u5931\u8d25\u5219\u51cf\u5c11\n    \/\/...\n}   <\/code><\/pre>\n
\u603b\u7ed3<\/h3>\n
\u672c\u7bc7\u6587\u7ae0\u56f4\u7ed5synchronized\uff0c\u6df1\u5165\u6d45\u51fa\u7684\u63cf\u8ff0CAS\u3001synchronized\u5728Java\u5c42\u9762\u548cC++\u5c42\u9762\u7684\u5b9e\u73b0\u3001\u9501\u5347\u7ea7\u539f\u7406\u3001\u6848\u4f8b\u3001\u6e90\u7801\u7b49<\/p>\n
synchronized\u7528\u4e8e\u5e76\u53d1\u4e0b\u7684\u9700\u8981\u540c\u6b65\u7684\u573a\u666f\uff0c\u4f7f\u7528\u5b83\u53ef\u4ee5\u6ee1\u8db3\u539f\u5b50\u6027\u3001\u53ef\u89c1\u6027\u4ee5\u53ca\u6709\u5e8f\u6027\uff0c\u5b83\u53ef\u4ee5\u4f5c\u7528\u5728\u666e\u901a\u5bf9\u8c61\u548c\u9759\u6001\u5bf9\u8c61\uff0c\u4f5c\u7528\u4e8e\u9759\u6001\u5bf9\u8c61\u65f6\u662f\u53bb\u83b7\u53d6\u5176\u5bf9\u5e94\u7684Class\u5bf9\u8c61\u7684\u9501<\/strong><\/p>\n
synchronized\u4f5c\u7528\u5728\u4ee3\u7801\u5757\u4e0a\u65f6\uff0c\u4f7f\u7528monitorentry\u3001monitorexit\u5b57\u8282\u7801\u6307\u4ee4\u6765\u6807\u8bc6\u52a0\u9501\u3001\u89e3\u9501\uff1b\u4f5c\u7528\u5728\u65b9\u6cd5\u4e0a\u65f6\uff0c\u5728\u8bbf\u95ee\u6807\u8bc6\u52a0\u9501synchronized\u5173\u952e\u5b57\uff0c\u865a\u62df\u673a\u9690\u5f0f\u4f7f\u7528monitorentry\u3001monitorexit<\/strong><\/p>\n
CAS \u6bd4\u8f83\u5e76\u66ff\u6362\uff0c\u5e38\u4e0e\u91cd\u8bd5\u673a\u5236\u5b9e\u73b0\u4e50\u89c2\u9501\/\u81ea\u65cb\u9501\uff0c\u4f18\u70b9\u662f\u80fd\u591f\u5728\u7ade\u4e89\u5c0f\u7684\u573a\u666f\u7528\u8f83\u5c0f\u7684\u5f00\u9500\u53d6\u4ee3\u7ebf\u7a0b\u6302\u8d77\uff0c\u4f46\u5e26\u6765ABA\u95ee\u9898\u3001\u65e0\u6cd5\u9884\u4f30\u91cd\u8bd5\u6b21\u6570\u7a7a\u8f6cCPU\u7684\u5f00\u9500\u7b49\u95ee\u9898<\/strong><\/p>\n
\u8f7b\u91cf\u7ea7\u9501\u7684\u63d0\u51fa\u662f\u4e3a\u4e86\u5728\u4ea4\u66ff\u6267\u884c\/\u7ade\u4e89\u5c11\u7684\u573a\u666f\uff0c\u7528\u66f4\u5c0f\u7684\u5f00\u9500\u53d6\u4ee3\u4e92\u65a5\u91cf\uff1b\u4f7f\u7528CAS\u548clock record\u5b9e\u73b0<\/strong><\/p>\n
\u8f7b\u91cf\u7ea7\u9501\u52a0\u9501\u65f6\uff0c\u5982\u679c\u662f\u65e0\u9501\u5219\u590d\u5236mark word\u5230lock record\u4e2d\uff0c\u518dCAS\u5c06\u5bf9\u8c61mark word\u66ff\u6362\u4e3a\u6307\u5411\u8be5lock record\uff0c\u5931\u8d25\u5219\u81a8\u80c0\uff1b\u5982\u679c\u5df2\u7ecf\u6301\u6709\u9501\u5219\u5224\u65ad\u6301\u6709\u9501\u7684\u7ebf\u7a0b\u662f\u4e0d\u662f\u5f53\u524d\u7ebf\u7a0b\uff0c\u662f\u5219\u7d2f\u52a0\u6b21\u6570\uff0c\u4e0d\u662f\u5f53\u524d\u7ebf\u7a0b\u5219\u81a8\u80c0<\/strong><\/p>\n
\u8f7b\u91cf\u7ea7\u9501\u89e3\u9501\u65f6\uff0c\u67e5\u770block record\u590d\u5236\u7684\u662f\u4e0d\u662fnull\uff0c\u662f\u5219\u8bf4\u660e\u662f\u53ef\u91cd\u5165\u9501\uff0c\u6b21\u6570\u51cf\u4e00\uff1b\u4e0d\u662f\u5219CAS\u628a\u590d\u5236\u8fc7\u6765\u7684mark word\u66ff\u6362\u56de\u53bb\uff0c\u5982\u679c\u66ff\u6362\u5931\u8d25\u8bf4\u660e\u5176\u4ed6\u7ebf\u7a0b\u7ade\u4e89\uff0cmark word\u5df2\u7ecf\u6307\u5411object monitor\uff0c\u53bb\u6307\u5411\u91cd\u91cf\u7ea7\u9501\u7684\u91ca\u653e<\/strong><\/p>\n
\u504f\u5411\u9501\u7684\u63d0\u51fa\u662f\u4e3a\u4e86\u5728\u7ecf\u5e38\u4e00\u6761\u7ebf\u7a0b\u6267\u884c\u7684\u573a\u666f\u4e0b\uff0c\u7528\u66f4\u5c0f\u7684\u5f00\u9500\u6765\u53d6\u4ee3CAS\u7684\u5f00\u9500\uff0c\u53ea\u4e0d\u8fc7\u9ad8\u7248\u672c\u4e0d\u518d\u9ed8\u8ba4\u5f00\u542f<\/strong><\/p>\n
\u91cd\u91cf\u7ea7\u9501\u7531object monitor\u6765\u5b9e\u73b0\uff0cobject monitor\u4e2d\u4f7f\u7528cxq\u3001entry list\u6765\u6784\u6210\u963b\u585e\u961f\u5217\uff0cwait set\u6765\u6784\u6210\u7b49\u5f85\u961f\u5217<\/strong><\/p>\n
\u5f53\u6267\u884cwait\u65b9\u6cd5\u65f6\uff0c\u7ebf\u7a0b\u6784\u5efa\u4e3a\u8282\u70b9\u52a0\u5165wait set\uff1b\u5f53\u6267\u884cnotify\u65b9\u6cd5\u65f6\uff0c\u5c06wait set\u961f\u5934\u8282\u70b9\u52a0\u5165cxq\uff0c\u5728\u91ca\u653e\u9501\u65f6\u624d\u53bb\u5524\u9192entry list\u961f\u5934\u8282\u70b9\u7ade\u4e89\u9501\uff0c\u5373\u4f7f\u6ca1\u62a2\u5230\u9501\u6784\u5efa\u4e3a\u8282\u70b9\u52a0\u5165cxq\u65f6\u8fd8\u4f1a\u81ea\u65cb\uff0c\u56e0\u6b64\u5e76\u4e0d\u662fentry list\u961f\u5934\u8282\u70b9\u5c31\u4e00\u5b9a\u80fd\u62a2\u5230\u9501\uff0c\u4ee5\u6b64\u6765\u5b9e\u73b0\u975e\u516c\u5e73\u9501\uff1b\u5f53entry list\u4e3a\u7a7a\u65f6\uff0c\u5c06cxq\u6808\u4e2d\u7684\u8282\u70b9\u52a0\u5165entry list\u961f\u5217\uff08\u540e\u8fdb\u5165cxq\u7684\u8282\u70b9\u4f1a\u88ab\u5148\u5524\u9192\uff09<\/strong><\/p>\n
\u5728\u81a8\u80c0\u4e3a\u91cd\u91cf\u7ea7\u9501\u65f6\u6709\u56db\u79cd\u60c5\u51b5\uff0c\u5982\u679c\u72b6\u6001\u4e3a\u5df2\u81a8\u80c0\u5219\u76f4\u63a5\u8fd4\u56deobject monitor\u5bf9\u8c61\uff1b\u5982\u679c\u72b6\u6001\u4e3a\u81a8\u80c0\u4e2d\uff0c\u8bf4\u660e\u5176\u4ed6\u7ebf\u7a0b\u6b63\u5728\u81a8\u80c0\uff0c\u7b49\u5f85\u4f1a\uff0c\u4e0b\u6b21\u5faa\u73af\u8fdb\u5165\u5df2\u81a8\u80c0\u7684\u903b\u8f91\uff1b\u5982\u679c\u72b6\u6001\u4e3a\u8f7b\u91cf\u7ea7\u9501\u81a8\u80c0\u6216\u65e0\u9501\u81a8\u80c0\uff0c\u90fd\u4f1a\u53bb\u521b\u5efaobject monitor\u5bf9\u8c61\uff0cset\u4e00\u4e9b\u91cd\u8981\u5c5e\u6027\uff0c\u5e76CAS\u53bb\u5c06mark word\u66ff\u6362\u4e3a\u6307\u5411\u8be5object monitor<\/strong><\/p>\n
\u91cd\u91cf\u7ea7\u9501\u5728\u6700\u7ec8\u6302\u8d77\u524d\u4f1a\u8fdb\u884c\u56fa\u5b9a\u81ea\u65cb\u548c\u81ea\u9002\u5e94\u81ea\u65cb\uff08\u6700\u8fd1\u7ade\u4e89\u5c0f\u5c31\u589e\u52a0\u81ea\u65cb\u6b21\u6570\uff1b\u7ade\u4e89\u591a\u5c31\u51cf\u5c11\u81ea\u65cb\u6b21\u6570\uff09<\/strong><\/p>\n
\u6700\u540e\uff08\u4e0d\u8981\u767d\u5ad6\uff0c\u4e00\u952e\u4e09\u8fde\u6c42\u6c42\u62c9~\uff09<\/h3>\n
\u672c\u7bc7\u6587\u7ae0\u88ab\u6536\u5165\u4e13\u680f \u7531\u70b9\u5230\u7ebf\uff0c\u7531\u7ebf\u5230\u9762\uff0c\u6df1\u5165\u6d45\u51fa\u6784\u5efaJava\u5e76\u53d1\u7f16\u7a0b\u77e5\u8bc6\u4f53\u7cfb<\/a>\uff0c\u611f\u5174\u8da3\u7684\u540c\u5b66\u53ef\u4ee5\u6301\u7eed\u5173\u6ce8\u5594<\/p>\n
\u672c\u7bc7\u6587\u7ae0\u7b14\u8bb0\u4ee5\u53ca\u6848\u4f8b\u88ab\u6536\u5165 gitee-StudyJava<\/a>\u3001 github-StudyJava<\/a> \u611f\u5174\u8da3\u7684\u540c\u5b66\u53ef\u4ee5stat\u4e0b\u6301\u7eed\u5173\u6ce8\u5594~<\/p>\n
\u6848\u4f8b\u5730\u5740\uff1a<\/p>\n
Gitee-JavaConcurrentProgramming\/src\/main\/java\/B_synchronized<\/a><\/p>\n
Github-JavaConcurrentProgramming\/src\/main\/java\/B_synchronized<\/a><\/p>\n
\u6709\u4ec0\u4e48\u95ee\u9898\u53ef\u4ee5\u5728\u8bc4\u8bba\u533a\u4ea4\u6d41\uff0c\u5982\u679c\u89c9\u5f97\u83dc\u83dc\u5199\u7684\u4e0d\u9519\uff0c\u53ef\u4ee5\u70b9\u8d5e\u3001\u5173\u6ce8\u3001\u6536\u85cf\u652f\u6301\u4e00\u4e0b~<\/p>\n
\u5173\u6ce8\u83dc\u83dc\uff0c\u5206\u4eab\u66f4\u591a\u5e72\u8d27\uff0c\u516c\u4f17\u53f7\uff1a\u83dc\u83dc\u7684\u540e\u7aef\u79c1\u623f\u83dc<\/p>\n
https:\/\/segmentfault.com\/a\/1190000044189342<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
Synchronized \u672c\u7bc7\u6587\u7ae0\u5c06\u56f4\u7ed5synchronized\u5173\u952e\u5b57\uff0c\u4f7f\u7528\u5927\u91cf\u56fe\u7247\u3001\u6848\u4f8b\u6df1\u5165\u6d45\u51fa\u7684\u63cf\u8ff0CAS […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10008246","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008246","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10008246"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008246\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10008246"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10008246"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10008246"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}