{"id":10006141,"date":"2022-08-09T00:29:30","date_gmt":"2022-08-08T16:29:30","guid":{"rendered":"https:\/\/ityet.com\/?p=10006141"},"modified":"2022-08-09T00:29:30","modified_gmt":"2022-08-08T16:29:30","slug":"2-5w-%e5%ad%97%e8%af%a6%e8%a7%a3%e7%ba%bf%e7%a8%8b%e4%b8%8e%e9%94%81%e4%ba%86%ef%bc%8c%e9%9d%a2%e8%af%95%e9%9a%8f%e4%be%bf%e9%97%ae%ef%bc%81%ef%bc%81","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10006141","title":{"rendered":"2.5W \u5b57\u8be6\u89e3\u7ebf\u7a0b\u4e0e\u9501\u4e86\uff0c\u9762\u8bd5\u968f\u4fbf\u95ee\uff01\uff01"},"content":{"rendered":"<p>\u5728 java \u5e76\u53d1\u7f16\u7a0b\u4e2d\uff0c\u7ebf\u7a0b\u548c\u9501\u6c38\u8fdc\u662f\u6700\u91cd\u8981\u7684\u6982\u5ff5\u3002\u8bed\u8a00\u89c4\u8303\u867d\u7136\u662f\u89c4\u8303\u63cf\u8ff0\uff0c\u4f46\u662f\u5176\u4e2d\u4e5f\u6709\u975e\u5e38\u591a\u7684\u77e5\u8bc6\u548c\u6700\u4f73\u5b9e\u8df5\u662f\u503c\u5f97\u5b66\u4e60\u7684\uff0c\u76f8\u4fe1\u8fd9\u7bc7\u6587\u7ae0\u8fd8\u662f\u53ef\u4ee5\u7ed9\u5f88\u591a\u8bfb\u8005\u63d0\u4f9b\u5b66\u4e60\u53c2\u8003\u7684\u3002<\/p>\n<p>\u672c\u6587\u4e3b\u8981\u662f<strong>\u7ffb\u8bd1 + \u89e3\u91ca<\/strong> Oracle <strong>\u300aThe Java Language Specification, Java SE 8 Edition\u300b<\/strong> \u7684\u7b2c17\u7ae0 <strong>\u300aThreads and Locks\u300b<\/strong> \uff0c\u539f\u6587\u5927\u698230\u9875pdf\uff0c\u6211\u52a0\u5165\u4e86\u5f88\u591a\u81ea\u5df1\u7684\u7406\u89e3\uff0c\u5e0c\u671b\u80fd\u5e2e\u5927\u5bb6\u628a\u89c4\u8303\u770b\u61c2\uff0c\u5e76\u4e14\u4ece\u4e2d\u5f97\u5230\u5f88\u591a\u4f60\u4e00\u76f4\u60f3\u8981\u77e5\u9053\u4f46\u662f\u8fd8\u4e0d\u77e5\u9053\u7684\u77e5\u8bc6\u3002<\/p>\n<p>\u6ce8\u610f\uff0c\u672c\u6587\u5728\u8bf4 Java \u8bed\u8a00\u89c4\u8303\uff0c\u4e0d\u662f JVM \u89c4\u8303\uff0cJVM \u7684\u5b9e\u73b0\u9700\u8981\u6ee1\u8db3\u8bed\u8a00\u89c4\u8303\u4e2d\u5b9a\u4e49\u7684\u5185\u5bb9\uff0c\u4f46\u662f\u5177\u4f53\u7684\u5b9e\u73b0\u7ec6\u8282\u7531\u5404 JVM \u5382\u5546\u81ea\u5df1\u6765\u51b3\u5b9a\u3002\u6240\u4ee5\uff0c\u8bed\u8a00\u89c4\u8303\u8981\u5c3d\u53ef\u80fd\u4e25\u8c28\u5168\u9762\uff0c\u4f46\u662f\u4e5f\u4e0d\u80fd\u9650\u5236\u8fc7\u591a\uff0c\u4e0d\u7136\u4f1a\u9650\u5236 JVM \u5382\u5546\u5bf9\u5f88\u591a\u7ec6\u8282\u8fdb\u884c\u6027\u80fd\u4f18\u5316\u3002<\/p>\n<p>\u6211\u80fd\u529b\u6709\u9650\uff0c\u867d\u7136\u5df2\u7ecf\u5f88\u7528\u5fc3\u4e86\uff0c\u4f46\u6709\u4e9b\u5730\u65b9\u6211\u771f\u7684\u4e0d\u61c2\uff0c\u6211\u5df2\u7ecf\u5728\u6587\u4e2d\u6807\u8bb0\u51fa\u6765\u4e86\u3002<\/p>\n<p>\u5efa\u8bae\u5206 3 \u90e8\u5206\u9605\u8bfb\u3002<\/p>\n<ul>\n<li>\u5c06 17.1\u300117.2\u300117.3 \u4e00\u8d77\u9605\u8bfb\uff0c\u8fd9\u91cc\u5173\u4e8e\u7ebf\u7a0b\u4e2d\u7684 wait\u3001notify\u3001\u4e2d\u65ad\u6709\u5f88\u591a\u7684\u77e5\u8bc6\uff1b<\/li>\n<li>17.4 \u7684\u5185\u5b58\u6a21\u578b\u6bd4\u8f83\u957f\uff0c\u91cd\u6392\u5e8f\u548c happens-before \u5173\u7cfb\u662f\u91cd\u70b9\uff1b<\/li>\n<li>\u5269\u4e0b\u7684 final\u3001\u5b57\u5206\u88c2\u3001double\u548clong\u7684\u975e\u539f\u5b50\u95ee\u9898\uff0c\u8fd9\u4e9b\u90fd\u662f\u76f8\u5bf9\u72ec\u7acb\u7684 topic\u3002<\/li>\n<\/ul>\n<h2>Chapter 17. Threads and Locks<\/h2>\n<h3>\u524d\u8a00<\/h3>\n<p>\u5728 java \u4e2d\uff0c\u7ebf\u7a0b\u7531 Thread \u7c7b\u8868\u793a\uff0c\u7528\u6237\u521b\u5efa\u7ebf\u7a0b\u7684\u552f\u4e00\u65b9\u5f0f\u662f\u521b\u5efa Thread \u7c7b\u7684\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u6bcf\u4e00\u4e2a\u7ebf\u7a0b\u90fd\u548c\u8fd9\u6837\u7684\u4e00\u4e2a\u5b9e\u4f8b\u5173\u8054\u3002\u5728\u76f8\u5e94\u7684 Thread \u5b9e\u4f8b\u4e0a\u8c03\u7528 start() \u65b9\u6cd5\u5c06\u542f\u52a8\u4e00\u4e2a\u7ebf\u7a0b\u3002<\/p>\n<p>\u5982\u679c\u6ca1\u6709\u6b63\u786e\u4f7f\u7528\u540c\u6b65\uff0c\u7ebf\u7a0b\u8868\u73b0\u51fa\u6765\u7684\u73b0\u8c61\u5c06\u4f1a\u662f\u4ee4\u4eba\u7591\u60d1\u7684\u3001\u8fdd\u53cd\u76f4\u89c9\u7684\u3002\u8fd9\u4e2a\u7ae0\u8282\u5c06\u63cf\u8ff0\u591a\u7ebf\u7a0b\u7f16\u7a0b\u7684\u8bed\u4e49\u95ee\u9898\uff0c\u5305\u62ec\u4e00\u7cfb\u5217\u7684\u89c4\u5219\uff0c\u8fd9\u4e9b\u89c4\u5219\u5b9a\u4e49\u4e86<strong>\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e2d\u7ebf\u7a0b\u5bf9\u5171\u4eab\u5185\u5b58\u4e2d\u503c\u7684\u4fee\u6539\u662f\u5426\u5bf9\u5176\u4ed6\u7ebf\u7a0b\u7acb\u5373\u53ef\u89c1<\/strong>\u3002<\/p>\n<p>java\u7f16\u7a0b\u8bed\u8a00\u5185\u5b58\u6a21\u578b\u5b9a\u4e49\u4e86\u7edf\u4e00\u7684\u5185\u5b58\u6a21\u578b\u7528\u4e8e\u5c4f\u853d\u4e0d\u540c\u7684\u786c\u4ef6\u67b6\u6784\uff0c\u5728\u6ca1\u6709\u6b67\u4e49\u7684\u60c5\u51b5\u4e0b\uff0c\u4e0b\u9762\u5c06\u7528<strong>\u5185\u5b58\u6a21\u578b<\/strong>\u8868\u793a\u8fd9\u4e2a\u6982\u5ff5\u3002<\/p>\n<p>\u8fd9\u4e9b\u8bed\u4e49\u6ca1\u6709\u89c4\u5b9a\u591a\u7ebf\u7a0b\u7684\u7a0b\u5e8f\u5728 JVM \u7684\u5b9e\u73b0\u4e0a\u5e94\u8be5\u600e\u4e48\u6267\u884c\uff0c\u800c\u662f\u9650\u5b9a\u4e86\u4e00\u7cfb\u5217\u89c4\u5219\uff0c\u7531 JVM \u5382\u5546\u6765\u6ee1\u8db3\u8fd9\u4e9b\u89c4\u5219\uff0c\u5373\u4e0d\u7ba1 JVM \u7684\u6267\u884c\u7b56\u7565\u662f\u4ec0\u4e48\uff0c\u8868\u73b0\u51fa\u6765\u7684\u884c\u4e3a\u5fc5\u987b\u662f\u53ef\u88ab\u63a5\u53d7\u7684\u3002<\/p>\n<blockquote><p>\u64cd\u4f5c\u7cfb\u7edf\u6709\u81ea\u5df1\u7684\u5185\u5b58\u6a21\u578b\uff0cC\/C++ \u8fd9\u4e9b\u8bed\u8a00\u76f4\u63a5\u4f7f\u7528\u7684\u5c31\u662f\u64cd\u4f5c\u7cfb\u7edf\u7684\u5185\u5b58\u6a21\u578b\uff0c\u800c Java \u4e3a\u4e86\u5c4f\u853d\u5404\u4e2a\u7cfb\u7edf\u7684\u5dee\u5f02\uff0c\u5b9a\u4e49\u4e86\u81ea\u5df1\u7684\u7edf\u4e00\u7684\u5185\u5b58\u6a21\u578b\u3002\u7b80\u5355\u8bf4\uff0cJava \u5f00\u53d1\u8005\u4e0d\u518d\u5173\u5fc3\u6bcf\u4e2a CPU \u6838\u5fc3\u6709\u81ea\u5df1\u7684\u5185\u5b58\uff0c\u7136\u540e\u5171\u4eab\u4e3b\u5185\u5b58\u3002\u800c\u662f\u628a\u5173\u6ce8\u70b9\u8f6c\u79fb\u5230\uff1a\u6bcf\u4e2a\u7ebf\u7a0b\u90fd\u6709\u81ea\u5df1\u7684\u5de5\u4f5c\u5185\u5b58\uff0c\u6240\u6709\u7ebf\u7a0b\u5171\u4eab\u4e3b\u5185\u5b58\u3002<\/p><\/blockquote>\n<h3>17.1 \u540c\u6b65\uff08synchronization\uff09<\/h3>\n<p>Java \u63d0\u4f9b\u4e86\u591a\u79cd\u7ebf\u7a0b\u4e4b\u95f4\u901a\u4fe1\u7684\u673a\u5236\uff0c\u5176\u4e2d\u6700\u57fa\u672c\u7684\u5c31\u662f\u4f7f\u7528\u540c\u6b65 (synchronization)\uff0c\u5176\u4f7f\u7528\u76d1\u89c6\u5668 (monitor) \u6765\u5b9e\u73b0\u3002java\u4e2d\u7684<strong>\u6bcf\u4e2a\u5bf9\u8c61\u90fd\u5173\u8054\u4e86\u4e00\u4e2a\u76d1\u89c6\u5668<\/strong>\uff0c\u7ebf\u7a0b\u53ef\u4ee5\u5bf9\u5176\u8fdb\u884c\u52a0\u9501\u548c\u89e3\u9501\u64cd\u4f5c\u3002<\/p>\n<p>\u5728\u540c\u4e00\u65f6\u95f4\uff0c\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u53ef\u4ee5\u62ff\u5230\u5bf9\u8c61\u4e0a\u7684\u76d1\u89c6\u5668\u9501\u3002\u5982\u679c\u5176\u4ed6\u7ebf\u7a0b\u5728\u9501\u88ab\u5360\u7528\u671f\u95f4\u8bd5\u56fe\u53bb\u83b7\u53d6\u9501\uff0c\u90a3\u4e48\u5c06\u4f1a\u88ab\u963b\u585e\u76f4\u5230\u6210\u529f\u83b7\u53d6\u5230\u9501\u3002\u540c\u65f6\uff0c\u76d1\u89c6\u5668\u9501\u53ef\u4ee5\u91cd\u5165\uff0c\u4e5f\u5c31\u662f\u8bf4\u5982\u679c\u7ebf\u7a0b t \u62ff\u5230\u4e86\u9501\uff0c\u90a3\u4e48\u7ebf\u7a0b t \u53ef\u4ee5\u5728\u89e3\u9501\u4e4b\u524d\u91cd\u590d\u83b7\u53d6\u9501\uff1b\u6bcf\u6b21\u89e3\u9501\u64cd\u4f5c\u4f1a\u53cd\u8f6c\u4e00\u6b21\u52a0\u9501\u4ea7\u751f\u7684\u6548\u679c\u3002<\/p>\n<p>synchronized \u6709\u4ee5\u4e0b\u4e24\u79cd\u4f7f\u7528\u65b9\u5f0f\uff1a<\/p>\n<ul>\n<li>synchronized \u4ee3\u7801\u5757\u3002synchronized(object)\u5728\u5bf9\u67d0\u4e2a\u5bf9\u8c61\u4e0a\u6267\u884c\u52a0\u9501\u65f6\uff0c\u4f1a\u5c1d\u8bd5\u5728\u8be5\u5bf9\u8c61\u7684\u76d1\u89c6\u5668\u4e0a\u8fdb\u884c\u52a0\u9501\u64cd\u4f5c\uff0c\u53ea\u6709\u6210\u529f\u83b7\u53d6\u9501\u4e4b\u540e\uff0c\u7ebf\u7a0b\u624d\u4f1a\u7ee7\u7eed\u5f80\u4e0b\u6267\u884c\u3002\u7ebf\u7a0b\u83b7\u53d6\u5230\u4e86\u76d1\u89c6\u5668\u9501\u540e\uff0c\u5c06\u7ee7\u7eed\u6267\u884csynchronized \u4ee3\u7801\u5757\u4e2d\u7684\u4ee3\u7801\uff0c\u5982\u679c\u4ee3\u7801\u5757\u6267\u884c\u5b8c\u6210\uff0c\u6216\u8005\u629b\u51fa\u4e86\u5f02\u5e38\uff0c\u7ebf\u7a0b\u5c06\u4f1a\u81ea\u52a8\u5bf9\u8be5\u5bf9\u8c61\u4e0a\u7684\u76d1\u89c6\u5668\u6267\u884c\u89e3\u9501\u64cd\u4f5c\u3002<\/li>\n<li>synchronized \u4f5c\u7528\u4e8e\u65b9\u6cd5\uff0c\u79f0\u4e3a\u540c\u6b65\u65b9\u6cd5\u3002\u540c\u6b65\u65b9\u6cd5\u88ab\u8c03\u7528\u65f6\uff0c\u4f1a\u81ea\u52a8\u6267\u884c\u52a0\u9501\u64cd\u4f5c\uff0c\u53ea\u6709\u52a0\u9501\u6210\u529f\uff0c\u65b9\u6cd5\u4f53\u624d\u4f1a\u5f97\u5230\u6267\u884c\u3002\u5982\u679c\u88ab synchronized \u4fee\u9970\u7684\u65b9\u6cd5\u662f\u5b9e\u4f8b\u65b9\u6cd5\uff0c\u90a3\u4e48<strong>\u8fd9\u4e2a\u5b9e\u4f8b\u7684\u76d1\u89c6\u5668<\/strong>\u4f1a\u88ab\u9501\u5b9a\u3002\u5982\u679c\u662f static \u65b9\u6cd5\uff0c\u7ebf\u7a0b\u4f1a\u9501\u4f4f\u76f8\u5e94\u7684 <strong>Class \u5bf9\u8c61\u7684\u76d1\u89c6\u5668<\/strong>\u3002\u65b9\u6cd5\u4f53\u6267\u884c\u5b8c\u6210\u6216\u8005\u5f02\u5e38\u9000\u51fa\u540e\uff0c\u4f1a\u81ea\u52a8\u6267\u884c\u89e3\u9501\u64cd\u4f5c\u3002<\/li>\n<\/ul>\n<p>Java\u8bed\u8a00\u89c4\u8303\u65e2\u4e0d\u8981\u6c42\u963b\u6b62\u6b7b\u9501\u7684\u53d1\u751f\uff0c\u4e5f\u4e0d\u8981\u6c42\u68c0\u6d4b\u5230\u6b7b\u9501\u7684\u53d1\u751f\u3002\u5982\u679c\u7ebf\u7a0b\u8981\u5728\u591a\u4e2a\u5bf9\u8c61\u4e0a\u6267\u884c\u52a0\u9501\u64cd\u4f5c\uff0c\u90a3\u4e48\u5c31\u5e94\u8be5\u4f7f\u7528\u4f20\u7edf\u7684\u65b9\u6cd5\u6765\u907f\u514d\u6b7b\u9501\u7684\u53d1\u751f\uff0c\u5982\u679c\u6709\u5fc5\u8981\u7684\u8bdd\uff0c\u9700\u8981\u521b\u5efa\u66f4\u9ad8\u5c42\u6b21\u7684\u4e0d\u4f1a\u4ea7\u751f\u6b7b\u9501\u7684\u52a0\u9501\u539f\u8bed\u3002<\/p>\n<p>java \u8fd8\u63d0\u4f9b\u4e86\u5176\u4ed6\u7684\u4e00\u4e9b\u540c\u6b65\u673a\u5236\uff0c\u6bd4\u5982\u5bf9 volatile \u53d8\u91cf\u7684\u8bfb\u5199\u3001\u4f7f\u7528 java.util.concurrent \u5305\u4e2d\u7684\u540c\u6b65\u5de5\u5177\u7c7b\u7b49\u3002<\/p>\n<blockquote>\n<p><strong>\u540c\u6b65<\/strong>\u8fd9\u4e00\u8282\u8bf4\u4e86 Java \u5e76\u53d1\u7f16\u7a0b\u4e2d\u6700\u57fa\u7840\u7684 synchronized \u8fd9\u4e2a\u5173\u952e\u5b57\uff0c\u5927\u5bb6\u4e00\u5b9a\u8981\u7406\u89e3 synchronize \u7684\u9501\u662f\u4ec0\u4e48\uff0c\u5b83\u7684\u9501\u662f\u57fa\u4e8e Java \u5bf9\u8c61\u7684\u76d1\u89c6\u5668 monitor\uff0c\u6240\u4ee5\u4efb\u4f55\u5bf9\u8c61\u90fd\u53ef\u4ee5\u7528\u6765\u505a\u9501\u3002\u6709\u5174\u8da3\u7684\u8bfb\u8005\u53ef\u4ee5\u53bb\u4e86\u89e3\u76f8\u5173\u77e5\u8bc6\uff0c\u5305\u62ec\u504f\u5411\u9501\u3001\u8f7b\u91cf\u7ea7\u9501\u3001\u91cd\u91cf\u7ea7\u9501\u7b49\u3002<\/p>\n<p>\u5c0f\u77e5\u8bc6\u70b9\uff1a<strong>\u5bf9 Class \u5bf9\u8c61\u52a0\u9501\u3001\u5bf9\u5bf9\u8c61\u52a0\u9501\uff0c\u5b83\u4eec\u4e4b\u95f4\u4e0d\u6784\u6210\u540c\u6b65<\/strong>\u3002synchronized \u4f5c\u7528\u4e8e\u9759\u6001\u65b9\u6cd5\u65f6\u662f\u5bf9 <strong>Class \u5bf9\u8c61<\/strong>\u52a0\u9501\uff0c\u4f5c\u7528\u4e8e\u5b9e\u4f8b\u65b9\u6cd5\u65f6\u662f\u5bf9\u5b9e\u4f8b\u52a0\u9501\u3002<\/p>\n<p>\u9762\u8bd5\u4e2d\u7ecf\u5e38\u4f1a\u95ee\u5230\u4e00\u4e2a\u7c7b\u4e2d\u7684\u4e24\u4e2a synchronized static \u65b9\u6cd5\u4e4b\u95f4\u662f\u5426\u6784\u6210\u540c\u6b65\uff1f\u6784\u6210\u540c\u6b65\u3002<\/p>\n<\/blockquote>\n<h3>17.2 \u7b49\u5f85\u96c6\u5408 \u548c \u5524\u9192\uff08Wait Sets and Notification\uff09<\/h3>\n<p>\u6bcf\u4e2a java \u5bf9\u8c61\uff0c\u90fd\u5173\u8054\u4e86\u4e00\u4e2a\u76d1\u89c6\u5668\uff0c\u4e5f\u5173\u8054\u4e86\u4e00\u4e2a<strong>\u7b49\u5f85\u96c6\u5408<\/strong>\u3002\u7b49\u5f85\u96c6\u5408\u662f\u4e00\u4e2a\u7ebf\u7a0b\u96c6\u5408\u3002<\/p>\n<p>\u5f53\u5bf9\u8c61\u88ab\u521b\u5efa\u51fa\u6765\u65f6\uff0c\u5b83\u7684\u7b49\u5f85\u96c6\u5408\u662f\u7a7a\u7684\uff0c\u5bf9\u4e8e\u5411\u7b49\u5f85\u96c6\u5408\u4e2d\u6dfb\u52a0\u6216\u8005\u79fb\u9664\u7ebf\u7a0b\u7684\u64cd\u4f5c\u90fd\u662f\u539f\u5b50\u7684\uff0c\u4ee5\u4e0b\u51e0\u4e2a\u64cd\u4f5c\u53ef\u4ee5\u64cd\u7eb5\u8fd9\u4e2a\u7b49\u5f85\u96c6\u5408\uff1aObject.wait, Object.notify, Object.notifyAll\u3002<\/p>\n<p>\u7b49\u5f85\u96c6\u5408\u4e5f\u53ef\u80fd\u53d7\u5230\u7ebf\u7a0b\u7684\u4e2d\u65ad\u72b6\u6001\u7684\u5f71\u54cd\uff0c\u4e5f\u53d7\u5230\u7ebf\u7a0b\u4e2d\u5904\u7406\u4e2d\u65ad\u7684\u65b9\u6cd5\u7684\u5f71\u54cd\u3002\u53e6\u5916\uff0csleep \u65b9\u6cd5\u548c join \u65b9\u6cd5\u53ef\u4ee5\u611f\u77e5\u5230\u7ebf\u7a0b\u7684 wait \u548c notify\u3002<\/p>\n<p>\u8fd9\u91cc\u6982\u62ec\u5f97\u6bd4\u8f83\u7b80\u7565\uff0c\u6ca1\u770b\u61c2\u7684\u8bfb\u8005\u6ca1\u5173\u7cfb\uff0c\u7ee7\u7eed\u5f80\u4e0b\u770b\u5c31\u662f\u4e86\u3002<\/p>\n<p>\u8fd9\u8282\u8981\u8bb2Java\u7ebf\u7a0b\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u4e3b\u8981\u5305\u62ec\uff1a<\/p>\n<ul>\n<li>Thread \u4e2d\u7684 sleep\u3001join\u3001interrupt<\/li>\n<li>\u7ee7\u627f\u81ea Object \u7684 wait\u3001notify\u3001notifyAll<\/li>\n<li>\u8fd8\u6709 Java \u7684\u4e2d\u65ad\uff0c\u8fd9\u4e2a\u6982\u5ff5\u4e5f\u5f88\u91cd\u8981<\/li>\n<\/ul>\n<h4>17.2.1 \u7b49\u5f85 \uff08Wait\uff09<\/h4>\n<p>\u7b49\u5f85\u64cd\u4f5c\u7531\u4ee5\u4e0b\u51e0\u4e2a\u65b9\u6cd5\u5f15\u53d1\uff1await()\uff0cwait(long millisecs)\uff0cwait(long millisecs, int nanosecs)\u3002\u5728\u540e\u9762\u4e24\u4e2a\u91cd\u8f7d\u65b9\u6cd5\u4e2d\uff0c\u5982\u679c\u53c2\u6570\u4e3a 0\uff0c\u5373 wait(0)\u3001wait(0, 0) \u548c wait() \u662f\u7b49\u6548\u7684\u3002<\/p>\n<p>\u5982\u679c\u8c03\u7528 wait \u65b9\u6cd5\u65f6\u6ca1\u6709\u629b\u51fa InterruptedException \u5f02\u5e38\uff0c\u5219\u8868\u793a\u6b63\u5e38\u8fd4\u56de\u3002<\/p>\n<blockquote><p>\u524d\u65b9\u9ad8\u80fd\uff0c\u8bf7\u8bfb\u8005\u4fdd\u6301\u9ad8\u5ea6\u7cbe\u795e\u96c6\u4e2d\u3002<\/p><\/blockquote>\n<p>\u6211\u4eec\u5728\u7ebf\u7a0b t \u4e2d\u5bf9\u5bf9\u8c61 m \u8c03\u7528 m.wait() \u65b9\u6cd5\uff0cn \u4ee3\u8868\u52a0\u9501\u7f16\u53f7\uff0c\u540c\u65f6\u8fd8\u6ca1\u6709\u76f8\u5339\u914d\u7684\u89e3\u9501\u64cd\u4f5c\uff0c\u5219\u4e0b\u9762\u7684\u5176\u4e2d\u4e4b\u4e00\u4f1a\u53d1\u751f\uff1a<\/p>\n<ul>\n<li>\u5982\u679c n \u7b49\u4e8e 0\uff08\u5982\u7ebf\u7a0b t \u6ca1\u6709\u6301\u6709\u5bf9\u8c61 m \u7684\u9501\uff09\uff0c\u90a3\u4e48\u4f1a\u629b\u51fa IllegalMonitorStateException \u5f02\u5e38\u3002<\/li>\n<\/ul>\n<blockquote><p>\u6ce8\u610f\uff0c\u5982\u679c\u6ca1\u6709\u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501\uff0cwait \u65b9\u6cd5\u662f\u4f1a\u629b\u5f02\u5e38\u7684\uff0c\u800c\u4e14\u6ce8\u610f\u8fd9\u4e2a\u5f02\u5e38\u662fIllegalMonitorStateException\u5f02\u5e38\u3002\u8fd9\u662f\u91cd\u8981\u77e5\u8bc6\u70b9\uff0c\u8981\u8003\u3002<\/p><\/blockquote>\n<ul>\n<li>\u5982\u679c\u7ebf\u7a0b t \u8c03\u7528\u7684\u662f m.wait(millisecs) \u6216m.wait(millisecs, nanosecs)\uff0c\u5f62\u53c2millisecs \u4e0d\u80fd\u4e3a\u8d1f\u6570\uff0cnanosecs \u53d6\u503c\u5e94\u4e3a [0, 999999]\uff0c\u5426\u5219\u4f1a\u629b\u51faIllegalArgumentException \u5f02\u5e38\u3002<\/li>\n<li>\u5982\u679c\u7ebf\u7a0b t \u88ab\u4e2d\u65ad\uff0c\u6b64\u65f6\u4e2d\u65ad\u72b6\u6001\u4e3a true\uff0c\u5219 wait \u65b9\u6cd5\u5c06\u629b\u51fa InterruptedException \u5f02\u5e38\uff0c\u5e76\u5c06\u4e2d\u65ad\u72b6\u6001\u8bbe\u7f6e\u4e3a false\u3002<\/li>\n<\/ul>\n<blockquote><p>\u4e2d\u65ad\uff0c\u5982\u679c\u8bfb\u8005\u4e0d\u4e86\u89e3\u8fd9\u4e2a\u6982\u5ff5\uff0c\u53ef\u4ee5\u53c2\u8003\u6211\u5728 AQS(\u4e8c) \u4e2d\u7684\u4ecb\u7ecd\uff0c\u8fd9\u662f\u975e\u5e38\u91cd\u8981\u7684\u77e5\u8bc6\u3002<\/p><\/blockquote>\n<ul>\n<li>\u5426\u5219\uff0c\u4e0b\u9762\u7684\u64cd\u4f5c\u4f1a\u987a\u5e8f\u53d1\u751f\uff1a<\/li>\n<\/ul>\n<blockquote><p>\u6ce8\u610f\uff1a\u5230\u8fd9\u91cc\u7684\u65f6\u5019\uff0cwait \u53c2\u6570\u662f\u6b63\u5e38\u7684\uff0c\u540c\u65f6 t \u6ca1\u6709\u88ab\u4e2d\u65ad\uff0c\u5e76\u4e14\u7ebf\u7a0b t \u5df2\u7ecf\u62ff\u5230\u4e86 m \u7684\u76d1\u89c6\u5668\u9501\u3002<\/p><\/blockquote>\n<p><strong>1.\u7ebf\u7a0b t \u4f1a\u52a0\u5165\u5230\u5bf9\u8c61 m \u7684\u7b49\u5f85\u96c6\u5408\u4e2d\uff0c\u6267\u884c \u52a0\u9501\u7f16\u53f7 n \u5bf9\u5e94\u7684\u89e3\u9501\u64cd\u4f5c<\/strong><\/p>\n<p>\u8fd9\u91cc\u4e5f\u975e\u5e38\u5173\u952e\uff0c\u524d\u9762\u8bf4\u4e86\uff0cwait \u65b9\u6cd5\u7684\u8c03\u7528\u5fc5\u987b\u662f\u7ebf\u7a0b\u83b7\u53d6\u5230\u4e86\u5bf9\u8c61\u7684\u76d1\u89c6\u5668\u9501\uff0c\u800c\u5230\u8fd9\u91cc\u4f1a\u8fdb\u884c\u89e3\u9501\u64cd\u4f5c\u3002\u5207\u8bb0\u5207\u8bb0\u3002\u3002\u3002<\/p>\n<pre><code> public Object object = new Object();\n void thread1() {\n     synchronized (object) { \/\/ \u83b7\u53d6\u76d1\u89c6\u5668\u9501\n         try {\n             object.wait(); \/\/ \u8fd9\u91cc\u4f1a\u89e3\u9501\uff0c\u8fd9\u91cc\u4f1a\u89e3\u9501\uff0c\u8fd9\u91cc\u4f1a\u89e3\u9501\n             \/\/ \u987a\u4fbf\u63d0\u4e00\u4e0b\uff0c\u53ea\u662f\u89e3\u4e86object\u4e0a\u7684\u76d1\u89c6\u5668\u9501\uff0c\u5982\u679c\u8fd9\u4e2a\u7ebf\u7a0b\u8fd8\u6301\u6709\u5176\u4ed6\u5bf9\u8c61\u7684\u76d1\u89c6\u5668\u9501\uff0c\u8fd9\u4e2a\u65f6\u5019\u662f\u4e0d\u4f1a\u91ca\u653e\u7684\u3002\n         } catch (InterruptedException e) {\n             \/\/ do somethings\n         }\n     }\n }<\/code><\/pre>\n<p><strong>2.\u7ebf\u7a0b t \u4e0d\u4f1a\u6267\u884c\u4efb\u4f55\u8fdb\u4e00\u6b65\u7684\u6307\u4ee4\uff0c\u76f4\u5230\u5b83\u4ece m \u7684\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\uff08\u4e5f\u5c31\u662f\u7b49\u5f85\u5524\u9192\uff09\u3002\u5728\u53d1\u751f\u4ee5\u4e0b\u64cd\u4f5c\u7684\u65f6\u5019\uff0c\u7ebf\u7a0b t \u4f1a\u4ece m \u7684\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\uff0c\u7136\u540e\u5728\u4e4b\u540e\u7684\u67d0\u4e2a\u65f6\u95f4\u70b9\u6062\u590d\uff0c\u5e76\u7ee7\u7eed\u6267\u884c\u4e4b\u540e\u7684\u6307\u4ee4\u3002<\/strong><\/p>\n<blockquote><p>\u5e76\u4e0d\u662f\u8bf4\u7ebf\u7a0b\u79fb\u51fa\u7b49\u5f85\u961f\u5217\u5c31\u9a6c\u4e0a\u5f80\u4e0b\u6267\u884c\uff0c\u8fd9\u4e2a\u7ebf\u7a0b\u8fd8\u9700\u8981\u91cd\u65b0\u83b7\u53d6\u9501\u624d\u884c\uff0c\u8fd9\u91cc\u4e5f\u5f88\u5173\u952e\uff0c\u8bf7\u5f80\u540e\u770b17.2.4\u4e2d\u6211\u5199\u7684\u4e24\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\u3002<\/p><\/blockquote>\n<ul>\n<li>\u5728 m\u4e0a\u6267\u884c\u4e86 notify \u64cd\u4f5c\uff0c\u800c\u4e14\u7ebf\u7a0b t \u88ab\u9009\u4e2d\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u9664\u3002<\/li>\n<li>\u5728 m \u4e0a\u6267\u884c\u4e86 notifyAll \u64cd\u4f5c\uff0c\u90a3\u4e48\u7ebf\u7a0b t \u4f1a\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u9664\u3002<\/li>\n<li>\u7ebf\u7a0b t \u53d1\u751f\u4e86 interrupt \u64cd\u4f5c\u3002<\/li>\n<li>\u5982\u679c\u7ebf\u7a0b t \u662f\u8c03\u7528 wait(millisecs) \u6216\u8005 wait(millisecs, nanosecs) \u65b9\u6cd5\u8fdb\u5165\u7b49\u5f85\u96c6\u5408\u7684\uff0c\u90a3\u4e48\u8fc7\u4e86millisecs \u6beb\u79d2\u6216\u8005 (millisecs*1000000+nanosecs) \u7eb3\u79d2\u540e\uff0c\u7ebf\u7a0b t\u4e5f\u4f1a\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\u3002<\/li>\n<li>JVM \u7684\u201c\u5047\u5524\u9192\u201d\uff0c\u867d\u7136\u8fd9\u662f\u4e0d\u9f13\u52b1\u7684\uff0c\u4f46\u662f\u8fd9\u79cd\u64cd\u4f5c\u662f\u88ab\u5141\u8bb8\u7684\uff0c\u8fd9\u6837 JVM \u80fd\u5b9e\u73b0\u5c06\u7ebf\u7a0b\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\uff0c\u800c\u4e0d\u5fc5\u7b49\u5f85\u5177\u4f53\u7684\u79fb\u51fa\u6307\u4ee4\u3002<\/li>\n<\/ul>\n<p>\u6ce8\u610f\uff0c\u826f\u597d\u7684 Java \u7f16\u7801\u4e60\u60ef\u662f\uff0c\u53ea\u5728\u5faa\u73af\u4e2d\u4f7f\u7528 wait \u65b9\u6cd5\uff0c\u8fd9\u4e2a\u5faa\u73af\u7b49\u5f85\u67d0\u4e9b\u6761\u4ef6\u6765\u9000\u51fa\u5faa\u73af\u3002<\/p>\n<blockquote><p>\u4e2a\u4eba\u7406\u89e3wait\u65b9\u6cd5\u662f\u8fd9\u4e48\u7528\u7684\uff1a<\/p><\/blockquote>\n<pre><code> synchronized(m) {\n     while(!canExit) {\n       m.wait(10); \/\/ \u7b49\u5f8510ms; \u5f53\u7136\u4e2d\u65ad\u4e5f\u662f\u5e38\u7528\u7684\n       canExit = something();  \/\/ \u5224\u65ad\u662f\u5426\u53ef\u4ee5\u9000\u51fa\u5faa\u73af\n     }\n }\n \/\/ 2 \u4e2a\u77e5\u8bc6\u70b9\uff1a\n \/\/ 1. \u5fc5\u987b\u5148\u83b7\u53d6\u5230\u5bf9\u8c61\u4e0a\u7684\u76d1\u89c6\u5668\u9501\n \/\/ 2. wait \u6709\u53ef\u80fd\u88ab\u5047\u5524\u9192<\/code><\/pre>\n<p>\u6bcf\u4e2a\u7ebf\u7a0b\u5728\u4e00\u7cfb\u5217 <strong>\u53ef\u80fd\u5bfc\u81f4\u5b83\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\u7684\u4e8b\u4ef6<\/strong> \u4e2d\u5fc5\u987b\u51b3\u5b9a\u4e00\u4e2a\u987a\u5e8f\u3002\u8fd9\u4e2a\u987a\u5e8f\u4e0d\u5fc5\u8981\u548c\u5176\u4ed6\u987a\u5e8f\u4e00\u81f4\uff0c\u4f46\u662f\u7ebf\u7a0b\u5fc5\u987b\u8868\u73b0\u4e3a\u5b83\u662f\u6309\u7167\u90a3\u4e2a\u987a\u5e8f\u53d1\u751f\u7684\u3002<\/p>\n<p>\u4f8b\u5982\uff0c\u7ebf\u7a0b t \u73b0\u5728\u5728 m \u7684\u7b49\u5f85\u96c6\u5408\u4e2d\uff0c\u4e0d\u7ba1\u662f\u7ebf\u7a0b t \u4e2d\u65ad\u8fd8\u662f m \u7684 notify \u65b9\u6cd5\u88ab\u8c03\u7528\uff0c\u8fd9\u4e9b\u64cd\u4f5c\u4e8b\u4ef6\u80af\u5b9a\u5b58\u5728\u4e00\u4e2a\u987a\u5e8f\u3002\u5982\u679c\u7ebf\u7a0b t \u7684\u4e2d\u65ad\u5148\u53d1\u751f\uff0c\u90a3\u4e48 t \u4f1a\u56e0\u4e3a InterruptedException \u5f02\u5e38\u800c\u4ece wait \u65b9\u6cd5\u4e2d\u8fd4\u56de\uff0c\u540c\u65f6 m \u7684\u7b49\u5f85\u96c6\u5408\u4e2d\u7684\u5176\u4ed6\u7ebf\u7a0b\uff08\u5982\u679c\u6709\u7684\u8bdd\uff09\u4f1a\u6536\u5230\u8fd9\u4e2a\u901a\u77e5\u3002\u5982\u679c m \u7684 notify \u5148\u53d1\u751f\uff0c\u90a3\u4e48 t \u4f1a\u6b63\u5e38\u4ece wait \u65b9\u6cd5\u8fd4\u56de\uff0c\u4e14\u4e0d\u4f1a\u6539\u53d8\u4e2d\u65ad\u72b6\u6001\u3002<\/p>\n<p>\u6211\u4eec\u8003\u8651\u8fd9\u4e2a\u573a\u666f\uff1a<\/p>\n<p>\u7ebf\u7a0b 1 \u548c\u7ebf\u7a0b 2 \u6b64\u65f6\u90fd wait \u4e86\uff0c\u7ebf\u7a0b 3 \u8c03\u7528\u4e86 \uff1a<\/p>\n<pre><code>synchronized (object) {\n    thread1.interrupt(); \/\/1\n    object.notify();  \/\/2\n}<\/code><\/pre>\n<p>\u672c\u6765\u6211\u4ee5\u4e3a\u4e0a\u9762\u7684\u60c5\u51b5 \u7ebf\u7a0b1 \u4e00\u5b9a\u662f\u629b\u51fa InterruptedException\uff0c\u7ebf\u7a0b2 \u662f\u6b63\u5e38\u8fd4\u56de\u7684\u3002\u611f\u8c22\u8bc4\u8bba\u7559\u8a00\u7684 xupeng.zhang\uff0c\u6211\u7684\u8fd9\u4e2a\u60f3\u6cd5\u662f\u9519\u8bef\u7684\uff0c\u5b8c\u5168\u6709\u53ef\u80fd\u7ebf\u7a0b1\u6b63\u5e38\u8fd4\u56de(\u5373\u4f7f\u5176\u4e2d\u65ad\u72b6\u6001\u662ftrue)\uff0c\u7ebf\u7a0b2 \u4e00\u76f4 wait\u3002<\/p>\n<p><strong>3.\u7ebf\u7a0b t \u6267\u884c\u7f16\u53f7\u4e3a n \u7684\u52a0\u9501\u64cd\u4f5c<\/strong><\/p>\n<p>\u56de\u53bb\u770b 2  \u8bf4\u4e86\u4ec0\u4e48\uff0c\u7ebf\u7a0b\u521a\u521a\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\uff0c\u7136\u540e\u8fd9\u91cc\u9700\u8981\u91cd\u65b0\u83b7\u53d6\u76d1\u89c6\u5668\u9501\u624d\u80fd\u7ee7\u7eed\u5f80\u4e0b\u6267\u884c\u3002<\/p>\n<p><strong>4.\u5982\u679c\u7ebf\u7a0b t \u5728 2 \u7684\u65f6\u5019\u7531\u4e8e\u4e2d\u65ad\u800c\u4ece m \u7684\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\uff0c\u90a3\u4e48\u5b83\u7684\u4e2d\u65ad\u72b6\u6001\u4f1a\u91cd\u7f6e\u4e3a false\uff0c\u540c\u65f6 wait \u65b9\u6cd5\u4f1a\u629b\u51fa InterruptedException \u5f02\u5e38\u3002<\/strong><\/p>\n<p>\u8fd9\u4e00\u8282\u4e3b\u8981\u5728\u8bb2\u7ebf\u7a0b\u8fdb\u51fa\u7b49\u5f85\u96c6\u5408\u7684\u5404\u79cd\u60c5\u51b5\uff0c\u540c\u65f6\uff0c\u6700\u597d\u8981\u77e5\u9053\u4e2d\u65ad\u662f\u600e\u4e48\u7528\u7684\uff0c\u4e2d\u65ad\u7684\u72b6\u6001\u91cd\u7f6e\u53d1\u751f\u4e8e\u4ec0\u4e48\u65f6\u5019\u3002<\/p>\n<p>\u8fd9\u91cc\u7684 1\uff0c2\uff0c3\uff0c4 \u7684\u53d1\u751f\u987a\u5e8f\u975e\u5e38\u5173\u952e\uff0c\u5927\u5bb6\u53ef\u4ee5\u4ed4\u7ec6\u518d\u770b\u770b\u662f\u4e0d\u662f\u5b8c\u5168\u7406\u89e3\u4e86\uff0c\u4e4b\u540e\u7684\u51e0\u4e2a\u5c0f\u8282\u8fd8\u4f1a\u66f4\u5177\u4f53\u5730\u9610\u8ff0\u8fd9\u4e2a\uff0c\u53c2\u8003\u4ee3\u7801\u8bf7\u770b 17.2.4 \u5c0f\u8282\u6211\u5199\u7684\u7b80\u5355\u7684\u4f8b\u5b50\u3002<\/p>\n<h4>17.2.2 \u901a\u77e5\uff08Notification\uff09<\/h4>\n<p>\u901a\u77e5\u64cd\u4f5c\u53d1\u751f\u4e8e\u8c03\u7528 notify \u548c notifyAll \u65b9\u6cd5\u3002<\/p>\n<p>\u6211\u4eec\u5728\u7ebf\u7a0b t \u4e2d\u5bf9\u5bf9\u8c61 m \u8c03\u7528 m.notify() \u6216 m.notifyAll() \u65b9\u6cd5\uff0cn \u4ee3\u8868\u52a0\u9501\u7f16\u53f7\uff0c\u540c\u65f6\u5bf9\u5e94\u7684\u89e3\u9501\u64cd\u4f5c\u6ca1\u6709\u6267\u884c\uff0c\u5219\u4e0b\u9762\u7684\u5176\u4e2d\u4e4b\u4e00\u4f1a\u53d1\u751f\uff1a<\/p>\n<ul>\n<li>\u5982\u679c n \u7b49\u4e8e 0\uff0c\u629b\u51fa IllegalMonitorStateException \u5f02\u5e38\uff0c\u56e0\u4e3a\u7ebf\u7a0b t \u8fd8\u6ca1\u6709\u83b7\u53d6\u5230\u5bf9\u8c61 m \u4e0a\u7684\u9501\u3002<\/li>\n<\/ul>\n<p>\u8fd9\u4e00\u70b9\u5f88\u5173\u952e\uff0c\u53ea\u6709\u83b7\u53d6\u5230\u4e86\u5bf9\u8c61\u4e0a\u7684\u76d1\u89c6\u5668\u9501\u7684\u7ebf\u7a0b\u624d\u53ef\u4ee5\u6b63\u5e38\u8c03\u7528 notify\uff0c\u524d\u9762\u6211\u4eec\u4e5f\u8bf4\u8fc7\uff0c\u8c03\u7528 wait \u65b9\u6cd5\u7684\u65f6\u5019\u4e5f\u8981\u5148\u83b7\u53d6\u9501<\/p>\n<ul>\n<li>\u5982\u679c n \u5927\u4e8e 0\uff0c\u800c\u4e14\u8fd9\u662f\u4e00\u4e2a notify \u64cd\u4f5c\uff0c\u5982\u679c m \u7684\u7b49\u5f85\u96c6\u5408\u4e0d\u4e3a\u7a7a\uff0c\u90a3\u4e48\u7b49\u5f85\u96c6\u5408\u4e2d\u7684\u7ebf\u7a0b u \u88ab\u9009\u4e2d\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\u3002<\/li>\n<\/ul>\n<p>\u5bf9\u4e8e\u54ea\u4e2a\u7ebf\u7a0b\u4f1a\u88ab\u9009\u4e2d\u800c\u88ab\u79fb\u51fa\uff0c\u865a\u62df\u673a\u6ca1\u6709\u63d0\u4f9b\u4efb\u4f55\u4fdd\u8bc1\uff0c\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u5c06\u7ebf\u7a0b u \u79fb\u51fa\uff0c\u53ef\u4ee5\u8ba9\u7ebf\u7a0b u \u5f97\u4ee5\u6062\u590d\u3002\u6ce8\u610f\uff0c\u6062\u590d\u4e4b\u540e\u7684\u7ebf\u7a0b u \u5982\u679c\u5bf9 m \u8fdb\u884c\u52a0\u9501\u64cd\u4f5c\u5c06\u4e0d\u4f1a\u6210\u529f\uff0c\u76f4\u5230\u7ebf\u7a0b t \u5b8c\u5168\u91ca\u653e\u9501\u4e4b\u540e\u3002<\/p>\n<p>\u56e0\u4e3a\u7ebf\u7a0b t \u8fd9\u4e2a\u65f6\u5019\u8fd8\u6301\u6709 m \u7684\u9501\u3002\u8fd9\u4e2a\u77e5\u8bc6\u70b9\u5728 17.2.4 \u8282\u6211\u8fd8\u4f1a\u91cd\u70b9\u8bf4\u3002\u8fd9\u91cc\u8bb0\u4f4f\uff0c\u88ab notify \u7684\u7ebf\u7a0b\u5728\u5524\u9192\u540e\u662f\u9700\u8981\u91cd\u65b0\u83b7\u53d6\u76d1\u89c6\u5668\u9501\u7684\u3002<\/p>\n<ul>\n<li>\u5982\u679c n \u5927\u4e8e 0\uff0c\u800c\u4e14\u8fd9\u662f\u4e00\u4e2a notifyAll \u64cd\u4f5c\uff0c\u90a3\u4e48\u7b49\u5f85\u96c6\u5408\u4e2d\u7684\u6240\u6709\u7ebf\u7a0b\u90fd\u5c06\u4ece\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\uff0c\u7136\u540e\u6062\u590d\u3002<\/li>\n<\/ul>\n<p>\u6ce8\u610f\uff0c\u8fd9\u4e9b\u7ebf\u7a0b\u6062\u590d\u540e\uff0c\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u53ef\u4ee5\u9501\u4f4f\u76d1\u89c6\u5668\u3002<\/p>\n<p>\u672c\u5c0f\u8282\u7ed3\u675f\uff0c\u901a\u77e5\u64cd\u4f5c\u76f8\u5bf9\u6765\u8bf4\u8fd8\u662f\u5f88\u7b80\u5355\u7684\u5427\u3002<\/p>\n<h4>17.2.3 \u4e2d\u65ad\uff08Interruptions\uff09<\/h4>\n<p>\u4e2d\u65ad\u53d1\u751f\u4e8e Thread.interrupt \u65b9\u6cd5\u7684\u8c03\u7528\u3002<\/p>\n<p>\u4ee4\u7ebf\u7a0b t \u8c03\u7528\u7ebf\u7a0b u \u4e0a\u7684\u65b9\u6cd5 u.interrupt()\uff0c\u5176\u4e2d t \u548c u \u53ef\u4ee5\u662f\u540c\u4e00\u4e2a\u7ebf\u7a0b\uff0c\u8fd9\u4e2a\u64cd\u4f5c\u4f1a\u5c06 u \u7684\u4e2d\u65ad\u72b6\u6001\u8bbe\u7f6e\u4e3a true\u3002<\/p>\n<p>\u987a\u4fbf\u8bf4\u8bf4\u4e2d\u65ad\u72b6\u6001\u5427\uff0c\u521d\u5b66\u8005\u80af\u5b9a\u4ee5\u4e3a thread.interrupt() \u65b9\u6cd5\u662f\u7528\u6765\u6682\u505c\u7ebf\u7a0b\u7684\uff0c\u4e3b\u8981\u662f\u548c\u5b83\u5bf9\u5e94\u4e2d\u6587\u7ffb\u8bd1\u7684\u201c\u4e2d\u65ad\u201d\u6709\u5173\u3002\u4e2d\u65ad\u5728\u5e76\u53d1\u4e2d\u662f\u5e38\u7528\u7684\u624b\u6bb5\uff0c\u8bf7\u5927\u5bb6\u4e00\u5b9a\u597d\u597d\u638c\u63e1\u3002\u53ef\u4ee5\u5c06\u4e2d\u65ad\u7406\u89e3\u4e3a\u7ebf\u7a0b\u7684\u72b6\u6001\uff0c\u5b83\u7684\u7279\u6b8a\u4e4b\u5904\u5728\u4e8e\u8bbe\u7f6e\u4e86\u4e2d\u65ad\u72b6\u6001\u4e3a true \u540e\uff0c\u8fd9\u51e0\u4e2a\u65b9\u6cd5\u4f1a\u611f\u77e5\u5230\uff1a<\/p>\n<ul>\n<li>wait(), wait(long), wait(long, int), join(), join(long), join(long, int), sleep(long), sleep(long, int)\u8fd9\u4e9b\u65b9\u6cd5\u90fd\u6709\u4e00\u4e2a\u5171\u540c\u4e4b\u5904\uff0c\u65b9\u6cd5\u7b7e\u540d\u4e0a\u90fd\u6709throws InterruptedException\uff0c\u8fd9\u4e2a\u5c31\u662f\u7528\u6765\u54cd\u5e94\u4e2d\u65ad\u72b6\u6001\u4fee\u6539\u7684\u3002<\/li>\n<li>\u5982\u679c\u7ebf\u7a0b\u963b\u585e\u5728 InterruptibleChannel \u7c7b\u7684 IO \u64cd\u4f5c\u4e2d\uff0c\u90a3\u4e48\u8fd9\u4e2a channel \u4f1a\u88ab\u5173\u95ed\u3002<\/li>\n<li>\u5982\u679c\u7ebf\u7a0b\u963b\u585e\u5728\u4e00\u4e2a Selector \u4e2d\uff0c\u90a3\u4e48 select \u65b9\u6cd5\u4f1a\u7acb\u5373\u8fd4\u56de\u3002<\/li>\n<\/ul>\n<p>\u5982\u679c\u7ebf\u7a0b\u963b\u585e\u5728\u4ee5\u4e0a3\u79cd\u60c5\u51b5\u4e2d\uff0c\u90a3\u4e48\u5f53\u7ebf\u7a0b\u611f\u77e5\u5230\u4e2d\u65ad\u72b6\u6001\u540e\uff08\u6b64\u7ebf\u7a0b\u7684 interrupt() \u65b9\u6cd5\u88ab\u8c03\u7528\uff09\uff0c\u4f1a\u5c06\u4e2d\u65ad\u72b6\u6001\u91cd\u65b0\u8bbe\u7f6e\u4e3a false\uff0c\u7136\u540e\u6267\u884c\u76f8\u5e94\u7684\u64cd\u4f5c\uff08\u901a\u5e38\u5c31\u662f\u8df3\u5230 catch \u5f02\u5e38\u5904\uff09\u3002<\/p>\n<p>\u5982\u679c\u4e0d\u662f\u4ee5\u4e0a3\u79cd\u60c5\u51b5\uff0c\u90a3\u4e48\uff0c\u7ebf\u7a0b\u7684 interrupt() \u65b9\u6cd5\u88ab\u8c03\u7528\uff0c\u4f1a\u5c06\u7ebf\u7a0b\u7684\u4e2d\u65ad\u72b6\u6001\u8bbe\u7f6e\u4e3a true\u3002<\/p>\n<p>\u5f53\u7136\uff0c\u9664\u4e86\u8fd9\u51e0\u4e2a\u65b9\u6cd5\uff0c\u6211\u77e5\u9053\u7684\u662f LockSupport \u4e2d\u7684 park \u65b9\u6cd5\u4e5f\u80fd\u81ea\u52a8\u611f\u77e5\u5230\u7ebf\u7a0b\u88ab\u4e2d\u65ad\uff0c\u5f53\u7136\uff0c\u5b83\u4e0d\u4f1a\u91cd\u7f6e\u4e2d\u65ad\u72b6\u6001\u4e3a false\u3002\u6211\u4eec\u8bf4\u4e86\uff0c\u53ea\u6709\u4e0a\u9762\u7684\u51e0\u79cd\u60c5\u51b5\u4f1a\u5728\u611f\u77e5\u5230\u4e2d\u65ad\u540e\u5148\u91cd\u7f6e\u4e2d\u65ad\u72b6\u6001\u4e3a false\uff0c\u7136\u540e\u518d\u7ee7\u7eed\u6267\u884c\u3002<\/p>\n<p>\u53e6\u5916\uff0c\u5982\u679c\u6709\u4e00\u4e2a\u5bf9\u8c61 m\uff0c\u800c\u4e14\u7ebf\u7a0b u \u6b64\u65f6\u5728 m \u7684\u7b49\u5f85\u96c6\u5408\u4e2d\uff0c\u90a3\u4e48 u \u5c06\u4f1a\u4ece m \u7684\u7b49\u5f85\u96c6\u5408\u4e2d\u79fb\u51fa\u3002\u8fd9\u4f1a\u8ba9 u \u4ece wait \u64cd\u4f5c\u4e2d\u6062\u590d\u8fc7\u6765\uff0cu \u6b64\u65f6\u9700\u8981\u83b7\u53d6 m \u7684\u76d1\u89c6\u5668\u9501\uff0c\u83b7\u53d6\u5b8c\u9501\u4ee5\u540e\uff0c\u53d1\u73b0\u7ebf\u7a0b u \u5904\u4e8e\u4e2d\u65ad\u72b6\u6001\uff0c\u6b64\u65f6\u4f1a\u629b\u51fa InterruptedException \u5f02\u5e38\u3002<\/p>\n<p>\u8fd9\u91cc\u7684\u6d41\u7a0b\uff1at \u8bbe\u7f6e u \u7684\u4e2d\u65ad\u72b6\u6001 =&gt; u \u7ebf\u7a0b\u6062\u590d =&gt; u \u83b7\u53d6 m \u7684\u76d1\u89c6\u5668\u9501 =&gt; \u83b7\u53d6\u9501\u4ee5\u540e\uff0c\u629b\u51fa InterruptedException \u5f02\u5e38\u3002<\/p>\n<p>\u8fd9\u4e2a\u6d41\u7a0b\u5728\u524d\u9762 wait \u7684\u5c0f\u8282\u5df2\u7ecf\u8bb2\u8fc7\u4e86\uff0c\u8fd9\u4e5f\u662f\u5f88\u591a\u4eba\u90fd\u4e0d\u4e86\u89e3\u7684\u77e5\u8bc6\u70b9\u3002\u5982\u679c\u8fd8\u4e0d\u61c2\uff0c\u53ef\u4ee5\u770b\u4e0b\u4e00\u5c0f\u8282\u7684\u7ed3\u675f\uff0c\u6211\u7684\u4e24\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\u3002<\/p>\n<p>\u4e00\u4e2a\u5c0f\u7ec6\u8282\uff1au \u88ab\u4e2d\u65ad\uff0cwait \u65b9\u6cd5\u8fd4\u56de\uff0c\u5e76\u4e0d\u4f1a\u7acb\u5373\u629b\u51fa InterruptedException \u5f02\u5e38\uff0c\u800c\u662f\u5728\u91cd\u65b0\u83b7\u53d6\u76d1\u89c6\u5668\u9501\u4e4b\u540e\u624d\u4f1a\u629b\u51fa\u5f02\u5e38\u3002<\/p>\n<p>\u5b9e\u4f8b\u65b9\u6cd5 thread.isInterrupted() \u53ef\u4ee5\u77e5\u9053\u7ebf\u7a0b\u7684\u4e2d\u65ad\u72b6\u6001\u3002<\/p>\n<p>\u8c03\u7528\u9759\u6001\u65b9\u6cd5 Thread.interrupted() \u53ef\u4ee5\u8fd4\u56de\u5f53\u524d\u7ebf\u7a0b\u7684\u4e2d\u65ad\u72b6\u6001\uff0c\u540c\u65f6\u5c06\u4e2d\u65ad\u72b6\u6001\u8bbe\u7f6e\u4e3afalse\u3002<\/p>\n<blockquote><p>\u6240\u4ee5\u8bf4\uff0c\u5982\u679c\u662f\u8fd9\u4e2a\u65b9\u6cd5\u8c03\u7528\u4e24\u6b21\uff0c\u90a3\u4e48\u7b2c\u4e8c\u6b21\u4e00\u5b9a\u4f1a\u8fd4\u56de false\uff0c\u56e0\u4e3a\u7b2c\u4e00\u6b21\u4f1a\u91cd\u7f6e\u72b6\u6001\u3002\u5f53\u7136\u4e86\uff0c\u524d\u63d0\u662f\u4e24\u6b21\u8c03\u7528\u7684\u4e2d\u95f4\u6ca1\u6709\u53d1\u751f\u8bbe\u7f6e\u7ebf\u7a0b\u4e2d\u65ad\u72b6\u6001\u7684\u5176\u4ed6\u8bed\u53e5\u3002<\/p><\/blockquote>\n<h4>17.2.4 \u7b49\u5f85\u3001\u901a\u77e5\u548c\u4e2d\u65ad\u7684\u4ea4\u4e92\uff08Interactions of Waits, Notification, and Interruption\uff09<\/h4>\n<p>\u4ee5\u4e0a\u7684\u4e00\u7cfb\u5217\u89c4\u8303\u80fd\u8ba9\u6211\u4eec\u786e\u5b9a \u5728\u7b49\u5f85\u3001\u901a\u77e5\u3001\u4e2d\u65ad\u7684\u4ea4\u4e92\u4e2d \u6709\u5173\u7684\u51e0\u4e2a\u5c5e\u6027\u3002<\/p>\n<p>\u5982\u679c\u4e00\u4e2a\u7ebf\u7a0b\u5728\u7b49\u5f85\u671f\u95f4\uff0c\u540c\u65f6\u53d1\u751f\u4e86\u901a\u77e5\u548c\u4e2d\u65ad\uff0c\u5b83\u5c06\u53d1\u751f\uff1a<\/p>\n<ul>\n<li>\u4ece wait \u65b9\u6cd5\u4e2d\u6b63\u5e38\u8fd4\u56de\uff0c\u540c\u65f6\u4e0d\u6539\u53d8\u4e2d\u65ad\u72b6\u6001\uff08\u4e5f\u5c31\u662f\u8bf4\uff0c\u8c03\u7528 Thread.interrupted \u65b9\u6cd5\u5c06\u4f1a\u8fd4\u56de true\uff09<\/li>\n<li>\u7531\u4e8e\u629b\u51fa\u4e86 InterruptedException \u5f02\u5e38\u800c\u4ece wait \u65b9\u6cd5\u4e2d\u8fd4\u56de\uff0c\u4e2d\u65ad\u72b6\u6001\u8bbe\u7f6e\u4e3a false<\/li>\n<\/ul>\n<p>\u7ebf\u7a0b\u53ef\u80fd\u6ca1\u6709\u91cd\u7f6e\u5b83\u7684\u4e2d\u65ad\u72b6\u6001\uff0c\u540c\u65f6\u4ece wait \u65b9\u6cd5\u4e2d\u6b63\u5e38\u8fd4\u56de\uff0c\u5373\u7b2c\u4e00\u79cd\u60c5\u51b5\u3002<\/p>\n<blockquote><p>\u4e5f\u5c31\u662f\u8bf4\uff0c\u7ebf\u7a0b\u662f\u4ece notify \u88ab\u5524\u9192\u7684\uff0c\u7531\u4e8e\u53d1\u751f\u4e86\u4e2d\u65ad\uff0c\u6240\u4ee5\u4e2d\u65ad\u72b6\u6001\u4e3a true<\/p><\/blockquote>\n<p>\u540c\u6837\u7684\uff0c\u901a\u77e5\u4e5f\u4e0d\u80fd\u7531\u4e8e\u4e2d\u65ad\u800c\u4e22\u5931\u3002<\/p>\n<blockquote><p>\u8fd9\u4e2a\u8981\u8bf4\u7684\u662f\uff0c\u7ebf\u7a0b\u5176\u5b9e\u662f\u4ece\u4e2d\u65ad\u5524\u9192\u7684\uff0c\u90a3\u4e48\u7ebf\u7a0b\u9192\u8fc7\u6765\uff0c\u540c\u65f6\u4e2d\u65ad\u72b6\u6001\u4f1a\u88ab\u91cd\u7f6e\u4e3a false\u3002<\/p><\/blockquote>\n<p>\u5047\u8bbe m \u7684\u7b49\u5f85\u96c6\u5408\u4e3a \u7ebf\u7a0b\u96c6\u5408 s\uff0c\u5e76\u4e14\u5728\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u4e2d\u8c03\u7528\u4e86 m.notify(), \u90a3\u4e48\u5c06\u53d1\u751f\uff1a<\/p>\n<ul>\n<li>\u81f3\u5c11\u6709\u96c6\u5408 s \u4e2d\u7684\u4e00\u4e2a\u7ebf\u7a0b\u6b63\u5e38\u4ece wait \u65b9\u6cd5\u8fd4\u56de\uff0c\u6216\u8005<\/li>\n<li>\u96c6\u5408 s \u4e2d\u7684\u6240\u6709\u7ebf\u7a0b\u7531\u629b\u51fa InterruptedException \u5f02\u5e38\u800c\u8fd4\u56de\u3002<\/li>\n<\/ul>\n<blockquote><p>\u8003\u8651\u662f\u5426\u6709\u8fd9\u4e2a\u573a\u666f\uff1ax \u88ab\u8bbe\u7f6e\u4e86\u4e2d\u65ad\u72b6\u6001\uff0cnotify \u9009\u4e2d\u4e86\u96c6\u5408\u4e2d\u7684\u7ebf\u7a0b x\uff0c\u90a3\u4e48\u8fd9\u6b21 notify \u5c06\u5524\u9192\u7ebf\u7a0b x\uff0c\u5176\u4ed6\u7ebf\u7a0b\uff08\u6211\u4eec\u5047\u8bbe\u8fd8\u6709\u5176\u4ed6\u7ebf\u7a0b\u5728\u7b49\u5f85\uff09\u4e0d\u4f1a\u6709\u53d8\u5316\u3002<\/p><\/blockquote>\n<p>\u7b54\u6848\uff1a\u5b58\u5728\u8fd9\u79cd\u573a\u666f\u3002\u56e0\u4e3a\u8fd9\u79cd\u573a\u666f\u662f\u6ee1\u8db3\u4e0a\u8ff0\u6761\u4ef6\u7684\uff0c\u800c\u4e14\u6b64\u65f6 x \u7684\u4e2d\u65ad\u72b6\u6001\u662f true\u3002<\/p>\n<p>\u6ce8\u610f\uff0c\u5982\u679c\u4e00\u4e2a\u7ebf\u7a0b\u540c\u65f6\u88ab\u4e2d\u65ad\u548c\u901a\u77e5\u5524\u9192\uff0c\u540c\u65f6\u8fd9\u4e2a\u7ebf\u7a0b\u901a\u8fc7\u629b\u51fa InterruptedException \u5f02\u5e38\u4ece wait \u4e2d\u8fd4\u56de\uff0c\u90a3\u4e48\u7b49\u5f85\u96c6\u5408\u4e2d\u7684\u67d0\u4e2a\u5176\u4ed6\u7ebf\u7a0b\u4e00\u5b9a\u4f1a\u88ab\u901a\u77e5\u3002<\/p>\n<p>\u4e0b\u9762\u6211\u4eec\u901a\u8fc7 3 \u4e2a\u4f8b\u5b50\u7b80\u5355\u5206\u6790\u4e0b wait\u3001notify\u3001\u4e2d\u65ad \u5b83\u4eec\u7684\u7ec4\u5408\u4f7f\u7528\u3002<\/p>\n<p>\u7b2c\u4e00\u4e2a\u4f8b\u5b50\u5c55\u793a\u4e86 wait \u548c notify \u64cd\u4f5c\u8fc7\u7a0b\u4e2d\u7684\u76d1\u89c6\u5668\u9501\u7684 \u6301\u6709\u3001\u91ca\u653e \u7684\u95ee\u9898\u3002\u8003\u8651\u4ee5\u4e0b\u64cd\u4f5c\uff1a<\/p>\n<pre><code>public class WaitNotify {\n\n    public static void main(String[] args) {\n\n        Object object = new Object();\n\n        new Thread(new Runnable() {\n            @Override\n            public void run() {\n\n                synchronized (object) {\n                    System.out.println(&quot;\u7ebf\u7a0b1 \u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501&quot;);\n                    try {\n                        object.wait();\n                        System.out.println(&quot;\u7ebf\u7a0b1 \u6062\u590d\u5566\u3002\u6211\u4e3a\u4ec0\u4e48\u8fd9\u4e48\u4e45\u624d\u6062\u590d\uff0c\u56e0\u4e3anotify\u65b9\u6cd5\u867d\u7136\u65e9\u5c31\u53d1\u751f\u4e86\uff0c\u53ef\u662f\u6211\u8fd8\u8981\u83b7\u53d6\u9501\u624d\u80fd\u7ee7\u7eed\u6267\u884c\u3002&quot;);\n                    } catch (InterruptedException e) {\n                        System.out.println(&quot;\u7ebf\u7a0b1 wait\u65b9\u6cd5\u629b\u51fa\u4e86InterruptedException\u5f02\u5e38&quot;);\n                    }\n                }\n            }\n        }, &quot;\u7ebf\u7a0b1&quot;).start();\n\n        new Thread(new Runnable() {\n            @Override\n            public void run() {\n                synchronized (object) {\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u62ff\u5230\u4e86\u76d1\u89c6\u5668\u9501\u3002\u4e3a\u4ec0\u4e48\u5462\uff0c\u56e0\u4e3a\u7ebf\u7a0b1 \u5728 wait \u65b9\u6cd5\u7684\u65f6\u5019\u4f1a\u81ea\u52a8\u91ca\u653e\u9501&quot;);\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u6267\u884c notify \u64cd\u4f5c&quot;);\n                    object.notify();\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u6267\u884c\u5b8c\u4e86 notify\uff0c\u5148\u4f11\u606f3\u79d2\u518d\u8bf4\u3002&quot;);\n                    try {\n                        Thread.sleep(3000);\n                        System.out.println(&quot;\u7ebf\u7a0b2 \u4f11\u606f\u5b8c\u5566\u3002\u6ce8\u610f\u4e86\uff0c\u8c03sleep\u65b9\u6cd5\u548cwait\u65b9\u6cd5\u4e0d\u4e00\u6837\uff0c\u4e0d\u4f1a\u91ca\u653e\u76d1\u89c6\u5668\u9501&quot;);\n                    } catch (InterruptedException e) {\n\n                    }\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u4f11\u606f\u591f\u4e86\uff0c\u7ed3\u675f\u64cd\u4f5c&quot;);\n                }\n            }\n        }, &quot;\u7ebf\u7a0b2&quot;).start();\n    }\n}\n\noutput\uff1a\n\u7ebf\u7a0b1 \u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501\n\u7ebf\u7a0b2 \u62ff\u5230\u4e86\u76d1\u89c6\u5668\u9501\u3002\u4e3a\u4ec0\u4e48\u5462\uff0c\u56e0\u4e3a\u7ebf\u7a0b1 \u5728 wait \u65b9\u6cd5\u7684\u65f6\u5019\u4f1a\u81ea\u52a8\u91ca\u653e\u9501\n\u7ebf\u7a0b2 \u6267\u884c notify \u64cd\u4f5c\n\u7ebf\u7a0b2 \u6267\u884c\u5b8c\u4e86 notify\uff0c\u5148\u4f11\u606f3\u79d2\u518d\u8bf4\u3002\n\u7ebf\u7a0b2 \u4f11\u606f\u5b8c\u5566\u3002\u6ce8\u610f\u4e86\uff0c\u8c03sleep\u65b9\u6cd5\u548cwait\u65b9\u6cd5\u4e0d\u4e00\u6837\uff0c\u4e0d\u4f1a\u91ca\u653e\u76d1\u89c6\u5668\u9501\n\u7ebf\u7a0b2 \u4f11\u606f\u591f\u4e86\uff0c\u7ed3\u675f\u64cd\u4f5c\n\u7ebf\u7a0b1 \u6062\u590d\u5566\u3002\u6211\u4e3a\u4ec0\u4e48\u8fd9\u4e48\u4e45\u624d\u6062\u590d\uff0c\u56e0\u4e3anotify\u65b9\u6cd5\u867d\u7136\u65e9\u5c31\u53d1\u751f\u4e86\uff0c\u53ef\u662f\u6211\u8fd8\u8981\u83b7\u53d6\u9501\u624d\u80fd\u7ee7\u7eed\u6267\u884c\u3002<\/code><\/pre>\n<p>\u4e0a\u9762\u7684\u4f8b\u5b50\u5c55\u793a\u4e86\uff0cwait \u65b9\u6cd5\u8fd4\u56de\u540e\uff0c\u9700\u8981\u91cd\u65b0\u83b7\u53d6\u76d1\u89c6\u5668\u9501\uff0c\u624d\u53ef\u4ee5\u7ee7\u7eed\u5f80\u4e0b\u6267\u884c\u3002<\/p>\n<p>\u540c\u7406\uff0c\u6211\u4eec\u7a0d\u5fae\u4fee\u6539\u4e0b\u4ee5\u4e0a\u7684\u7a0b\u5e8f\uff0c\u770b\u4e0b\u4e2d\u65ad\u548c wait \u4e4b\u95f4\u7684\u4ea4\u4e92\uff1a<\/p>\n<pre><code>public class WaitNotify {\n\n    public static void main(String[] args) {\n\n        Object object = new Object();\n\n        Thread thread1 = new Thread(new Runnable() {\n            @Override\n            public void run() {\n\n                synchronized (object) {\n                    System.out.println(&quot;\u7ebf\u7a0b1 \u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501&quot;);\n                    try {\n                        object.wait();\n                        System.out.println(&quot;\u7ebf\u7a0b1 \u6062\u590d\u5566\u3002\u6211\u4e3a\u4ec0\u4e48\u8fd9\u4e48\u4e45\u624d\u6062\u590d\uff0c\u56e0\u4e3anotify\u65b9\u6cd5\u867d\u7136\u65e9\u5c31\u53d1\u751f\u4e86\uff0c\u53ef\u662f\u6211\u8fd8\u8981\u83b7\u53d6\u9501\u624d\u80fd\u7ee7\u7eed\u6267\u884c\u3002&quot;);\n                    } catch (InterruptedException e) {\n                        System.out.println(&quot;\u7ebf\u7a0b1 wait\u65b9\u6cd5\u629b\u51fa\u4e86InterruptedException\u5f02\u5e38\uff0c\u5373\u4f7f\u662f\u5f02\u5e38\uff0c\u6211\u4e5f\u662f\u8981\u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501\u4e86\u624d\u4f1a\u629b\u51fa&quot;);\n                    }\n                }\n            }\n        }, &quot;\u7ebf\u7a0b1&quot;);\n        thread1.start();\n\n        new Thread(new Runnable() {\n            @Override\n            public void run() {\n                synchronized (object) {\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u62ff\u5230\u4e86\u76d1\u89c6\u5668\u9501\u3002\u4e3a\u4ec0\u4e48\u5462\uff0c\u56e0\u4e3a\u7ebf\u7a0b1 \u5728 wait \u65b9\u6cd5\u7684\u65f6\u5019\u4f1a\u81ea\u52a8\u91ca\u653e\u9501&quot;);\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u8bbe\u7f6e\u7ebf\u7a0b1 \u4e2d\u65ad&quot;);\n                    thread1.interrupt();\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u6267\u884c\u5b8c\u4e86 \u4e2d\u65ad\uff0c\u5148\u4f11\u606f3\u79d2\u518d\u8bf4\u3002&quot;);\n                    try {\n                        Thread.sleep(3000);\n                        System.out.println(&quot;\u7ebf\u7a0b2 \u4f11\u606f\u5b8c\u5566\u3002\u6ce8\u610f\u4e86\uff0c\u8c03sleep\u65b9\u6cd5\u548cwait\u65b9\u6cd5\u4e0d\u4e00\u6837\uff0c\u4e0d\u4f1a\u91ca\u653e\u76d1\u89c6\u5668\u9501&quot;);\n                    } catch (InterruptedException e) {\n\n                    }\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u4f11\u606f\u591f\u4e86\uff0c\u7ed3\u675f\u64cd\u4f5c&quot;);\n                }\n            }\n        }, &quot;\u7ebf\u7a0b2&quot;).start();\n    }\n}\noutput:\n\u7ebf\u7a0b1 \u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501\n\u7ebf\u7a0b2 \u62ff\u5230\u4e86\u76d1\u89c6\u5668\u9501\u3002\u4e3a\u4ec0\u4e48\u5462\uff0c\u56e0\u4e3a\u7ebf\u7a0b1 \u5728 wait \u65b9\u6cd5\u7684\u65f6\u5019\u4f1a\u81ea\u52a8\u91ca\u653e\u9501\n\u7ebf\u7a0b2 \u8bbe\u7f6e\u7ebf\u7a0b1 \u4e2d\u65ad\n\u7ebf\u7a0b2 \u6267\u884c\u5b8c\u4e86 \u4e2d\u65ad\uff0c\u5148\u4f11\u606f3\u79d2\u518d\u8bf4\u3002\n\u7ebf\u7a0b2 \u4f11\u606f\u5b8c\u5566\u3002\u6ce8\u610f\u4e86\uff0c\u8c03sleep\u65b9\u6cd5\u548cwait\u65b9\u6cd5\u4e0d\u4e00\u6837\uff0c\u4e0d\u4f1a\u91ca\u653e\u76d1\u89c6\u5668\u9501\n\u7ebf\u7a0b2 \u4f11\u606f\u591f\u4e86\uff0c\u7ed3\u675f\u64cd\u4f5c\n\u7ebf\u7a0b1 wait\u65b9\u6cd5\u629b\u51fa\u4e86InterruptedException\u5f02\u5e38\uff0c\u5373\u4f7f\u662f\u5f02\u5e38\uff0c\u6211\u4e5f\u662f\u8981\u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501\u4e86\u624d\u4f1a\u629b\u51fa<\/code><\/pre>\n<p>\u4e0a\u9762\u7684\u8fd9\u4e2a\u4f8b\u5b50\u4e5f\u5f88\u6e05\u695a\uff0c\u5982\u679c\u7ebf\u7a0b\u8c03\u7528 wait \u65b9\u6cd5\uff0c\u5f53\u6b64\u7ebf\u7a0b\u88ab\u4e2d\u65ad\u7684\u65f6\u5019\uff0cwait \u65b9\u6cd5\u4f1a\u8fd4\u56de\uff0c\u7136\u540e\u91cd\u65b0\u83b7\u53d6\u76d1\u89c6\u5668\u9501\uff0c\u7136\u540e\u629b\u51faInterruptedException \u5f02\u5e38\u3002<\/p>\n<p>\u6211\u4eec\u518d\u6765\u8003\u8651\u4e0b\uff0c\u4e4b\u524d\u8bf4\u7684 notify \u548c\u4e2d\u65ad\uff1a<\/p>\n<pre><code>package com.javadoop.learning;\n\n\/**\n * Created by hongjie on 2017\/7\/7.\n *\/\npublic class WaitNotify {\n\n    volatile int a = 0;\n\n    public static void main(String[] args) {\n\n        Object object = new Object();\n\n        WaitNotify waitNotify = new WaitNotify();\n\n        Thread thread1 = new Thread(new Runnable() {\n            @Override\n            public void run() {\n\n                synchronized (object) {\n                    System.out.println(&quot;\u7ebf\u7a0b1 \u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501&quot;);\n                    try {\n                        object.wait();\n                        System.out.println(&quot;\u7ebf\u7a0b1 \u6b63\u5e38\u6062\u590d\u5566\u3002&quot;);\n                    } catch (InterruptedException e) {\n                        System.out.println(&quot;\u7ebf\u7a0b1 wait\u65b9\u6cd5\u629b\u51fa\u4e86InterruptedException\u5f02\u5e38&quot;);\n                    }\n                }\n            }\n        }, &quot;\u7ebf\u7a0b1&quot;);\n        thread1.start();\n\n        Thread thread2 = new Thread(new Runnable() {\n            @Override\n            public void run() {\n\n                synchronized (object) {\n                    System.out.println(&quot;\u7ebf\u7a0b2 \u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501&quot;);\n                    try {\n                        object.wait();\n                        System.out.println(&quot;\u7ebf\u7a0b2 \u6b63\u5e38\u6062\u590d\u5566\u3002&quot;);\n                    } catch (InterruptedException e) {\n                        System.out.println(&quot;\u7ebf\u7a0b2 wait\u65b9\u6cd5\u629b\u51fa\u4e86InterruptedException\u5f02\u5e38&quot;);\n                    }\n                }\n            }\n        }, &quot;\u7ebf\u7a0b2&quot;);\n        thread2.start();\n\n         \/\/ \u8fd9\u91cc\u8ba9 thread1 \u548c thread2 \u5148\u8d77\u6765\uff0c\u7136\u540e\u518d\u8d77\u540e\u9762\u7684 thread3\n        try {\n            Thread.sleep(1000);\n        } catch (InterruptedException e) {\n        }\n\n        new Thread(new Runnable() {\n            @Override\n            public void run() {\n                synchronized (object) {\n                    System.out.println(&quot;\u7ebf\u7a0b3 \u62ff\u5230\u4e86\u76d1\u89c6\u5668\u9501\u3002&quot;);\n                    System.out.println(&quot;\u7ebf\u7a0b3 \u8bbe\u7f6e\u7ebf\u7a0b1\u4e2d\u65ad&quot;);\n                    thread1.interrupt(); \/\/ 1\n                    waitNotify.a = 1; \/\/ \u8fd9\u884c\u662f\u4e3a\u4e86\u7981\u6b62\u4e0a\u4e0b\u7684\u4e24\u884c\u4e2d\u65ad\u548cnotify\u4ee3\u7801\u91cd\u6392\u5e8f\n                    System.out.println(&quot;\u7ebf\u7a0b3 \u8c03\u7528notify&quot;);\n                    object.notify(); \/\/2\n                    System.out.println(&quot;\u7ebf\u7a0b3 \u8c03\u7528\u5b8cnotify\u540e\uff0c\u4f11\u606f\u4e00\u4f1a&quot;);\n                    try {\n                        Thread.sleep(3000);\n                    } catch (InterruptedException e) {\n                    }\n                    System.out.println(&quot;\u7ebf\u7a0b3 \u4f11\u606f\u591f\u4e86\uff0c\u7ed3\u675f\u540c\u6b65\u4ee3\u7801\u5757&quot;);\n                }\n            }\n        }, &quot;\u7ebf\u7a0b3&quot;).start();\n    }\n}\n\n\/\/ \u6700\u5e38\u89c1\u7684output:\n\u7ebf\u7a0b1 \u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501\n\u7ebf\u7a0b2 \u83b7\u53d6\u5230\u76d1\u89c6\u5668\u9501\n\u7ebf\u7a0b3 \u62ff\u5230\u4e86\u76d1\u89c6\u5668\u9501\u3002\n\u7ebf\u7a0b3 \u8bbe\u7f6e\u7ebf\u7a0b1\u4e2d\u65ad\n\u7ebf\u7a0b3 \u8c03\u7528notify\n\u7ebf\u7a0b3 \u8c03\u7528\u5b8cnotify\u540e\uff0c\u4f11\u606f\u4e00\u4f1a\n\u7ebf\u7a0b3 \u4f11\u606f\u591f\u4e86\uff0c\u7ed3\u675f\u540c\u6b65\u4ee3\u7801\u5757\n\u7ebf\u7a0b2 \u6b63\u5e38\u6062\u590d\u5566\u3002\n\u7ebf\u7a0b1 wait\u65b9\u6cd5\u629b\u51fa\u4e86InterruptedException\u5f02\u5e38<\/code><\/pre>\n<p>\u4e0a\u8ff0\u8f93\u51fa\u4e0d\u662f\u7edd\u5bf9\u7684\uff0c\u6709\u53ef\u80fd\u53d1\u751f \u7ebf\u7a0b1 \u662f\u6b63\u5e38\u6062\u590d\u7684\uff0c\u867d\u7136\u53d1\u751f\u4e86\u4e2d\u65ad\uff0c\u5b83\u7684\u4e2d\u65ad\u72b6\u6001\u4e5f\u786e\u5b9e\u662f true\uff0c\u4f46\u662f\u5b83\u6ca1\u6709\u629b\u51fa InterruptedException\uff0c\u800c\u662f\u6b63\u5e38\u8fd4\u56de\u3002\u6b64\u65f6\uff0cthread2 \u5c06\u5f97\u4e0d\u5230\u5524\u9192\uff0c\u4e00\u76f4 wait\u3002<\/p>\n<h3>17.3. \u4f11\u7720\u548c\u793c\u8ba9\uff08Sleep and Yield\uff09<\/h3>\n<p>Thread.sleep(millisecs) \u4f7f\u5f53\u524d\u6b63\u5728\u6267\u884c\u7684\u7ebf\u7a0b\u4f11\u7720\u6307\u5b9a\u7684\u4e00\u6bb5\u65f6\u95f4\uff08\u6682\u65f6\u505c\u6b62\u6267\u884c\u4efb\u4f55\u6307\u4ee4\uff09\uff0c\u65f6\u95f4\u53d6\u51b3\u4e8e\u53c2\u6570\u503c\uff0c\u7cbe\u5ea6\u53d7\u5236\u4e8e\u7cfb\u7edf\u7684\u5b9a\u65f6\u5668\u3002<strong>\u4f11\u7720\u671f\u95f4\uff0c\u7ebf\u7a0b\u4e0d\u4f1a\u91ca\u653e\u4efb\u4f55\u7684\u76d1\u89c6\u5668\u9501<\/strong>\u3002\u7ebf\u7a0b\u7684\u6062\u590d\u53d6\u51b3\u4e8e\u5b9a\u65f6\u5668\u548c\u5904\u7406\u5668\u7684\u53ef\u7528\u6027\uff0c\u5373\u6709\u53ef\u7528\u7684\u5904\u7406\u5668\u6765\u5524\u9192\u7ebf\u7a0b\u3002<\/p>\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0cThread.sleep \u548c Thread.yield \u90fd\u4e0d\u5177\u6709\u540c\u6b65\u7684\u8bed\u4e49\u3002\u5728 Thread.sleep \u548c Thread.yield \u65b9\u6cd5\u8c03\u7528\u4e4b\u524d\uff0c\u4e0d\u8981\u6c42\u865a\u62df\u673a\u5c06\u5bc4\u5b58\u5668\u4e2d\u7684\u7f13\u5b58\u5237\u51fa\u5230\u5171\u4eab\u5185\u5b58\u4e2d\uff0c\u540c\u65f6\u4e5f\u4e0d\u8981\u6c42\u865a\u62df\u673a\u5728\u8fd9\u4e24\u4e2a\u65b9\u6cd5\u8c03\u7528\u4e4b\u540e\uff0c\u91cd\u65b0\u4ece\u5171\u4eab\u5185\u5b58\u4e2d\u8bfb\u53d6\u6570\u636e\u5230\u7f13\u5b58\u3002<\/p>\n<p>\u4f8b\u5982\uff0c\u6211\u4eec\u6709\u5982\u4e0b\u4ee3\u7801\u5757\uff0cthis.done \u5b9a\u4e49\u4e3a\u4e00\u4e2a non-volatile \u7684\u5c5e\u6027\uff0c\u521d\u59cb\u503c\u4e3a false\u3002<\/p>\n<pre><code>while (!this.done)\n    Thread.sleep(1000);<\/code><\/pre>\n<p>\u7f16\u8bd1\u5668\u53ef\u4ee5\u53ea\u8bfb\u53d6\u4e00\u6b21 this.done \u5230\u7f13\u5b58\u4e2d\uff0c\u7136\u540e\u4e00\u76f4\u4f7f\u7528\u7f13\u5b58\u4e2d\u7684\u503c\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u8fd9\u4e2a\u5faa\u73af\u53ef\u80fd\u6c38\u8fdc\u4e0d\u4f1a\u7ed3\u675f\uff0c\u5373\u4f7f\u662f\u6709\u5176\u4ed6\u7ebf\u7a0b\u5c06 this.done \u7684\u503c\u4fee\u6539\u4e3a true\u3002<\/p>\n<p>yield \u662f\u544a\u8bc9\u64cd\u4f5c\u7cfb\u7edf\u7684\u8c03\u5ea6\u5668\uff1a\u6211\u7684cpu\u53ef\u4ee5\u5148\u8ba9\u7ed9\u5176\u4ed6\u7ebf\u7a0b\u3002\u6ce8\u610f\uff0c\u8c03\u5ea6\u5668\u53ef\u4ee5\u4e0d\u7406\u4f1a\u8fd9\u4e2a\u4fe1\u606f\u3002<\/p>\n<p>\u8fd9\u4e2a\u65b9\u6cd5\u592a\u9e21\u808b\uff0c\u51e0\u4e4e\u6ca1\u7528\u3002<\/p>\n<h3>17.4 \u5185\u5b58\u6a21\u578b\uff08Memory Model\uff09<\/h3>\n<p>\u5185\u5b58\u6a21\u578b\u8fd9\u4e00\u8282\u6bd4\u8f83\u957f\uff0c\u8bf7\u8010\u5fc3\u9605\u8bfb<\/p>\n<p>\u5185\u5b58\u6a21\u578b\u63cf\u8ff0\u7684\u662f\u7a0b\u5e8f\u5728 JVM \u7684\u6267\u884c\u8fc7\u7a0b\u4e2d\u5bf9\u6570\u636e\u7684\u8bfb\u5199\u662f\u5426\u662f\u6309\u7167\u7a0b\u5e8f\u7684\u89c4\u5219\u6b63\u786e\u6267\u884c\u7684\u3002Java \u5185\u5b58\u6a21\u578b\u5b9a\u4e49\u4e86\u4e00\u7cfb\u5217\u89c4\u5219\uff0c\u8fd9\u4e9b\u89c4\u5219\u5b9a\u4e49\u4e86\u5bf9\u5171\u4eab\u5185\u5b58\u7684\u5199\u64cd\u4f5c\u5bf9\u4e8e\u8bfb\u64cd\u4f5c\u7684\u53ef\u89c1\u6027\u3002<\/p>\n<blockquote><p>\u7b80\u5355\u5730\u8bf4\uff0c\u5b9a\u4e49\u5185\u5b58\u6a21\u578b\uff0c\u4e3b\u8981\u5c31\u662f\u4e3a\u4e86\u89c4\u8303\u591a\u7ebf\u7a0b\u7a0b\u5e8f\u4e2d\u4fee\u6539\u6216\u8005\u8bbf\u95ee\u540c\u4e00\u4e2a\u503c\u7684\u65f6\u5019\u7684\u884c\u4e3a\u3002\u5bf9\u4e8e\u90a3\u4e9b\u672c\u8eab\u5c31\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\u95ee\u9898\uff0c\u8fd9\u91cc\u4e0d\u505a\u8ba8\u8bba\u3002<\/p><\/blockquote>\n<p>\u5185\u5b58\u6a21\u578b\u63cf\u8ff0\u4e86\u7a0b\u5e8f\u6267\u884c\u65f6\u7684\u53ef\u80fd\u7684\u8868\u73b0\u884c\u4e3a\u3002\u53ea\u8981\u6267\u884c\u7684\u7ed3\u679c\u662f\u6ee1\u8db3 java \u5185\u5b58\u6a21\u578b\u7684\u6240\u6709\u89c4\u5219\uff0c\u90a3\u4e48\u865a\u62df\u673a\u5bf9\u4e8e\u5177\u4f53\u7684\u5b9e\u73b0\u53ef\u4ee5\u81ea\u7531\u53d1\u6325\u3002<\/p>\n<blockquote><p>\u4ece\u4fa7\u9762\u8bf4\uff0c\u4e0d\u7ba1\u865a\u62df\u673a\u7684\u5b9e\u73b0\u662f\u600e\u4e48\u6837\u7684\uff0c\u591a\u7ebf\u7a0b\u7a0b\u5e8f\u7684\u6267\u884c\u7ed3\u679c\u90fd\u5e94\u8be5\u662f\u53ef\u9884\u6d4b\u7684\u3002<\/p><\/blockquote>\n<p>\u865a\u62df\u673a\u5b9e\u73b0\u8005\u53ef\u4ee5\u81ea\u7531\u5730\u6267\u884c\u5927\u91cf\u7684\u4ee3\u7801\u8f6c\u6362\uff0c\u5305\u62ec\u91cd\u6392\u5e8f\u64cd\u4f5c\u548c\u5220\u9664\u4e00\u4e9b\u4e0d\u5fc5\u8981\u7684\u540c\u6b65\u3002<\/p>\n<p>\u8fd9\u91cc\u6211\u753b\u4e86\u4e00\u6761\u7ebf\uff0c\u4ece\u8fd9\u6761\u7ebf\u5230\u4e0b\u4e00\u6761\u7ebf\u4e4b\u95f4\u662f\u4e24\u4e2a\u91cd\u6392\u5e8f\u7684\u4f8b\u5b50\uff0c\u5982\u679c\u4f60\u6ca1\u63a5\u89e6\u8fc7\uff0c\u53ef\u4ee5\u770b\u4e00\u4e0b\uff0c\u5982\u679c\u4f60\u5df2\u7ecf\u719f\u6089\u4e86\u6216\u8005\u5728\u5176\u4ed6\u5730\u65b9\u770b\u8fc7\u4e86\uff0c\u8bf7\u76f4\u63a5\u5f80\u4e0b\u6ed1\u3002<\/p>\n<p><strong>\u793a\u4f8b 17.4-1 \u4e0d\u6b63\u786e\u7684\u540c\u6b65\u53ef\u80fd\u5bfc\u81f4\u5947\u602a\u7684\u7ed3\u679c<\/strong><\/p>\n<p>java\u8bed\u8a00\u5141\u8bb8 compilers \u548c CPU \u5bf9\u6267\u884c\u6307\u4ee4\u8fdb\u884c\u91cd\u6392\u5e8f\uff0c\u5bfc\u81f4\u6211\u4eec\u4f1a\u7ecf\u5e38\u770b\u5230\u4f3c\u662f\u800c\u975e\u7684\u73b0\u8c61\u3002<\/p>\n<blockquote><p>\u8fd9\u91cc\u6ca1\u6709\u7ffb\u8bd1 compiler \u4e3a\u7f16\u8bd1\u5668\uff0c\u56e0\u4e3a\u5b83\u4e0d\u4ec5\u4ec5\u4ee3\u8868\u7f16\u8bd1\u5668\uff0c\u540e\u7eed\u5b83\u4f1a\u4ee3\u8868\u6240\u6709\u4f1a\u5bfc\u81f4\u6307\u4ee4\u91cd\u6392\u5e8f\u7684\u673a\u5236\u3002<\/p><\/blockquote>\n<p>\u5982\u8868 17.4-A \u4e2d\u6240\u793a\uff0cA \u548c B \u662f\u5171\u4eab\u5c5e\u6027\uff0cr1 \u548c r2 \u662f\u5c40\u90e8\u53d8\u91cf\u3002\u521d\u59cb\u65f6\uff0c\u4ee4 A == B == 0\u3002<\/p>\n<p>\u886817.4-A. \u91cd\u6392\u5e8f\u5bfc\u81f4\u5947\u602a\u7684\u7ed3\u679c &#8211; \u539f\u59cb\u4ee3\u7801<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/bVc1zMC\" alt=\"\" title=\"\" loading=\"lazy\">\u6309\u7167\u6211\u4eec\u7684\u76f4\u89c9\u6765\u8bf4\uff0cr2 == 2 \u540c\u65f6 r1 == 1 \u5e94\u8be5\u662f\u4e0d\u53ef\u80fd\u7684\u3002\u76f4\u89c2\u5730\u8bf4\uff0c\u6307\u4ee4 1 \u548c 3 \u5e94\u8be5\u662f\u6700\u5148\u6267\u884c\u7684\u3002\u5982\u679c\u6307\u4ee4 1 \u6700\u5148\u6267\u884c\uff0c\u90a3\u4e48\u5b83\u5e94\u8be5\u4e0d\u4f1a\u770b\u5230\u6307\u4ee4 4 \u5bf9 A \u7684\u5199\u5165\u64cd\u4f5c\u3002\u5982\u679c\u6307\u4ee4 3 \u6700\u5148\u6267\u884c\uff0c\u90a3\u4e48\u5b83\u5e94\u8be5\u4e0d\u4f1a\u770b\u5230\u6267\u884c 2 \u5bf9 B \u7684\u5199\u5165\u64cd\u4f5c\u3002<\/p>\n<p>\u5982\u679c\u771f\u7684\u8868\u73b0\u51fa\u4e86 r2==2 \u548c r1==1\uff0c\u90a3\u4e48\u6211\u4eec\u5e94\u8be5\u77e5\u9053\uff0c\u6307\u4ee4 4 \u5148\u4e8e\u6307\u4ee4 1 \u6267\u884c\u4e86\u3002<\/p>\n<p>\u5982\u679c\u5728\u6267\u884c\u8fc7\u7a0b\u51fa\u8868\u73b0\u51fa\u8fd9\u79cd\u884c\u4e3a\uff08 r2==2 \u548cr1==1\uff09\uff0c\u90a3\u4e48\u6211\u4eec\u53ef\u4ee5\u63a8\u65ad\u51fa\u4ee5\u4e0b\u6307\u4ee4\u4f9d\u6b21\u6267\u884c\uff1a\u6307\u4ee4 4 =&gt; \u6307\u4ee4 1=&gt; \u6307\u4ee4 2 =&gt; \u6307\u4ee4 3\u3002\u770b\u4e0a\u53bb\uff0c\u8fd9\u79cd\u987a\u5e8f\u662f\u8352\u8c2c\u7684\u3002<\/p>\n<p>\u4f46\u662f\uff0cJava \u662f\u5141\u8bb8 compilers \u5bf9\u6307\u4ee4\u8fdb\u884c\u91cd\u6392\u5e8f\u7684\uff0c\u53ea\u8981\u4fdd\u8bc1\u5728\u5355\u7ebf\u7a0b\u7684\u60c5\u51b5\u4e0b\uff0c\u80fd\u4fdd\u8bc1\u7a0b\u5e8f\u662f\u6309\u7167\u6211\u4eec\u60f3\u8981\u7684\u7ed3\u679c\u8fdb\u884c\u6267\u884c\uff0c\u5373 compilers \u53ef\u4ee5\u5bf9<strong>\u5355\u7ebf\u7a0b\u5185\u4e0d\u4ea7\u751f\u6570\u636e\u4f9d\u8d56\u7684\u8bed\u53e5\u4e4b\u95f4\u8fdb\u884c\u91cd\u6392\u5e8f<\/strong>\u3002\u5982\u679c\u6307\u4ee4 1 \u548c\u6307\u4ee4 2 \u53d1\u751f\u4e86\u91cd\u6392\u5e8f\uff0c\u5982\u6309\u7167\u886817.4-B \u6240\u793a\u7684\u987a\u5e8f\u8fdb\u884c\u6267\u884c\uff0c\u90a3\u4e48\u6211\u4eec\u5c31\u5f88\u5bb9\u6613\u770b\u5230\uff0cr2==2 \u548c r1==1 \u662f\u53ef\u80fd\u53d1\u751f\u7684\u3002<\/p>\n<p>\u8868 17.4-B. \u91cd\u6392\u5e8f\u5bfc\u81f4\u5947\u602a\u7684\u7ed3\u679c &#8211; \u5141\u8bb8\u7684\u7f16\u8bd1\u5668\u8f6c\u6362<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/bVc1zMD\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<blockquote><p>B = 1;  =&gt;  r1 = B;  =&gt;  A = 2;  =&gt;  r2 = A;<\/p><\/blockquote>\n<p>\u5bf9\u4e8e\u5f88\u591a\u7a0b\u5e8f\u5458\u6765\u8bf4\uff0c\u8fd9\u4e2a\u7ed3\u679c\u770b\u4e0a\u53bb\u662f broken \u7684\uff0c\u4f46\u662f\u8fd9\u6bb5\u4ee3\u7801\u662f\u6ca1\u6709\u6b63\u786e\u7684\u540c\u6b65\u5bfc\u81f4\u7684\uff1a<\/p>\n<ul>\n<li>\u5176\u4e2d\u6709\u4e00\u4e2a\u7ebf\u7a0b\u6267\u884c\u4e86\u5199\u64cd\u4f5c<\/li>\n<li>\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u5bf9\u540c\u4e00\u4e2a\u5c5e\u6027\u6267\u884c\u4e86\u8bfb\u64cd\u4f5c<\/li>\n<li>\u540c\u65f6\uff0c\u8bfb\u64cd\u4f5c\u548c\u5199\u64cd\u4f5c\u6ca1\u6709\u4f7f\u7528\u540c\u6b65\u6765\u786e\u5b9a\u5b83\u4eec\u4e4b\u95f4\u7684\u6267\u884c\u987a\u5e8f<\/li>\n<\/ul>\n<blockquote><p>\u7b80\u5355\u5730\u8bf4\uff0c\u4e4b\u540e\u8981\u8bb2\u7684\u4e00\u5927\u5806\u4e1c\u897f\u4e3b\u8981\u5c31\u662f\u4e3a\u4e86\u786e\u5b9a\u5171\u4eab\u5185\u5b58\u8bfb\u5199\u7684\u6267\u884c\u987a\u5e8f\uff0c\u4e0d\u6b63\u786e\u6216\u8005\u8bf4\u975e\u6cd5\u7684\u4ee3\u7801\u5c31\u662f\u56e0\u4e3a\u8bfb\u5199\u540c\u4e00\u5185\u5b58\u5730\u5740\u6ca1\u6709\u4f7f\u7528\u540c\u6b65\uff08\u8fd9\u91cc\u4e0d\u4ec5\u4ec5\u53ea\u662f\u8bf4synchronized\uff09\uff0c\u4ece\u800c\u5bfc\u81f4\u6267\u884c\u7684\u7ed3\u679c\u5177\u6709\u4e0d\u786e\u5b9a\u6027\u3002<\/p><\/blockquote>\n<p>\u8fd9\u4e2a\u662f <strong>\u6570\u636e\u7ade\u4e89(data race)<\/strong> \u7684\u4e00\u4e2a\u4f8b\u5b50\u3002\u5f53\u4ee3\u7801\u5305\u542b\u6570\u636e\u7ade\u4e89\u65f6\uff0c\u7ecf\u5e38\u4f1a\u53d1\u751f\u8fdd\u53cd\u6211\u4eec\u76f4\u89c9\u7684\u7ed3\u679c\u3002<\/p>\n<p>\u6709\u51e0\u4e2a\u673a\u5236\u4f1a\u5bfc\u81f4\u8868 17.4-B \u4e2d\u7684\u6307\u4ee4\u91cd\u6392\u5e8f\u3002java \u7684 JIT \u7f16\u8bd1\u5668\u5b9e\u73b0\u53ef\u80fd\u4f1a\u91cd\u6392\u5e8f\u4ee3\u7801\uff0c\u6216\u8005\u5904\u7406\u5668\u4e5f\u4f1a\u505a\u91cd\u6392\u5e8f\u64cd\u4f5c\u3002\u6b64\u5916\uff0cjava \u865a\u62df\u673a\u5b9e\u73b0\u4e2d\u7684\u5185\u5b58\u5c42\u6b21\u7ed3\u6784\u4e5f\u4f1a\u4f7f\u4ee3\u7801\u50cf\u91cd\u6392\u5e8f\u4e00\u6837\u3002\u5728\u672c\u7ae0\u4e2d\uff0c\u6211\u4eec\u5c06\u6240\u6709\u8fd9\u4e9b\u4f1a\u5bfc\u81f4\u4ee3\u7801\u91cd\u6392\u5e8f\u7684\u4e1c\u897f\u7edf\u79f0\u4e3a compiler\u3002<\/p>\n<blockquote><p>\u6240\u4ee5\uff0c\u540e\u7eed\u6211\u4eec\u4e0d\u8981\u518d\u7b80\u5355\u5730\u5c06 compiler \u7ffb\u8bd1\u4e3a\u7f16\u8bd1\u5668\uff0c\u4e0d\u8981\u72ed\u9698\u5730\u7406\u89e3\u4e3a Java \u7f16\u8bd1\u5668\u3002\u800c\u662f\u4ee3\u8868\u4e86\u6240\u6709\u53ef\u80fd\u4f1a\u5236\u9020\u91cd\u6392\u5e8f\u7684\u673a\u5236\uff0c\u5305\u62ec JVM \u4f18\u5316\u3001CPU \u4f18\u5316\u7b49\u3002<\/p><\/blockquote>\n<p>\u53e6\u4e00\u4e2a\u53ef\u80fd\u4ea7\u751f\u5947\u602a\u7684\u7ed3\u679c\u7684\u793a\u4f8b\u5982\u8868 17.4-C\uff0c\u521d\u59cb\u65f6 p == q \u540c\u65f6 p.x == 0\u3002\u8fd9\u4e2a\u4ee3\u7801\u4e5f\u662f\u6ca1\u6709\u6b63\u786e\u4f7f\u7528\u540c\u6b65\u7684\uff1b\u5728\u8fd9\u4e9b\u5199\u5165\u5171\u4eab\u5185\u5b58\u7684\u5199\u64cd\u4f5c\u4e2d\uff0c\u6ca1\u6709\u8fdb\u884c\u5f3a\u5236\u7684\u5148\u540e\u6392\u5e8f\u3002<\/p>\n<p><strong>Table 17.4-C<\/strong><\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/bVc1zME\" alt=\"\" title=\"\" loading=\"lazy\">\u4e00\u4e2a\u7b80\u5355\u7684\u7f16\u8bd1\u5668\u4f18\u5316\u64cd\u4f5c\u662f\u4f1a\u590d\u7528 r2 \u7684\u7ed3\u679c\u7ed9 r5\uff0c\u56e0\u4e3a\u5b83\u4eec\u90fd\u662f\u8bfb\u53d6 r1.x\uff0c\u800c\u4e14\u5728\u5355\u7ebf\u7a0b\u8bed\u4e49\u4e2d\uff0cr2 \u5230 r5\u4e4b\u95f4\u6ca1\u6709\u5176\u4ed6\u7684\u76f8\u5173\u7684\u5199\u5165\u64cd\u4f5c\uff0c\u8fd9\u79cd\u60c5\u51b5\u5982\u8868 17.4-D \u6240\u793a\u3002<\/p>\n<p><strong>Table 17.4-D<\/strong><\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/bVc1zMF\" alt=\"\" title=\"\" loading=\"lazy\">\u73b0\u5728\uff0c\u6211\u4eec\u6765\u8003\u8651\u4e00\u79cd\u60c5\u51b5\uff0c\u5728\u7ebf\u7a0b1\u7b2c\u4e00\u6b21\u8bfb\u53d6 r1.x \u548c r3.x \u4e4b\u95f4\uff0c\u7ebf\u7a0b 2 \u6267\u884c r6=p; r6.x=3; \u7f16\u8bd1\u5668\u8fdb\u884c\u4e86 r5\u590d\u7528 r2 \u7ed3\u679c\u7684\u4f18\u5316\u64cd\u4f5c\uff0c\u90a3\u4e48 r2==r5==0\uff0cr4 == 3\uff0c\u4ece\u7a0b\u5e8f\u5458\u7684\u89d2\u5ea6\u6765\u770b\uff0cp.x \u7684\u503c\u7531 0 \u53d8\u4e3a 3\uff0c\u7136\u540e\u53c8\u53d8\u4e3a 0\u3002<\/p>\n<blockquote><p>\u6211\u7b80\u5355\u6574\u7406\u4e86\u4e00\u4e0b\uff1a<\/p><\/blockquote>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/bVc1zMG\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<blockquote><p>\u4f8b\u5b50\u7ed3\u675f\uff0c\u56de\u5230\u6b63\u9898<\/p><\/blockquote>\n<p>Java \u5185\u5b58\u6a21\u578b\u5b9a\u4e49\u4e86\u5728\u7a0b\u5e8f\u7684\u6bcf\u4e00\u6b65\uff0c\u54ea\u4e9b\u503c\u662f\u5185\u5b58\u53ef\u89c1\u7684\u3002\u5bf9\u4e8e\u9694\u79bb\u7684\u6bcf\u4e2a\u7ebf\u7a0b\u6765\u8bf4\uff0c\u5176\u64cd\u4f5c\u662f\u7531\u6211\u4eec\u7ebf\u7a0b\u4e2d\u7684\u8bed\u4e49\u6765\u51b3\u5b9a\u7684\uff0c\u4f46\u662f\u7ebf\u7a0b\u4e2d\u8bfb\u53d6\u5230\u7684\u503c\u662f\u7531\u5185\u5b58\u6a21\u578b\u6765\u63a7\u5236\u7684\u3002<\/p>\n<p>\u5f53\u6211\u4eec\u63d0\u5230\u8fd9\u70b9\u65f6\uff0c\u6211\u4eec\u8bf4\u7a0b\u5e8f\u9075\u5b88\u7ebf\u7a0b\u5185\u8bed\u4e49\uff0c\u7ebf\u7a0b\u5185\u8bed\u4e49\u8bf4\u7684\u662f\u5355\u7ebf\u7a0b\u5185\u7684\u8bed\u4e49\uff0c\u5b83\u5141\u8bb8\u6211\u4eec\u57fa\u4e8e\u7ebf\u7a0b\u5185\u8bfb\u64cd\u4f5c\u770b\u5230\u7684\u503c\u5b8c\u5168\u9884\u6d4b\u7ebf\u7a0b\u7684\u884c\u4e3a\u3002\u5982\u679c\u6211\u4eec\u8981\u786e\u5b9a\u7ebf\u7a0b t \u4e2d\u7684\u64cd\u4f5c\u662f\u5426\u662f\u5408\u6cd5\u7684\uff0c\u6211\u4eec\u53ea\u8981\u8bc4\u4f30\u5f53\u7ebf\u7a0b t \u5728\u5355\u7ebf\u7a0b\u73af\u5883\u4e2d\u8fd0\u884c\u65f6\u662f\u5426\u662f\u5408\u6cd5\u7684\u5c31\u53ef\u4ee5\uff0c\u8be5\u89c4\u8303\u7684\u5176\u4f59\u90e8\u5206\u4e5f\u5728\u5b9a\u4e49\u8fd9\u4e2a\u95ee\u9898\u3002<\/p>\n<blockquote><p>\u8fd9\u6bb5\u8bdd\u4e0d\u592a\u597d\u7406\u89e3\uff0c\u9996\u5148\u8bb0\u4f4f\u201c\u7ebf\u7a0b\u5185\u8bed\u4e49\u201d\u8fd9\u4e2a\u6982\u5ff5\uff0c\u4e4b\u540e\u8fd8\u4f1a\u7528\u5230\u3002\u6211\u5bf9\u8fd9\u6bb5\u8bdd\u7684\u7406\u89e3\u662f\uff0c\u5728\u5355\u7ebf\u7a0b\u4e2d\uff0c\u6211\u4eec\u662f\u53ef\u4ee5\u901a\u8fc7\u4e00\u884c\u4e00\u884c\u770b\u4ee3\u7801\u6765\u9884\u6d4b\u6267\u884c\u7ed3\u679c\u7684\uff0c\u53ea\u4e0d\u8fc7\uff0c\u4ee3\u7801\u4e2d\u4f7f\u7528\u5230\u7684\u8bfb\u53d6\u5185\u5b58\u7684\u503c\u6211\u4eec\u662f\u4e0d\u80fd\u786e\u5b9a\u7684\uff0c\u8fd9\u53d6\u51b3\u4e8e\u5728\u5185\u5b58\u6a21\u578b\u8fd9\u4e2a\u5927\u6846\u67b6\u4e0b\uff0c\u6211\u4eec\u7684\u7a0b\u5e8f\u4f1a\u8bfb\u5230\u7684\u503c\u3002\u4e5f\u8bb8\u662f\u6700\u65b0\u7684\u503c\uff0c\u4e5f\u8bb8\u662f\u8fc7\u65f6\u7684\u503c\u3002<\/p><\/blockquote>\n<p>\u6b64\u8282\u63cf\u8ff0\u9664\u4e86 final \u5173\u952e\u5b57\u5916\u7684java\u5185\u5b58\u6a21\u578b\u7684\u89c4\u8303\uff0cfinal\u5c06\u5728\u4e4b\u540e\u768417.5\u8282\u4ecb\u7ecd\u3002<\/p>\n<p><em>\u8fd9\u91cc\u63cf\u8ff0\u7684\u5185\u5b58\u6a21\u578b\u5e76\u4e0d\u662f\u57fa\u4e8e  Java \u7f16\u7a0b\u8bed\u8a00\u7684\u9762\u5411\u5bf9\u8c61\u3002\u4e3a\u4e86\u7b80\u6d01\u8d77\u89c1\uff0c\u6211\u4eec\u7ecf\u5e38\u5c55\u793a\u6ca1\u6709\u7c7b\u6216\u65b9\u6cd5\u5b9a\u4e49\u7684\u4ee3\u7801\u7247\u6bb5\u3002\u5927\u591a\u6570\u793a\u4f8b\u5305\u542b\u4e24\u4e2a\u6216\u591a\u4e2a\u7ebf\u7a0b\uff0c\u5176\u4e2d\u5305\u542b\u5c40\u90e8\u53d8\u91cf\uff0c\u5171\u4eab\u5168\u5c40\u53d8\u91cf\u6216\u5bf9\u8c61\u7684\u5b9e\u4f8b\u5b57\u6bb5\u7684\u8bed\u53e5\u3002\u6211\u4eec\u901a\u5e38\u4f7f\u7528\u8bf8\u5982 r1 \u6216 r2 \u4e4b\u7c7b\u7684\u53d8\u91cf\u540d\u6765\u8868\u793a\u65b9\u6cd5\u6216\u7ebf\u7a0b\u672c\u5730\u7684\u53d8\u91cf\u3002\u5176\u4ed6\u7ebf\u7a0b\u65e0\u6cd5\u8bbf\u95ee\u6b64\u7c7b\u53d8\u91cf\u3002<\/em><\/p>\n<h4>17.4.1. \u5171\u4eab\u53d8\u91cf\uff08Shared Variables\uff09<\/h4>\n<p>\u6240\u6709\u7ebf\u7a0b\u90fd\u53ef\u4ee5\u8bbf\u95ee\u5230\u7684\u5185\u5b58\u79f0\u4e3a<strong>\u5171\u4eab\u5185\u5b58<\/strong>\u6216<strong>\u5806\u5185\u5b58<\/strong>\u3002<\/p>\n<p>\u6240\u6709\u7684\u5b9e\u4f8b\u5c5e\u6027\uff0c\u9759\u6001\u5c5e\u6027\uff0c\u8fd8\u6709\u6570\u7ec4\u7684\u5143\u7d20\u90fd\u5b58\u50a8\u5728\u5806\u5185\u5b58\u4e2d\u3002\u5728\u672c\u7ae0\u4e2d\uff0c\u6211\u4eec\u7528\u672f\u8bed\u53d8\u91cf\u6765\u8868\u793a\u8fd9\u4e9b\u5143\u7d20\u3002<\/p>\n<p>\u5c40\u90e8\u53d8\u91cf\u3001\u65b9\u6cd5\u53c2\u6570\u3001\u5f02\u5e38\u5bf9\u8c61\uff0c\u5b83\u4eec\u4e0d\u4f1a\u5728\u7ebf\u7a0b\u95f4\u5171\u4eab\uff0c\u4e5f\u4e0d\u4f1a\u53d7\u5230\u5185\u5b58\u6a21\u578b\u5b9a\u4e49\u7684\u4efb\u4f55\u5f71\u54cd\u3002<\/p>\n<p>\u4e24\u4e2a\u7ebf\u7a0b\u5bf9\u540c\u4e00\u4e2a\u53d8\u91cf\u540c\u65f6\u8fdb\u884c<strong>\u8bfb-\u5199\u64cd\u4f5c<\/strong>\u6216<strong>\u5199-\u5199\u64cd\u4f5c<\/strong>\uff0c\u6211\u4eec\u79f0\u4e4b\u4e3a\u201c\u51b2\u7a81\u201d\u3002<\/p>\n<blockquote><p>\u597d\uff0c\u8fd9\u4e00\u8282\u90fd\u662f\u5e9f\u8bdd\uff0c\u6109\u5feb\u5730\u8fdb\u5165\u5230\u4e0b\u4e00\u8282<\/p><\/blockquote>\n<h4>17.4.2. \u64cd\u4f5c\uff08Actions\uff09<\/h4>\n<p>\u8fd9\u4e00\u8282\u4e3b\u8981\u662f\u8bb2\u89e3\u7406\u8bba\uff0c\u4e3b\u8981\u5c31\u662f\u4e25\u8c28\u5730\u5b9a\u4e49\u64cd\u4f5c\u3002<\/p>\n<p>\u7ebf\u7a0b\u95f4\u64cd\u4f5c\u662f\u6307\u7531\u4e00\u4e2a\u7ebf\u7a0b\u6267\u884c\u7684\u52a8\u4f5c\uff0c\u53ef\u4ee5\u88ab\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u68c0\u6d4b\u5230\u6216\u76f4\u63a5\u5f71\u54cd\u5230\u3002\u4ee5\u4e0b\u662f\u51e0\u79cd\u53ef\u80fd\u53d1\u751f\u7684\u7ebf\u7a0b\u95f4\u64cd\u4f5c\uff1a<\/p>\n<ul>\n<li>\u8bfb \uff08\u666e\u901a\u53d8\u91cf\uff0c\u975e volatile\uff09\u3002\u8bfb\u4e00\u4e2a\u53d8\u91cf\u3002<\/li>\n<li>\u5199 \uff08\u666e\u901a\u53d8\u91cf\uff0c\u975e volatile\uff09\u3002\u5199\u4e00\u4e2a\u53d8\u91cf\u3002<\/li>\n<li>\u540c\u6b65\u64cd\u4f5c\uff0c\u5982\u4e0b\uff1a<\/li>\n<li>\n<ul>\n<li>volatile \u8bfb\u3002\u8bfb\u4e00\u4e2a volatile \u53d8\u91cf<\/li>\n<li>volatile \u5199\u3002\u5199\u5165\u4e00\u4e2a volatile \u53d8\u91cf<\/li>\n<li>\u52a0\u9501\u3002\u5bf9\u4e00\u4e2a\u5bf9\u8c61\u7684\u76d1\u89c6\u5668\u52a0\u9501\u3002<\/li>\n<li>\u89e3\u9501\u3002\u89e3\u9664\u5bf9\u67d0\u4e2a\u5bf9\u8c61\u7684\u76d1\u89c6\u5668\u9501\u3002<\/li>\n<li>\u7ebf\u7a0b\u7684\u7b2c\u4e00\u4e2a\u548c\u6700\u540e\u4e00\u4e2a\u64cd\u4f5c\u3002<\/li>\n<li>\u5f00\u542f\u7ebf\u7a0b\u64cd\u4f5c\uff0c\u6216\u68c0\u6d4b\u4e00\u4e2a\u7ebf\u7a0b\u662f\u5426\u5df2\u7ecf\u7ed3\u675f\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u5916\u90e8\u64cd\u4f5c<\/strong>\u3002\u4e00\u4e2a\u5916\u90e8\u64cd\u4f5c\u6307\u7684\u662f\u53ef\u80fd\u88ab\u89c2\u5bdf\u5230\u7684\u5728\u5916\u90e8\u6267\u884c\u7684\u64cd\u4f5c\uff0c\u540c\u65f6\u5b83\u7684\u6267\u884c\u7ed3\u679c\u53d7\u5916\u90e8\u73af\u5883\u63a7\u5236\u3002<\/li>\n<\/ul>\n<p>\u7b80\u5355\u8bf4\uff0c\u5916\u90e8\u64cd\u4f5c\u7684\u5916\u90e8\u6307\u7684\u662f\u5728 JVM \u4e4b\u5916\uff0c\u5982 native \u64cd\u4f5c\u3002<\/p>\n<ul>\n<li><strong>\u7ebf\u7a0b\u5206\u6b67\u64cd\u4f5c(\u00a717.4.9)<\/strong>\u3002\u6b64\u64cd\u4f5c\u53ea\u7531\u5904\u4e8e\u65e0\u9650\u5faa\u73af\u7684\u7ebf\u7a0b\u6267\u884c\uff0c\u5728\u8be5\u5faa\u73af\u4e2d\u4e0d\u6267\u884c\u4efb\u4f55\u5185\u5b58\u64cd\u4f5c\u3001\u540c\u6b65\u64cd\u4f5c\u3001\u6216\u5916\u90e8\u64cd\u4f5c\u3002\u5982\u679c\u4e00\u4e2a\u7ebf\u7a0b\u6267\u884c\u4e86\u5206\u6b67\u64cd\u4f5c\uff0c\u90a3\u4e48\u5176\u540e\u5c06\u8ddf\u7740\u65e0\u6570\u7684\u7ebf\u7a0b\u5206\u6b67\u64cd\u4f5c\u3002<\/li>\n<\/ul>\n<p>\u5206\u6b67\u64cd\u4f5c\u7684\u5f15\u5165\u662f\u4e3a\u4e86\u7528\u6765\u8bf4\u660e\uff0c\u7ebf\u7a0b\u53ef\u80fd\u4f1a\u5bfc\u81f4\u5176\u4ed6\u6240\u6709\u7ebf\u7a0b\u505c\u987f\u800c\u4e0d\u80fd\u7ee7\u7eed\u6267\u884c\u3002<\/p>\n<p>\u6b64\u89c4\u8303\u4ec5\u5173\u5fc3\u7ebf\u7a0b\u95f4\u64cd\u4f5c\uff0c\u6211\u4eec\u4e0d\u5173\u5fc3\u7ebf\u7a0b\u5185\u90e8\u7684\u64cd\u4f5c\uff08\u6bd4\u5982\u5c06\u4e24\u4e2a\u5c40\u90e8\u53d8\u91cf\u7684\u503c\u76f8\u52a0\u5b58\u5230\u7b2c\u4e09\u4e2a\u5c40\u90e8\u53d8\u91cf\u4e2d\uff09\u3002\u5982\u524d\u6587\u6240\u8bf4\uff0c\u6240\u6709\u7684\u7ebf\u7a0b\u90fd\u9700\u8981\u9075\u5b88\u7ebf\u7a0b\u5185\u8bed\u4e49\u3002\u5bf9\u4e8e\u7ebf\u7a0b\u95f4\u64cd\u4f5c\uff0c\u6211\u4eec\u7ecf\u5e38\u4f1a\u7b80\u5355\u5730\u79f0\u4e3a\u64cd\u4f5c\u3002<\/p>\n<p>\u6211\u4eec\u7528\u5143\u7956&lt; t, k, v, u &gt;\u6765\u63cf\u8ff0\u4e00\u4e2a\u64cd\u4f5c\uff1a<\/p>\n<ul>\n<li>t &#8211; \u6267\u884c\u64cd\u4f5c\u7684\u7ebf\u7a0b<\/li>\n<li>k &#8211; \u64cd\u4f5c\u7684\u7c7b\u578b\u3002<\/li>\n<li>v &#8211; \u64cd\u4f5c\u6d89\u53ca\u7684\u53d8\u91cf\u6216\u76d1\u89c6\u5668<\/li>\n<li>\n<ul>\n<li>\u5bf9\u4e8e\u52a0\u9501\u64cd\u4f5c\uff0cv \u662f\u88ab\u9501\u4f4f\u7684\u76d1\u89c6\u5668\uff1b\u5bf9\u4e8e\u89e3\u9501\u64cd\u4f5c\uff0cv \u662f\u88ab\u89e3\u9501\u7684\u76d1\u89c6\u5668\u3002<\/li>\n<li>\u5982\u679c\u662f\u4e00\u4e2a\u8bfb\u64cd\u4f5c\uff08 volatile \u8bfb\u6216\u975e volatile \u8bfb\uff09\uff0cv \u662f\u8bfb\u64cd\u4f5c\u5bf9\u5e94\u7684\u53d8\u91cf<\/li>\n<li>\u5982\u679c\u662f\u4e00\u4e2a\u5199\u64cd\u4f5c( volatile \u5199\u6216\u975e volatile \u5199)\uff0cv \u662f\u5199\u64cd\u4f5c\u5bf9\u5e94\u7684\u53d8\u91cf<\/li>\n<\/ul>\n<\/li>\n<li>u &#8211; \u552f\u4e00\u7684\u6807\u8bc6\u7b26\u6807\u8bc6\u6b64\u64cd\u4f5c<\/li>\n<\/ul>\n<p>\u5916\u90e8\u52a8\u4f5c\u5143\u7ec4\u8fd8\u5305\u542b\u4e00\u4e2a\u9644\u52a0\u7ec4\u4ef6\uff0c\u5176\u4e2d\u5305\u542b\u7531\u6267\u884c\u64cd\u4f5c\u7684\u7ebf\u7a0b\u611f\u77e5\u7684\u5916\u90e8\u64cd\u4f5c\u7684\u7ed3\u679c\u3002\u8fd9\u53ef\u80fd\u662f\u5173\u4e8e\u64cd\u4f5c\u7684\u6210\u8d25\u7684\u4fe1\u606f\uff0c\u4ee5\u53ca\u64cd\u4f5c\u4e2d\u6240\u8bfb\u7684\u4efb\u4f55\u503c\u3002<\/p>\n<p>\u5916\u90e8\u64cd\u4f5c\u7684\u53c2\u6570\uff08\u5982\u54ea\u4e9b\u5b57\u8282\u5199\u5165\u54ea\u4e2a socket\uff09\u4e0d\u662f\u5916\u90e8\u64cd\u4f5c\u5143\u7956\u7684\u4e00\u90e8\u5206\u3002\u8fd9\u4e9b\u53c2\u6570\u662f\u901a\u8fc7\u7ebf\u7a0b\u4e2d\u7684\u5176\u4ed6\u64cd\u4f5c\u8fdb\u884c\u8bbe\u7f6e\u7684\uff0c\u5e76\u53ef\u4ee5\u901a\u8fc7\u68c0\u67e5\u7ebf\u7a0b\u5185\u8bed\u4e49\u8fdb\u884c\u786e\u5b9a\u3002\u5b83\u4eec\u5728\u5185\u5b58\u6a21\u578b\u4e2d\u6ca1\u6709\u88ab\u660e\u786e\u8ba8\u8bba\u3002<\/p>\n<p>\u5728\u975e\u7ec8\u7ed3\u6267\u884c\u4e2d\uff0c\u4e0d\u662f\u6240\u6709\u7684\u5916\u90e8\u64cd\u4f5c\u90fd\u662f\u53ef\u89c2\u5bdf\u7684\u300217.4.9\u5c0f\u8282\u8ba8\u8bba\u975e\u7ec8\u7ed3\u6267\u884c\u548c\u53ef\u89c2\u5bdf\u64cd\u4f5c\u3002<\/p>\n<p>\u5927\u5bb6\u770b\u5b8c\u8fd9\u8282\u6700\u61f5\u903c\u7684\u5e94\u8be5\u662f\u5916\u90e8\u64cd\u4f5c\u548c\u7ebf\u7a0b\u5206\u6b67\u64cd\u4f5c\uff0c\u6211\u7b80\u5355\u89e3\u91ca\u4e0b\u3002<\/p>\n<blockquote><p>\u5916\u90e8\u64cd\u4f5c\u5927\u5bb6\u53ef\u4ee5\u7406\u89e3\u4e3a Java \u8c03\u7528\u4e86\u4e00\u4e2a native \u7684\u65b9\u6cd5\uff0cJava \u53ef\u4ee5\u5f97\u5230\u8fd9\u4e2a native \u65b9\u6cd5\u7684\u8fd4\u56de\u503c\uff0c\u4f46\u662f\u5bf9\u4e8e\u5177\u4f53\u7684\u6267\u884c\u5176\u5b9e\u4e0d\u611f\u77e5\u7684\uff0c\u610f\u5473\u7740 Java \u5176\u5b9e\u4e0d\u80fd\u5bf9\u8fd9\u79cd\u8bed\u53e5\u8fdb\u884c\u91cd\u6392\u5e8f\uff0c\u56e0\u4e3a Java \u65e0\u6cd5\u77e5\u9053\u65b9\u6cd5\u4f53\u4f1a\u6267\u884c\u54ea\u4e9b\u6307\u4ee4\u3002<\/p><\/blockquote>\n<p>\u5f15\u7528 stackoverflow \u4e2d\u7684\u4e00\u4e2a\u4f8b\u5b50\uff1a<\/p>\n<pre><code>\/\/ method()\u65b9\u6cd5\u4e2djni()\u662f\u5916\u90e8\u64cd\u4f5c\uff0c\u4e0d\u4f1a\u548c &quot;foo = 42;&quot; \u8fd9\u6761\u8bed\u53e5\u8fdb\u884c\u91cd\u6392\u5e8f\u3002\nclass Externalization {\n  int foo = 0;\n  void method() {\n    jni(); \/\/ \u5916\u90e8\u64cd\u4f5c\n    foo = 42;\n  }\n  native void jni(); \/* {\n    assert foo == 0; \/\/\u6211\u4eec\u5047\u8bbe\u5916\u90e8\u64cd\u4f5c\u6267\u884c\u7684\u662f\u8fd9\u4e2a\u3002\n  } *\/\n}<\/code><\/pre>\n<blockquote><p>\u5728\u4e0a\u9762\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u663e\u7136\uff0cjni() \u4e0e foo = 42 \u4e4b\u95f4\u4e0d\u80fd\u8fdb\u884c\u91cd\u6392\u5e8f\u3002<\/p><\/blockquote>\n<p>\u518d\u6765\u4e2a\u7ebf\u7a0b\u5206\u6b67\u64cd\u4f5c\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code>\/\/ \u7ebf\u7a0b\u5206\u6b67\u64cd\u4f5c\u963b\u6b62\u4e86\u91cd\u6392\u5e8f\uff0c\u6240\u4ee5 &quot;foo = 42;&quot; \u8fd9\u6761\u8bed\u53e5\u4e0d\u4f1a\u5148\u6267\u884c\nclass ThreadDivergence {\n  int foo = 0;\n  void thread1() {\n    while (true){} \/\/ \u7ebf\u7a0b\u5206\u6b67\u64cd\u4f5c\n    foo = 42;\n  }\n\n  void thread2() {\n    assert foo == 0; \/\/ \u8fd9\u91cc\u6c38\u8fdc\u4e0d\u4f1a\u5931\u8d25\n  }\n}<\/code><\/pre>\n<h4>17.4.3. \u7a0b\u5e8f\u548c\u7a0b\u5e8f\u987a\u5e8f\uff08Programs and Program Order\uff09<\/h4>\n<p>\u5728\u6bcf\u4e2a\u7ebf\u7a0b t \u6267\u884c\u7684\u6240\u6709\u7ebf\u7a0b\u95f4\u52a8\u4f5c\u4e2d\uff0ct \u7684\u7a0b\u5e8f\u987a\u5e8f\u662f\u53cd\u6620 <strong>\u6839\u636e t \u7684\u7ebf\u7a0b\u5185\u8bed\u4e49\u6267\u884c\u8fd9\u4e9b\u52a8\u4f5c\u7684\u987a\u5e8f<\/strong> \u7684\u603b\u987a\u5e8f\u3002<\/p>\n<p><strong>\u5982\u679c\u6240\u6709\u64cd\u4f5c\u7684\u6267\u884c\u987a\u5e8f \u548c \u4ee3\u7801\u4e2d\u7684\u987a\u5e8f\u4e00\u81f4\uff0c\u90a3\u4e48\u4e00\u7ec4\u64cd\u4f5c\u5c31\u662f\u8fde\u7eed\u4e00\u81f4\u7684<\/strong>\uff0c\u5e76\u4e14\uff0c\u5bf9\u53d8\u91cf v \u7684\u6bcf\u4e2a\u8bfb\u64cd\u4f5c r \u4f1a\u770b\u5230\u5199\u64cd\u4f5c w \u5199\u5165\u7684\u503c\uff0c\u4e5f\u5c31\u662f\uff1a<\/p>\n<ul>\n<li>\u5199\u64cd\u4f5c w \u5148\u4e8e \u8bfb\u64cd\u4f5c r \u5b8c\u6210\uff0c\u5e76\u4e14<\/li>\n<li>\u6ca1\u6709\u5176\u4ed6\u7684\u5199\u64cd\u4f5c w&#8217; \u4f7f\u5f97 w&#8217; \u5728 w \u4e4b\u540e r \u4e4b\u524d\u53d1\u751f\u3002<\/li>\n<\/ul>\n<p><strong>\u8fde\u7eed\u4e00\u81f4\u6027<\/strong>\u5bf9\u4e8e\u53ef\u89c1\u6027\u548c\u7a0b\u5e8f\u6267\u884c\u987a\u5e8f\u662f\u4e00\u4e2a\u975e\u5e38\u5f3a\u7684\u4fdd\u8bc1\u3002\u5728\u8fd9\u79cd\u573a\u666f\u4e0b\uff0c\u6240\u6709\u7684\u5355\u4e2a\u64cd\u4f5c\uff08\u6bd4\u5982\u8bfb\u548c\u5199\uff09\u6784\u6210\u4e00\u4e2a\u7edf\u4e00\u7684\u6267\u884c\u987a\u5e8f\uff0c\u8fd9\u4e2a\u6267\u884c\u987a\u5e8f\u548c\u4ee3\u7801\u51fa\u73b0\u7684\u987a\u5e8f\u662f\u4e00\u81f4\u7684\uff0c\u540c\u65f6\u6bcf\u4e2a\u5355\u4e2a\u64cd\u4f5c\u90fd\u662f\u539f\u5b50\u7684\uff0c\u4e14\u5bf9\u6240\u6709\u7ebf\u7a0b\u6765\u8bf4\u7acb\u5373\u53ef\u89c1\u3002<\/p>\n<p>\u5982\u679c\u7a0b\u5e8f\u6ca1\u6709\u4efb\u4f55\u7684\u6570\u636e\u7ade\u4e89\uff0c\u90a3\u4e48\u7a0b\u5e8f\u7684\u6240\u6709\u6267\u884c\u64cd\u4f5c\u5c06\u8868\u73b0\u4e3a\u8fde\u7eed\u4e00\u81f4\u3002\u8fde\u7eed\u4e00\u81f4\u6027 \u548c\/\u6216 \u6570\u636e\u7ade\u4e89\u7684\u81ea\u7531\u4ecd\u7136\u5141\u8bb8\u9519\u8bef\u4ece\u4e00\u7ec4\u64cd\u4f5c\u4e2d\u4ea7\u751f\u3002<\/p>\n<p>\u5b8c\u5168\u4e0d\u77e5\u9053\u8fd9\u53e5\u8bdd\u662f\u4ec0\u4e48\u610f\u601d<\/p>\n<p>\u5982\u679c\u6211\u4eec\u7528\u8fde\u7eed\u4e00\u81f4\u6027\u4f5c\u4e3a\u6211\u4eec\u7684\u5185\u5b58\u6a21\u578b\uff0c\u90a3\u6211\u4eec\u8ba8\u8bba\u7684\u8bb8\u591a\u5173\u4e8e\u7f16\u8bd1\u5668\u4f18\u5316\u548c\u5904\u7406\u5668\u4f18\u5316\u5c31\u662f\u975e\u6cd5\u7684\u3002\u6bd4\u5982\u572817.4-C\u4e2d\uff0c\u4e00\u65e6\u6267\u884c p.x=3\uff0c\u90a3\u4e48\u540e\u7eed\u5bf9\u4e8e\u8be5\u4f4d\u7f6e\u7684\u8bfb\u64cd\u4f5c\u5e94\u8be5\u662f\u7acb\u5373\u53ef\u4ee5\u8bfb\u5230\u6700\u65b0\u503c\u7684\u3002<\/p>\n<blockquote><p>\u8fde\u7eed\u4e00\u81f4\u6027\u7684\u6838\u5fc3\u5728\u4e8e\u6bcf\u4e00\u6b65\u7684\u64cd\u4f5c\u90fd\u662f\u539f\u5b50\u7684\uff0c\u540c\u65f6\u5bf9\u4e8e\u6240\u6709\u7ebf\u7a0b\u90fd\u662f\u53ef\u89c1\u7684\uff0c\u800c\u4e14\u4e0d\u5b58\u5728\u91cd\u6392\u5e8f\u3002\u6240\u4ee5\uff0cJava \u8bed\u8a00\u5b9a\u4e49\u7684\u5185\u5b58\u6a21\u578b\u80af\u5b9a\u4e0d\u4f1a\u91c7\u7528\u8fd9\u79cd\u7b56\u7565\uff0c\u56e0\u4e3a\u5b83\u76f4\u63a5\u9650\u5236\u4e86\u7f16\u8bd1\u5668\u548c JVM \u7684\u5404\u79cd\u4f18\u5316\u63aa\u65bd\u3002<\/p><\/blockquote>\n<p>\u6ce8\u610f\uff1a\u5f88\u591a\u5730\u65b9\u6240\u8bf4\u7684\u987a\u5e8f\u4e00\u81f4\u6027\u5c31\u662f\u8fd9\u91cc\u7684\u8fde\u7eed\u4e00\u81f4\u6027\uff0c\u82f1\u6587\u662f Sequential consistency<\/p>\n<h4>17.4.4. \u540c\u6b65\u987a\u5e8f\uff08Synchronization Order\uff09<\/h4>\n<p>\u6bcf\u4e2a\u6267\u884c\u90fd\u6709\u4e00\u4e2a\u540c\u6b65\u987a\u5e8f\u3002\u540c\u6b65\u987a\u5e8f\u662f\u7531\u6267\u884c\u8fc7\u7a0b\u4e2d\u7684\u6bcf\u4e2a\u540c\u6b65\u64cd\u4f5c\u7ec4\u6210\u7684\u987a\u5e8f\u3002\u5bf9\u4e8e\u6bcf\u4e2a\u7ebf\u7a0b t\uff0c\u540c\u6b65\u64cd\u4f5c\u7ec4\u6210\u7684\u540c\u6b65\u987a\u5e8f\u662f\u548c\u7ebf\u7a0b t \u4e2d\u7684\u4ee3\u7801\u987a\u5e8f\u4e00\u81f4\u7684\u3002<\/p>\n<p>\u867d\u7136\u62d7\u53e3\uff0c\u4f46\u6bd5\u7adf\u8bf4\u7684\u662f\u540c\u6b65\uff0c\u6211\u4eec\u90fd\u4e0d\u964c\u751f\u3002\u540c\u6b65\u64cd\u4f5c\u5305\u62ec\u4e86\u5982\u4e0b\u540c\u6b65\u5173\u7cfb\uff1a<\/p>\n<ul>\n<li>\u5bf9\u4e8e\u76d1\u89c6\u5668 m \u7684\u89e3\u9501\u4e0e\u6240\u6709\u540e\u7eed\u64cd\u4f5c\u5bf9\u4e8e m \u7684\u52a0\u9501\u540c\u6b65<\/li>\n<li>\u5bf9 volatile \u53d8\u91cf v \u7684\u5199\u5165\uff0c\u4e0e\u6240\u6709\u5176\u4ed6\u7ebf\u7a0b\u540e\u7eed\u5bf9 v \u7684\u8bfb\u540c\u6b65<\/li>\n<li>\u542f\u52a8\u7ebf\u7a0b\u7684\u64cd\u4f5c\u4e0e\u7ebf\u7a0b\u4e2d\u7684\u7b2c\u4e00\u4e2a\u64cd\u4f5c\u540c\u6b65\u3002<\/li>\n<li>\u5bf9\u4e8e\u6bcf\u4e2a\u5c5e\u6027\u5199\u5165\u9ed8\u8ba4\u503c\uff080\uff0c false\uff0cnull\uff09\u4e0e\u6bcf\u4e2a\u7ebf\u7a0b\u5bf9\u5176\u8fdb\u884c\u7684\u64cd\u4f5c\u540c\u6b65\u3002<\/li>\n<li>\u5c3d\u7ba1\u5728\u521b\u5efa\u5bf9\u8c61\u5b8c\u6210\u4e4b\u524d\u5bf9\u5bf9\u8c61\u5c5e\u6027\u5199\u5165\u9ed8\u8ba4\u503c\u6709\u70b9\u5947\u602a\uff0c\u4f46\u4ece\u6982\u5ff5\u4e0a\u6765\u8bf4\uff0c\u6bcf\u4e2a\u5bf9\u8c61\u90fd\u662f\u5728\u7a0b\u5e8f\u542f\u52a8\u65f6\u7528\u9ed8\u8ba4\u503c\u521d\u59cb\u5316\u6765\u521b\u5efa\u7684\u3002<\/li>\n<li>\u7ebf\u7a0b T1 \u7684\u6700\u540e\u64cd\u4f5c\u4e0e\u7ebf\u7a0b T2 \u53d1\u73b0\u7ebf\u7a0b T1 \u5df2\u7ecf\u7ed3\u675f\u540c\u6b65\u3002<\/li>\n<li>\u7ebf\u7a0b T2 \u53ef\u4ee5\u901a\u8fc7 T1.isAlive() \u6216 T1.join() \u65b9\u6cd5\u6765\u5224\u65ad T1 \u662f\u5426\u5df2\u7ecf\u7ec8\u7ed3\u3002<\/li>\n<li>\u5982\u679c\u7ebf\u7a0b T1 \u4e2d\u65ad\u4e86 T2\uff0c\u90a3\u4e48\u7ebf\u7a0b T1 \u7684\u4e2d\u65ad\u64cd\u4f5c\u4e0e\u5176\u4ed6\u6240\u6709\u7ebf\u7a0b\u53d1\u73b0 T2 \u88ab\u4e2d\u65ad\u4e86\u540c\u6b65\uff08\u901a\u8fc7\u629b\u51fa InterruptedException \u5f02\u5e38\uff0c\u6216\u8005\u8c03\u7528 Thread.interrupted \u6216 Thread.isInterrupted \uff09<\/li>\n<\/ul>\n<p>\u4ee5\u4e0a\u540c\u6b65\u987a\u5e8f\u53ef\u4ee5\u7406\u89e3\u4e3a\u5bf9\u4e8e\u67d0\u8d44\u6e90\u7684\u91ca\u653e\u5148\u4e8e\u5176\u4ed6\u64cd\u4f5c\u5bf9\u540c\u4e00\u8d44\u6e90\u7684\u83b7\u53d6\u3002<\/p>\n<p>\u597d\uff0c\u8fd9\u8282\u76f8\u5bf9 easy\uff0c\u8bf4\u7684\u5c31\u662f\u5173\u4e8e A synchronizes-with B \u7684\u4e00\u7cfb\u5217\u89c4\u5219\u3002<\/p>\n<h4>17.4.5. Happens-before\u987a\u5e8f\uff08Happens-before Order\uff09<\/h4>\n<blockquote><p>Happens-before \u662f\u975e\u5e38\u91cd\u8981\u7684\u77e5\u8bc6\uff0c\u6709\u4e9b\u5730\u65b9\u6211\u6ca1\u6709\u5f88\u7406\u89e3\uff0c\u6211\u5c3d\u91cf\u5c06\u539f\u6587\u76f4\u8bd1\u8fc7\u6765\u3002\u60f3\u8981\u4e86\u89e3\u66f4\u6df1\u7684\u4e1c\u897f\uff0c\u4f60\u53ef\u80fd\u8fd8\u9700\u8981\u67e5\u8be2\u66f4\u591a\u7684\u5176\u4ed6\u8d44\u6599\u3002<\/p><\/blockquote>\n<p>\u4e24\u4e2a\u64cd\u4f5c\u53ef\u4ee5\u7528 happens-before \u6765\u786e\u5b9a\u5b83\u4eec\u7684\u6267\u884c\u987a\u5e8f\uff0c\u5982\u679c\u4e00\u4e2a\u64cd\u4f5c happens-before \u4e8e\u53e6\u4e00\u4e2a\u64cd\u4f5c\uff0c\u90a3\u4e48\u6211\u4eec\u8bf4\u7b2c\u4e00\u4e2a\u64cd\u4f5c\u5bf9\u4e8e\u7b2c\u4e8c\u4e2a\u64cd\u4f5c\u662f\u53ef\u89c1\u7684\u3002<\/p>\n<blockquote><p>\u6ce8\u610f\uff1ahappens-before \u5f3a\u8c03\u7684\u662f\u53ef\u89c1\u6027\u95ee\u9898<\/p><\/blockquote>\n<p>\u5982\u679c\u6211\u4eec\u5206\u522b\u6709\u64cd\u4f5c x \u548c\u64cd\u4f5c y\uff0c\u6211\u4eec\u5199\u6210 hb(x, y) \u6765\u8868\u793a x happens-before y\u3002<\/p>\n<ul>\n<li>\u5982\u679c\u64cd\u4f5c x \u548c\u64cd\u4f5c y \u662f\u540c\u4e00\u4e2a\u7ebf\u7a0b\u7684\u4e24\u4e2a\u64cd\u4f5c\uff0c\u5e76\u4e14\u5728\u4ee3\u7801\u4e0a\u64cd\u4f5c x \u5148\u4e8e\u64cd\u4f5c y \u51fa\u73b0\uff0c\u90a3\u4e48\u6709 hb(x, y)\u3002\u8bf7\u6ce8\u610f\uff0c\u8fd9\u91cc\u4e0d\u4ee3\u8868\u4e0d\u53ef\u4ee5\u91cd\u6392\u5e8f\uff0c\u53ea\u8981\u6ca1\u6709\u6570\u636e\u4f9d\u8d56\u5173\u7cfb\uff0c\u91cd\u6392\u5e8f\u5c31\u662f\u53ef\u80fd\u7684\u3002<\/li>\n<li>\u5bf9\u8c61\u6784\u9020\u65b9\u6cd5\u7684\u6700\u540e\u4e00\u884c\u6307\u4ee4 happens-before \u4e8e finalize() \u65b9\u6cd5\u7684\u7b2c\u4e00\u884c\u6307\u4ee4\u3002<\/li>\n<li>\u5982\u679c\u64cd\u4f5c x \u4e0e\u968f\u540e\u7684\u64cd\u4f5c y \u6784\u6210\u540c\u6b65\uff0c\u90a3\u4e48 hb(x, y)\u3002<\/li>\n<li>hb(x, y) \u548c hb(y, z)\uff0c\u90a3\u4e48\u53ef\u4ee5\u63a8\u65ad\u51fa hb(x, z)<\/li>\n<\/ul>\n<p>\u5bf9\u8c61\u7684 wait \u65b9\u6cd5\u5173\u8054\u4e86\u52a0\u9501\u548c\u89e3\u9501\u7684\u64cd\u4f5c\uff0c\u5b83\u4eec\u7684 happens-before \u5173\u7cfb\u5373\u662f\u52a0\u9501 happens-before \u89e3\u9501\u3002<\/p>\n<p>\u6211\u4eec\u5e94\u8be5\u6ce8\u610f\u5230\uff0c\u4e24\u4e2a\u64cd\u4f5c\u4e4b\u95f4\u7684 happens-before \u7684\u5173\u7cfb\u5e76\u4e0d\u4e00\u5b9a\u8868\u793a\u5b83\u4eec\u5728 JVM \u7684\u5177\u4f53\u5b9e\u73b0\u4e0a\u5fc5\u987b\u662f\u8fd9\u4e2a\u987a\u5e8f\uff0c\u5982\u679c\u91cd\u6392\u5e8f\u540e\u7684\u64cd\u4f5c\u7ed3\u679c\u548c\u5408\u6cd5\u7684\u6267\u884c\u7ed3\u679c\u662f\u4e00\u81f4\u7684\uff0c\u90a3\u4e48\u8fd9\u79cd\u5b9e\u73b0\u5c31\u4e0d\u662f\u975e\u6cd5\u7684\u3002<\/p>\n<p>\u6bd4\u5982\u8bf4\uff0c\u5728\u7ebf\u7a0b\u4e2d\u5bf9\u5bf9\u8c61\u7684\u6bcf\u4e2a\u5c5e\u6027\u5199\u5165\u521d\u59cb\u9ed8\u8ba4\u503c\u5e76\u4e0d\u9700\u8981\u5148\u4e8e\u7ebf\u7a0b\u7684\u5f00\u59cb\uff0c\u53ea\u8981\u8fd9\u4e2a\u4e8b\u5b9e\u6ca1\u6709\u88ab\u8bfb\u5230\u5c31\u53ef\u4ee5\u4e86\u3002<\/p>\n<blockquote><p>\u6211\u4eec\u53ef\u4ee5\u53d1\u73b0\uff0chappens-before \u89c4\u5219\u4e3b\u8981\u8fd8\u662f\u4e0a\u4e00\u8282 \u540c\u6b65\u987a\u5e8f \u4e2d\u7684\u89c4\u5219\uff0c\u52a0\u4e0a\u989d\u5916\u7684\u51e0\u6761<\/p><\/blockquote>\n<p>\u66f4\u5177\u4f53\u5730\u8bf4\uff0c\u5982\u679c\u4e24\u4e2a\u64cd\u4f5c\u662f happens-before \u7684\u5173\u7cfb\uff0c\u4f46\u662f\u5728\u4ee3\u7801\u4e2d\u5b83\u4eec\u5e76\u6ca1\u6709\u8fd9\u79cd\u987a\u5e8f\uff0c\u90a3\u4e48\u5c31\u6ca1\u6709\u5fc5\u8981\u8868\u73b0\u51fa happens-before \u5173\u7cfb\u3002\u5982\u7ebf\u7a0b 1 \u5bf9\u53d8\u91cf\u8fdb\u884c\u5199\u5165\uff0c\u7ebf\u7a0b 2 \u968f\u540e\u5bf9\u53d8\u91cf\u8fdb\u884c\u8bfb\u64cd\u4f5c\uff0c\u90a3\u4e48\u8fd9\u4e24\u4e2a\u64cd\u4f5c\u662f\u6ca1\u6709 happens-before \u5173\u7cfb\u7684\u3002<\/p>\n<p>happens-before \u5173\u7cfb\u7528\u4e8e\u5b9a\u4e49\u5f53\u53d1\u751f\u6570\u636e\u7ade\u4e89\u7684\u65f6\u5019\u3002\u5c06\u4e0a\u9762\u6240\u6709\u7684\u89c4\u5219\u7b80\u5316\u6210\u4ee5\u4e0b\u5217\u8868\uff1a<\/p>\n<ul>\n<li>\u5bf9\u4e00\u4e2a\u76d1\u89c6\u5668\u7684\u89e3\u9501\u64cd\u4f5c happens-before \u4e8e\u540e\u7eed\u7684\u5bf9\u8fd9\u4e2a\u76d1\u89c6\u5668\u7684\u52a0\u9501\u64cd\u4f5c\u3002<\/li>\n<li>\u5bf9 volatile \u5c5e\u6027\u7684\u5199\u64cd\u4f5c\u5148\u4e8e\u540e\u7eed\u5bf9\u8fd9\u4e2a\u5c5e\u6027\u7684\u8bfb\u64cd\u4f5c\u3002\u4e5f\u5c31\u662f\u4e00\u65e6\u5199\u64cd\u4f5c\u5b8c\u6210\uff0c\u90a3\u4e48\u540e\u7eed\u7684\u8bfb\u64cd\u4f5c\u4e00\u5b9a\u80fd\u8bfb\u5230\u6700\u65b0\u7684\u503c<\/li>\n<li>\u7ebf\u7a0b\u7684 start() \u5148\u4e8e\u4efb\u4f55\u5728\u7ebf\u7a0b\u4e2d\u5b9a\u4e49\u7684\u8bed\u53e5\u3002<\/li>\n<li>\u5982\u679c A \u7ebf\u7a0b\u4e2d\u8c03\u7528\u4e86 B.join()\uff0c\u90a3\u4e48 B \u7ebf\u7a0b\u4e2d\u7684\u64cd\u4f5c\u5148\u4e8e A \u7ebf\u7a0b join() \u8fd4\u56de\u4e4b\u540e\u7684\u4efb\u4f55\u8bed\u53e5\u3002\u56e0\u4e3a join() \u672c\u8eab\u5c31\u662f\u8ba9\u5176\u4ed6\u7ebf\u7a0b\u5148\u6267\u884c\u5b8c\u7684\u610f\u601d\u3002<\/li>\n<li>\u5bf9\u8c61\u7684\u9ed8\u8ba4\u521d\u59cb\u503c happens-before \u4e8e\u7a0b\u5e8f\u4e2d\u5bf9\u5b83\u7684\u5176\u4ed6\u64cd\u4f5c\u3002\u4e5f\u5c31\u662f\u8bf4\u4e0d\u7ba1\u6211\u4eec\u8981\u5bf9\u8fd9\u4e2a\u5bf9\u8c61\u5e72\u4ec0\u4e48\uff0c\u8fd9\u4e2a\u5bf9\u8c61\u5373\u4f7f\u6ca1\u6709\u521b\u5efa\u5b8c\u6210\uff0c\u5b83\u7684\u5404\u4e2a\u5c5e\u6027\u4e5f\u4e00\u5b9a\u6709\u521d\u59cb\u96f6\u503c\u3002<\/li>\n<\/ul>\n<p>\u5f53\u7a0b\u5e8f\u51fa\u73b0\u4e24\u4e2a\u6ca1\u6709 happens-before \u5173\u7cfb\u7684\u64cd\u4f5c\u5bf9\u540c\u4e00\u6570\u636e\u8fdb\u884c\u8bbf\u95ee\u65f6\uff0c\u6211\u4eec\u79f0\u4e4b\u4e3a\u7a0b\u5e8f\u4e2d\u6709\u6570\u636e\u7ade\u4e89\u3002<\/p>\n<p>\u9664\u4e86\u7ebf\u7a0b\u95f4\u64cd\u4f5c\uff0c\u6570\u636e\u7ade\u4e89\u4e0d\u76f4\u63a5\u5f71\u54cd\u5176\u4ed6\u64cd\u4f5c\u7684\u8bed\u4e49\uff0c\u5982\u8bfb\u53d6\u6570\u7ec4\u7684\u957f\u5ea6\u3001\u68c0\u67e5\u8f6c\u6362\u7684\u6267\u884c\u3001\u865a\u62df\u65b9\u6cd5\u7684\u8c03\u7528\u3002<\/p>\n<p>\u56e0\u6b64\uff0c\u6570\u636e\u7ade\u4e89\u4e0d\u4f1a\u5bfc\u81f4\u9519\u8bef\u7684\u884c\u4e3a\uff0c\u4f8b\u5982\u4e3a\u6570\u7ec4\u8fd4\u56de\u9519\u8bef\u7684\u957f\u5ea6\u3002\u5f53\u4e14\u4ec5\u5f53\u6240\u6709\u8fde\u7eed\u4e00\u81f4\u7684\u64cd\u4f5c\u90fd\u6ca1\u6709\u6570\u636e\u4e89\u7528\u65f6\uff0c\u7a0b\u5e8f\u5c31\u662f\u6b63\u786e\u540c\u6b65\u7684\u3002<\/p>\n<p>\u5982\u679c\u4e00\u4e2a\u7a0b\u5e8f\u662f\u6b63\u786e\u540c\u6b65\u7684\uff0c\u90a3\u4e48\u7a0b\u5e8f\u4e2d\u7684\u6240\u6709\u64cd\u4f5c\u5c31\u4f1a\u8868\u73b0\u51fa\u8fde\u7eed\u4e00\u81f4\u6027\u3002<\/p>\n<p>\u8fd9\u662f\u4e00\u4e2a\u5bf9\u4e8e\u7a0b\u5e8f\u5458\u6765\u8bf4\u5f3a\u6709\u529b\u7684\u4fdd\u8bc1\uff0c\u7a0b\u5e8f\u5458\u4e0d\u9700\u8981\u77e5\u9053\u91cd\u6392\u5e8f\u7684\u539f\u56e0\uff0c\u5c31\u53ef\u4ee5\u786e\u5b9a\u4ed6\u4eec\u7684\u4ee3\u7801\u662f\u5426\u5305\u542b\u6570\u636e\u4e89\u7528\u3002\u56e0\u6b64\uff0c\u4ed6\u4eec\u4e0d\u9700\u8981\u77e5\u9053\u91cd\u6392\u5e8f\u7684\u539f\u56e0\uff0c\u6765\u786e\u5b9a\u4ed6\u4eec\u7684\u4ee3\u7801\u662f\u5426\u662f\u6b63\u786e\u540c\u6b65\u7684\u3002\u4e00\u65e6\u786e\u5b9a\u4e86\u4ee3\u7801\u662f\u6b63\u786e\u540c\u6b65\u7684\uff0c\u7a0b\u5e8f\u5458\u4e5f\u5c31\u4e0d\u9700\u8981\u62c5\u5fc3\u91cd\u6392\u5e8f\u5bf9\u4e8e\u4ee3\u7801\u7684\u5f71\u54cd\u3002<\/p>\n<blockquote><p>\u5176\u5b9e\u5c31\u662f\u6b63\u786e\u540c\u6b65\u7684\u4ee3\u7801\u4e0d\u5b58\u5728\u6570\u636e\u7ade\u4e89\u95ee\u9898\uff0c\u8fd9\u4e2a\u65f6\u5019\u7a0b\u5e8f\u5458\u4e0d\u9700\u8981\u5173\u5fc3\u91cd\u6392\u5e8f\u662f\u5426\u4f1a\u5f71\u54cd\u6211\u4eec\u7684\u4ee3\u7801\uff0c\u6211\u4eec\u7684\u4ee3\u7801\u6267\u884c\u4e00\u5b9a\u4f1a\u8868\u73b0\u51fa\u8fde\u7eed\u4e00\u81f4\u3002<\/p><\/blockquote>\n<p>\u7a0b\u5e8f\u5fc5\u987b\u6b63\u786e\u540c\u6b65\uff0c\u4ee5\u907f\u514d\u5f53\u51fa\u73b0\u91cd\u6392\u5e8f\u65f6\uff0c\u4f1a\u51fa\u73b0\u4e00\u7cfb\u5217\u7684\u5947\u602a\u7684\u884c\u4e3a\u3002\u6b63\u786e\u540c\u6b65\u7684\u4f7f\u7528\uff0c\u4e0d\u80fd\u4fdd\u8bc1\u7a0b\u5e8f\u7684\u5168\u90e8\u884c\u4e3a\u90fd\u662f\u6b63\u786e\u7684\u3002<\/p>\n<p>\u4f46\u662f\uff0c\u5b83\u7684\u4f7f\u7528\u53ef\u4ee5\u8ba9\u7a0b\u5e8f\u5458\u4ee5\u5f88\u7b80\u5355\u7684\u65b9\u5f0f\u5c31\u80fd\u77e5\u9053\u53ef\u80fd\u53d1\u751f\u7684\u884c\u4e3a\u3002\u6b63\u786e\u540c\u6b65\u7684\u7a0b\u5e8f\u8868\u73b0\u51fa\u6765\u7684\u884c\u4e3a\u66f4\u4e0d\u4f1a\u4f9d\u8d56\u4e8e\u53ef\u80fd\u7684\u91cd\u6392\u5e8f\u3002\u6ca1\u6709\u4f7f\u7528\u6b63\u786e\u540c\u6b65\uff0c\u975e\u5e38\u5947\u602a\u3001\u4ee4\u4eba\u7591\u60d1\u3001\u8fdd\u53cd\u76f4\u89c9\u7684\u4efb\u4f55\u884c\u4e3a\u90fd\u662f\u53ef\u80fd\u7684\u3002<\/p>\n<p>\u6211\u4eec\u8bf4\uff0c\u5bf9\u53d8\u91cf v \u7684\u8bfb\u64cd\u4f5c r \u80fd\u770b\u5230\u5bf9 v \u7684\u5199\u64cd\u4f5c w\uff0c\u5982\u679c:<\/p>\n<p>\u8bfb\u64cd\u4f5c r \u4e0d\u662f\u5148\u4e8e w \u53d1\u751f\uff08\u6bd4\u5982\u4e0d\u662f hb(r, w) \uff09\uff0c\u540c\u65f6\u6ca1\u6709\u5199\u64cd\u4f5c w&#8217; \u7a7f\u63d2\u5728 w \u548c r \u4e2d\u95f4\uff08\u5982\u4e0d\u5b58\u5728 hb(w, w&#8217;) \u548c hb(w&#8217;, r)\uff09\u3002\u975e\u6b63\u5f0f\u5730\uff0c\u5982\u679c\u6ca1\u6709 happens-before \u5173\u7cfb\u963b\u6b62\u8bfb\u64cd\u4f5c r\uff0c\u90a3\u4e48\u8bfb\u64cd\u4f5c r \u5c31\u80fd\u770b\u5230\u5199\u64cd\u4f5c w \u7684\u7ed3\u679c\u3002<\/p>\n<h3>17.5. final \u5c5e\u6027\u7684\u8bed\u4e49\uff08final Field Semantics\uff09<\/h3>\n<p>\u6211\u4eec\u7ecf\u5e38\u4f7f\u7528 final\uff0c\u5173\u4e8e\u5b83\u6700\u57fa\u7840\u7684\u77e5\u8bc6\u662f\uff1a<strong>\u7528 final \u4fee\u9970\u7684\u7c7b\u4e0d\u53ef\u4ee5\u88ab\u7ee7\u627f\uff0c\u7528 final \u4fee\u9970\u7684\u65b9\u6cd5\u4e0d\u53ef\u4ee5\u88ab\u8986\u5199\uff0c\u7528 final \u4fee\u9970\u7684\u5c5e\u6027\u4e00\u65e6\u521d\u59cb\u5316\u4ee5\u540e\u4e0d\u53ef\u4ee5\u88ab\u4fee\u6539\u3002<\/strong><\/p>\n<p>\u5f53\u7136\uff0c\u8fd9\u8282\u8bf4\u7684\u4e0d\u662f\u8fd9\u4e9b\uff0c\u8fd9\u91cc\u5c06\u9610\u8ff0 final \u5173\u952e\u5b57\u7684\u6df1\u5c42\u6b21\u542b\u4e49\u3002<\/p>\n<p>\u7528 final \u58f0\u660e\u7684\u5c5e\u6027\u6b63\u5e38\u60c5\u51b5\u4e0b\u521d\u59cb\u5316\u4e00\u6b21\u540e\uff0c\u5c31\u4e0d\u4f1a\u88ab\u6539\u53d8\u3002final \u5c5e\u6027\u7684\u8bed\u4e49\u4e0e\u666e\u901a\u5c5e\u6027\u7684\u8bed\u4e49\u6709\u4e00\u4e9b\u4e0d\u4e00\u6837\u3002\u5c24\u5176\u662f\uff0c\u5bf9\u4e8e final \u5c5e\u6027\u7684\u8bfb\u64cd\u4f5c\uff0ccompilers \u53ef\u4ee5\u81ea\u7531\u5730\u53bb\u9664\u4e0d\u5fc5\u8981\u7684\u540c\u6b65\u3002\u76f8\u5e94\u5730\uff0ccompilers \u53ef\u4ee5\u5c06 final \u5c5e\u6027\u7684\u503c\u7f13\u5b58\u5728\u5bc4\u5b58\u5668\u4e2d\uff0c\u800c\u4e0d\u7528\u50cf\u666e\u901a\u5c5e\u6027\u4e00\u6837\u4ece\u5185\u5b58\u4e2d\u91cd\u65b0\u8bfb\u53d6\u3002<\/p>\n<p><strong>final \u5c5e\u6027\u540c\u65f6\u4e5f\u5141\u8bb8\u7a0b\u5e8f\u5458\u4e0d\u9700\u8981\u4f7f\u7528\u540c\u6b65\u5c31\u53ef\u4ee5\u5b9e\u73b0\u7ebf\u7a0b\u5b89\u5168\u7684\u4e0d\u53ef\u53d8\u5bf9\u8c61\u3002\u4e00\u4e2a\u7ebf\u7a0b\u5b89\u5168\u7684\u4e0d\u53ef\u53d8\u5bf9\u8c61\u5bf9\u4e8e\u6240\u6709\u7ebf\u7a0b\u6765\u8bf4\u90fd\u662f\u4e0d\u53ef\u53d8\u7684\uff0c\u5373\u4f7f\u4f20\u9012\u8fd9\u4e2a\u5bf9\u8c61\u7684\u5f15\u7528\u5b58\u5728\u6570\u636e\u7ade\u4e89\u3002<\/strong><\/p>\n<p>\u8fd9\u53ef\u4ee5\u63d0\u4f9b\u5b89\u5168\u7684\u4fdd\u8bc1\uff0c\u5373\u4f7f\u662f\u9519\u8bef\u7684\u6216\u8005\u6076\u610f\u7684\u5bf9\u4e8e\u8fd9\u4e2a\u4e0d\u53ef\u53d8\u5bf9\u8c61\u7684\u4f7f\u7528\u3002\u5982\u679c\u9700\u8981\u4fdd\u8bc1\u5bf9\u8c61\u4e0d\u53ef\u53d8\uff0c\u9700\u8981\u6b63\u786e\u5730\u4f7f\u7528 final \u5c5e\u6027\u57df\u3002<\/p>\n<p>\u5bf9\u8c61\u53ea\u6709\u5728\u6784\u9020\u65b9\u6cd5\u7ed3\u675f\u4e86\u624d\u88ab\u8ba4\u4e3a\u5b8c\u5168\u521d\u59cb\u5316\u4e86\u3002\u5982\u679c\u4e00\u4e2a\u5bf9\u8c61\u5b8c\u5168\u521d\u59cb\u5316\u4ee5\u540e\uff0c\u4e00\u4e2a\u7ebf\u7a0b\u6301\u6709\u8be5\u5bf9\u8c61\u7684\u5f15\u7528\uff0c\u90a3\u4e48\u8fd9\u4e2a\u7ebf\u7a0b\u4e00\u5b9a\u53ef\u4ee5\u770b\u5230\u6b63\u786e\u521d\u59cb\u5316\u7684 final \u5c5e\u6027\u7684\u503c\u3002<\/p>\n<blockquote><p>\u8fd9\u4e2a\u9690\u542b\u4e86\uff0c\u5982\u679c\u5c5e\u6027\u503c\u4e0d\u662f final \u7684\uff0c\u90a3\u5c31\u4e0d\u80fd\u4fdd\u8bc1\u4e00\u5b9a\u53ef\u4ee5\u770b\u5230\u6b63\u786e\u521d\u59cb\u5316\u7684\u503c\uff0c\u53ef\u80fd\u770b\u5230\u521d\u59cb\u96f6\u503c\u3002<\/p><\/blockquote>\n<p>final \u5c5e\u6027\u7684\u4f7f\u7528\u662f\u975e\u5e38\u7b80\u5355\u7684\uff1a\u5728\u5bf9\u8c61\u7684\u6784\u9020\u65b9\u6cd5\u4e2d\u8bbe\u7f6e final \u5c5e\u6027\uff1b\u540c\u65f6\u5728\u5bf9\u8c61\u521d\u59cb\u5316\u5b8c\u6210\u524d\uff0c\u4e0d\u8981\u5c06\u6b64\u5bf9\u8c61\u7684\u5f15\u7528\u5199\u5165\u5230\u5176\u4ed6\u7ebf\u7a0b\u53ef\u4ee5\u8bbf\u95ee\u5230\u7684\u5730\u65b9\u3002\u5982\u679c\u8fd9\u4e2a\u6761\u4ef6\u6ee1\u8db3\uff0c\u5f53\u5176\u4ed6\u7ebf\u7a0b\u770b\u5230\u8fd9\u4e2a\u5bf9\u8c61\u7684\u65f6\u5019\uff0c\u90a3\u4e2a\u7ebf\u7a0b\u59cb\u7ec8\u53ef\u4ee5\u770b\u5230\u6b63\u786e\u521d\u59cb\u5316\u540e\u7684\u5bf9\u8c61\u7684 final \u5c5e\u6027\u3002<\/p>\n<p>\u8fd9\u91cc\u9762\u8bf4\u5230\u4e86\u4e00\u4e2a\u6b63\u786e\u521d\u59cb\u5316\u7684\u95ee\u9898\uff0c\u770b\u8fc7\u300aJava\u5e76\u53d1\u7f16\u7a0b\u5b9e\u6218\u300b\u7684\u53ef\u80fd\u5bf9\u8fd9\u4e2a\u4f1a\u6709\u5370\u8c61\uff0c\u4e0d\u8981\u5728\u6784\u9020\u65b9\u6cd5\u4e2d\u5c06 this \u53d1\u5e03\u51fa\u53bb\u3002<\/p>\n<p>\u8fd9\u6bb5\u4ee3\u7801\u628afinal\u5c5e\u6027\u548c\u666e\u901a\u5c5e\u6027\u8fdb\u884c\u5bf9\u6bd4\u3002<\/p>\n<pre><code>class FinalFieldExample {\n    final int x;\n    int y;\n    static FinalFieldExample f;\n\n    public FinalFieldExample() {\n        x = 3;\n        y = 4;\n    }\n\n    static void writer() {\n        f = new FinalFieldExample();\n    }\n\n    static void reader() {\n        if (f != null) {\n            int i = f.x;  \/\/ \u7a0b\u5e8f\u4e00\u5b9a\u80fd\u5f97\u5230 3\n            int j = f.y;  \/\/ \u4e5f\u8bb8\u4f1a\u770b\u5230 0\n        }\n    }\n}<\/code><\/pre>\n<p>\u8fd9\u4e2a\u7c7bFinalFieldExample\u6709\u4e00\u4e2a final \u5c5e\u6027 x \u548c\u4e00\u4e2a\u666e\u901a\u5c5e\u6027 y\u3002\u6211\u4eec\u5047\u5b9a\u6709\u4e00\u4e2a\u7ebf\u7a0b\u6267\u884c writer() \u65b9\u6cd5\uff0c\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u518d\u6267\u884c reader() \u65b9\u6cd5\u3002<\/p>\n<p>\u56e0\u4e3a writer() \u65b9\u6cd5\u5728\u5bf9\u8c61\u5b8c\u5168\u6784\u9020\u540e\u5c06\u5f15\u7528\u5199\u5165 f\uff0c\u90a3\u4e48 reader() \u65b9\u6cd5\u5c06\u4e00\u5b9a\u53ef\u4ee5\u770b\u5230\u521d\u59cb\u5316\u540e\u7684 f.x : \u5c06\u8bfb\u5230\u4e00\u4e2a int \u503c 3\u3002\u7136\u800c\uff0c f.y \u4e0d\u662f final \u7684\uff0c\u6240\u4ee5\u7a0b\u5e8f\u4e0d\u80fd\u4fdd\u8bc1\u53ef\u4ee5\u770b\u5230 4\uff0c\u53ef\u80fd\u4f1a\u5f97\u5230 0\u3002<\/p>\n<p>final \u5c5e\u6027\u88ab\u8bbe\u8ba1\u6210\u7528\u6765\u4fdd\u969c\u5f88\u591a\u64cd\u4f5c\u7684\u5b89\u5168\u6027\u3002\u8003\u8651\u4ee5\u4e0b\u4ee3\u7801\uff0c\u7ebf\u7a0b 1 \u6267\u884c\uff1a<\/p>\n<pre><code>Global.s = &quot;\/tmp\/usr&quot;.substring(4);<\/code><\/pre>\n<p>\u540c\u65f6\uff0c\u7ebf\u7a0b 2 \u6267\u884c\uff1a<\/p>\n<pre><code>String myS = Global.s;\nif (myS.equals(&quot;\/tmp&quot;)) System.out.println(myS);<\/code><\/pre>\n<p>String \u5bf9\u8c61\u662f\u4e0d\u53ef\u53d8\u5bf9\u8c61\uff0c\u540c\u65f6 String \u64cd\u4f5c\u4e0d\u9700\u8981\u4f7f\u7528\u540c\u6b65\u3002\u867d\u7136 String \u7684\u5b9e\u73b0\u6ca1\u6709\u4efb\u4f55\u7684\u6570\u636e\u7ade\u4e89\uff0c\u4f46\u662f\u5176\u4ed6\u4f7f\u7528\u5230 String \u5bf9\u8c61\u7684\u4ee3\u7801\u53ef\u80fd\u662f\u5b58\u5728\u6570\u636e\u7ade\u4e89\u7684\uff0c\u5185\u5b58\u6a21\u578b\u6ca1\u6709\u5bf9\u5b58\u5728\u6570\u636e\u7ade\u4e89\u7684\u4ee3\u7801\u63d0\u4f9b\u5b89\u5168\u6027\u4fdd\u8bc1\u3002<\/p>\n<p>\u7279\u522b\u662f\uff0c\u5982\u679c String \u7c7b\u4e2d\u7684\u5c5e\u6027\u4e0d\u662f final \u7684\uff0c\u90a3\u4e48\u6709\u53ef\u80fd\uff08\u867d\u7136\u4e0d\u592a\u53ef\u80fd\uff09\u7ebf\u7a0b 2 \u4f1a\u770b\u5230\u8fd9\u4e2a string \u5bf9\u8c61\u7684 offset \u4e3a\u521d\u59cb\u503c 0\uff0c\u90a3\u4e48\u5c31\u4f1a\u51fa\u73b0 myS.equals(&#8220;\/tmp&#8221;)\u3002<\/p>\n<p>\u4e4b\u540e\u7684\u4e00\u4e2a\u64cd\u4f5c\u53ef\u80fd\u4f1a\u770b\u5230\u8fd9\u4e2a String \u5bf9\u8c61\u7684\u6b63\u786e\u7684 offset \u503c 4\uff0c\u90a3\u4e48\u4f1a\u5f97\u5230 \u201c\/usr\u201d\u3002Java \u4e2d\u7684\u8bb8\u591a\u5b89\u5168\u7279\u6027\u90fd\u4f9d\u8d56\u4e8e String \u5bf9\u8c61\u7684\u4e0d\u53ef\u53d8\u6027\uff0c\u5373\u4f7f\u662f\u6076\u610f\u4ee3\u7801\u5728\u6570\u636e\u7ade\u4e89\u7684\u73af\u5883\u4e2d\u5728\u7ebf\u7a0b\u4e4b\u95f4\u4f20\u9012 String \u5bf9\u8c61\u7684\u5f15\u7528\u3002<\/p>\n<p>\u5927\u5bb6\u770b\u8fd9\u6bb5\u7684\u65f6\u5019\uff0c\u5982\u679c\u8981\u770b\u4ee3\u7801\uff0c\u8bf7\u6ce8\u610f\uff0c\u8fd9\u91cc\u8bf4\u7684\u662f  JDK6 \u53ca\u4ee5\u524d\u7684 String \u7c7b\uff1a<\/p>\n<pre><code>public final class String\n    implements java.io.Serializable, Comparable&lt;String&gt;, CharSequence\n{\n    \/** The value is used for character storage. *\/\n    private final char value[];\n\n    \/** The offset is the first index of the storage that is used. *\/\n    private final int offset;\n\n    \/** The count is the number of characters in the String. *\/\n    private final int count;\n\n    \/** Cache the hash code for the string *\/\n    private int hash; \/\/ Default to 0<\/code><\/pre>\n<blockquote><p>\u56e0\u4e3a\u5230 JDK7 \u548c JDK8 \u7684\u65f6\u5019\uff0c\u4ee3\u7801\u5df2\u7ecf\u53d8\u4e3a\uff1a<\/p><\/blockquote>\n<pre><code>public final class String\n    implements java.io.Serializable, Comparable&lt;String&gt;, CharSequence {\n    \/** The value is used for character storage. *\/\n    private final char value[];\n\n    \/** Cache the hash code for the string *\/\n    private int hash; \/\/ Default to 0\n\n    \/** use serialVersionUID from JDK 1.0.2 for interoperability *\/\n    private static final long serialVersionUID = -6849794470754667710L;<\/code><\/pre>\n<h4>17.5.1. final\u5c5e\u6027\u7684\u8bed\u4e49\uff08Semantics of final Fields\uff09<\/h4>\n<p>\u4ee4 o \u4e3a\u4e00\u4e2a\u5bf9\u8c61\uff0cc \u4e3a o \u7684\u6784\u9020\u65b9\u6cd5\uff0c\u6784\u9020\u65b9\u6cd5\u4e2d\u5bf9 final \u7684\u5c5e\u6027 f \u8fdb\u884c\u5199\u5165\u503c\u3002\u5f53\u6784\u9020\u65b9\u6cd5 c \u9000\u51fa\u7684\u65f6\u5019\uff0c\u4f1a\u5728final \u5c5e\u6027 f \u4e0a\u6267\u884c\u4e00\u4e2a freeze \u64cd\u4f5c\u3002<\/p>\n<p>\u6ce8\u610f\uff0c\u5982\u679c\u4e00\u4e2a\u6784\u9020\u65b9\u6cd5\u8c03\u7528\u4e86\u53e6\u4e00\u4e2a\u6784\u9020\u65b9\u6cd5\uff0c\u5728\u88ab\u8c03\u7528\u7684\u6784\u9020\u65b9\u6cd5\u4e2d\u8bbe\u7f6e final \u5c5e\u6027\uff0c\u90a3\u4e48\u5bf9\u4e8e final \u5c5e\u6027\u7684 freeze \u64cd\u4f5c\u53d1\u751f\u4e8e\u88ab\u8c03\u7528\u7684\u6784\u9020\u65b9\u6cd5\u7ed3\u675f\u7684\u65f6\u5019\u3002<\/p>\n<p>\u5bf9\u4e8e\u6bcf\u4e00\u4e2a\u6267\u884c\uff0c\u8bfb\u64cd\u4f5c\u7684\u884c\u4e3a\u88ab\u5176\u4ed6\u7684\u4e24\u4e2a\u504f\u5e8f\u5f71\u54cd\uff0c\u89e3\u5f15\u7528\u94fe dereferences() \u548c\u5185\u5b58\u94fe mc()\uff0c\u5b83\u4eec\u88ab\u8ba4\u4e3a\u662f\u6267\u884c\u7684\u4e00\u90e8\u5206\u3002\u8fd9\u4e9b\u504f\u5e8f\u5fc5\u987b\u6ee1\u8db3\u4e0b\u9762\u7684\u7ea6\u675f\uff1a<\/p>\n<h4>17.5.2. \u5728\u6784\u9020\u671f\u95f4\u8bfb final \u5c5e\u6027\uff08Reading final Fields During Construction\uff09<\/h4>\n<p>\u5728\u6784\u9020\u5bf9\u8c61\u7684\u7ebf\u7a0b\u4e2d\uff0c\u5bf9\u8be5\u5bf9\u8c61\u7684 final \u5c5e\u6027\u7684\u8bfb\u64cd\u4f5c\uff0c\u9075\u5b88\u6b63\u5e38\u7684 happens-before \u89c4\u5219\u3002\u5982\u679c\u5728\u6784\u9020\u65b9\u6cd5\u5185\uff0c\u8bfb\u67d0\u4e2a final \u5c5e\u6027\u665a\u4e8e\u5bf9\u8fd9\u4e2a\u5c5e\u6027\u7684\u5199\u64cd\u4f5c\uff0c\u90a3\u4e48\u8fd9\u4e2a\u8bfb\u64cd\u4f5c\u53ef\u4ee5\u770b\u5230\u8fd9\u4e2a final \u5c5e\u6027\u5df2\u7ecf\u88ab\u5b9a\u4e49\u7684\u503c\uff0c\u5426\u5219\u5c31\u4f1a\u770b\u5230\u9ed8\u8ba4\u503c\u3002<\/p>\n<h4>17.5.3. final \u5c5e\u6027\u7684\u4fee\u6539\uff08Subsequent Modification of final Fields\uff09<\/h4>\n<p>\u5728\u8bb8\u591a\u573a\u666f\u4e0b\uff0c\u5982\u53cd\u5e8f\u5217\u5316\uff0c\u7cfb\u7edf\u9700\u8981\u5728\u5bf9\u8c61\u6784\u9020\u4e4b\u540e\u6539\u53d8 final \u5c5e\u6027\u7684\u503c\u3002final \u5c5e\u6027\u53ef\u4ee5\u901a\u8fc7\u53cd\u5c04\u548c\u5176\u4ed6\u65b9\u6cd5\u6765\u6539\u53d8\u3002<\/p>\n<p>\u552f\u4e00\u7684\u5177\u6709\u5408\u7406\u8bed\u4e49\u7684\u6a21\u5f0f\u662f\uff1a\u5bf9\u8c61\u88ab\u6784\u9020\u51fa\u6765\uff0c\u7136\u540e\u5bf9\u8c61\u4e2d\u7684 final \u5c5e\u6027\u88ab\u66f4\u65b0\u3002\u5728\u8fd9\u4e2a\u5bf9\u8c61\u7684\u6240\u6709 final \u5c5e\u6027\u66f4\u65b0\u64cd\u4f5c\u5b8c\u6210\u4e4b\u524d\uff0c\u6b64\u5bf9\u8c61\u4e0d\u5e94\u8be5\u5bf9\u5176\u4ed6\u7ebf\u7a0b\u53ef\u89c1\uff0c\u4e5f\u4e0d\u5e94\u8be5\u5bf9 final \u5c5e\u6027\u8fdb\u884c\u8bfb\u64cd\u4f5c\u3002<\/p>\n<p>\u5bf9\u4e8e final \u5c5e\u6027\u7684 freeze \u64cd\u4f5c\u53d1\u751f\u4e8e<strong>\u6784\u9020\u65b9\u6cd5\u7684\u7ed3\u675f\uff0c\u8fd9\u4e2a\u65f6\u5019 final \u5c5e\u6027\u5df2\u7ecf\u88ab\u8bbe\u503c\uff0c\u8fd8\u6709\u901a\u8fc7\u53cd\u5c04\u6216\u5176\u4ed6\u65b9\u5f0f\u5bf9\u4e8e final \u5c5e\u6027\u7684\u66f4\u65b0\u4e4b\u540e\u3002<\/strong><\/p>\n<p>\u5373\u4f7f\u662f\u8fd9\u6837\uff0c\u4f9d\u7136\u5b58\u5728\u51e0\u4e2a\u96be\u70b9\u3002\u5982\u679c\u4e00\u4e2a final \u5c5e\u6027\u5728\u5c5e\u6027\u58f0\u660e\u7684\u65f6\u5019\u521d\u59cb\u5316\u4e3a\u4e00\u4e2a\u5e38\u91cf\u8868\u8fbe\u5f0f\uff0c\u5bf9\u4e8e\u8fd9\u4e2a final \u5c5e\u6027\u503c\u7684\u53d8\u5316\u8fc7\u7a0b\u4e5f\u8bb8\u662f\u4e0d\u53ef\u89c1\u7684\uff0c\u56e0\u4e3a\u5bf9\u4e8e\u8fd9\u4e2a final \u5c5e\u6027\u7684\u4f7f\u7528\u662f\u5728\u7f16\u8bd1\u65f6\u7528\u5e38\u91cf\u8868\u8fbe\u5f0f\u6765\u66ff\u6362\u7684\u3002<\/p>\n<p>\u53e6\u4e00\u4e2a\u95ee\u9898\u662f\uff0c\u8be5\u89c4\u8303\u5141\u8bb8 JVM \u5b9e\u73b0\u5bf9 final \u5c5e\u6027\u8fdb\u884c\u5f3a\u5236\u4f18\u5316\u3002\u5728\u4e00\u4e2a\u7ebf\u7a0b\u5185\uff0c\u5141\u8bb8<strong>\u5bf9\u4e8e final \u5c5e\u6027\u7684\u8bfb\u64cd\u4f5c\u4e0e\u6784\u9020\u65b9\u6cd5\u4e4b\u5916\u7684\u5bf9\u4e8e\u8fd9\u4e2a final \u5c5e\u6027\u7684\u4fee\u6539\u8fdb\u884c\u91cd\u6392\u5e8f\u3002<\/strong><\/p>\n<p><strong>\u5bf9\u4e8e final \u5c5e\u6027\u7684\u5f3a\u5236\u4f18\u5316\uff08Aggressive Optimization of final Fields\uff09<\/strong><\/p>\n<pre><code>class A {\n    final int x;\n    A() {\n        x = 1;\n    }\n\n    int f() {\n        return d(this,this);\n    }\n\n    int d(A a1, A a2) {\n        int i = a1.x;\n        g(a1);\n        int j = a2.x;\n        return j - i;\n    }\n\n    static void g(A a) {\n        \/\/ \u5229\u7528\u53cd\u5c04\u5c06 a.x \u7684\u503c\u4fee\u6539\u4e3a 2\n        \/\/ uses reflection to change a.x to 2\n    }\n}<\/code><\/pre>\n<p>\u5728\u65b9\u6cd5 d \u4e2d\uff0c\u7f16\u8bd1\u5668\u5141\u8bb8\u5bf9 x \u7684\u8bfb\u64cd\u4f5c\u548c\u65b9\u6cd5 g \u8fdb\u884c\u91cd\u6392\u5e8f\uff0c\u8fd9\u6837\u7684\u8bdd\uff0cnew A().f()\u53ef\u80fd\u4f1a\u8fd4\u56de -1, 0, \u6216 1\u3002<\/p>\n<blockquote><p>\u6211\u5728\u6211\u7684 MBP \u4e0a\u8bd5\u4e86\u597d\u591a\u529e\u6cd5\uff0c\u771f\u7684\u6ca1\u6cd5\u91cd\u73b0\u51fa\u6765\uff0c\u4e0d\u8fc7\u5e76\u53d1\u95ee\u9898\u5c31\u662f\u8fd9\u6837\uff0c\u6211\u4eec\u4e0d\u80fd\u91cd\u73b0\u4e0d\u4ee3\u8868\u4e0d\u5b58\u5728\u3002StackOverflow \u4e0a\u6709\u7f51\u53cb\u8bf4\u5728 Sparc \u4e0a\u8fd0\u884c\uff0c\u53ef\u60dc\u6211\u6ca1\u6709 Sparc \u673a\u5668\u3002<\/p><\/blockquote>\n<p>\u4e0b\u6587\u5c06\u8bf4\u5230\u4e00\u4e2a\u6bd4\u8f83\u5c11\u89c1\u7684 final-field-safe context<\/p>\n<p>JVM \u5b9e\u73b0\u53ef\u4ee5\u63d0\u4f9b\u4e00\u79cd\u65b9\u5f0f\u5728 final \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587\uff08final-field-safe context\uff09\u4e2d\u6267\u884c\u4ee3\u7801\u5757\u3002\u5982\u679c\u4e00\u4e2a\u5bf9\u8c61\u662f\u5728 final \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587\u4e2d\u6784\u9020\u51fa\u6765\u7684\uff0c\u90a3\u4e48\u5728\u8fd9\u4e2a final \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587 \u4e2d\u5bf9\u4e8e final \u5c5e\u6027\u7684\u8bfb\u64cd\u4f5c\u4e0d\u4f1a\u548c\u76f8\u5e94\u7684\u5bf9\u4e8e final \u5c5e\u6027\u7684\u4fee\u6539\u8fdb\u884c\u91cd\u6392\u5e8f\u3002<\/p>\n<p>final \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587\u8fd8\u63d0\u4f9b\u4e86\u989d\u5916\u7684\u4fdd\u969c\u3002\u5982\u679c\u4e00\u4e2a\u7ebf\u7a0b\u5df2\u7ecf\u770b\u5230\u4e00\u4e2a\u4e0d\u6b63\u786e\u53d1\u5e03\u7684\u4e00\u4e2a\u5bf9\u8c61\u7684\u5f15\u7528\uff0c\u90a3\u4e48\u6b64\u7ebf\u7a0b\u53ef\u4ee5\u770b\u5230\u4e86 final \u5c5e\u6027\u7684\u9ed8\u8ba4\u503c\uff0c\u7136\u540e\uff0c\u5728 final \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587\u4e2d\u8bfb\u53d6\u8be5\u5bf9\u8c61\u7684\u6b63\u786e\u53d1\u5e03\u7684\u5f15\u7528\uff0c\u8fd9\u53ef\u4ee5\u4fdd\u8bc1\u770b\u5230\u6b63\u786e\u7684 final \u5c5e\u6027\u7684\u503c\u3002\u5728\u5f62\u5f0f\u4e0a\uff0c\u5728final \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587\u4e2d\u6267\u884c\u7684\u4ee3\u7801\u88ab\u8ba4\u4e3a\u662f\u4e00\u4e2a\u72ec\u7acb\u7684\u7ebf\u7a0b\uff08\u4ec5\u7528\u4e8e\u6ee1\u8db3 final \u5c5e\u6027\u7684\u8bed\u4e49\uff09\u3002<\/p>\n<p>\u5728\u5b9e\u73b0\u4e2d\uff0ccompiler \u4e0d\u5e94\u8be5\u5c06\u5bf9 final \u5c5e\u6027\u7684\u8bbf\u95ee\u79fb\u5165\u6216\u79fb\u51fafinal \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587\uff08\u5c3d\u7ba1\u5b83\u53ef\u4ee5\u5728\u8fd9\u4e2a\u6267\u884c\u4e0a\u4e0b\u6587\u7684\u5468\u8fb9\u79fb\u52a8\uff0c\u53ea\u8981\u8fd9\u4e2a\u5bf9\u8c61\u6ca1\u6709\u5728\u8fd9\u4e2a\u4e0a\u4e0b\u6587\u4e2d\u8fdb\u884c\u6784\u9020\uff09\u3002<\/p>\n<p>\u5bf9\u4e8e final \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587\u7684\u4f7f\u7528\uff0c\u4e00\u4e2a\u6070\u5f53\u7684\u5730\u65b9\u662f\u6267\u884c\u5668\u6216\u8005\u7ebf\u7a0b\u6c60\u3002\u5728\u6bcf\u4e2a\u72ec\u7acb\u7684 final \u5c5e\u6027\u5b89\u5168\u4e0a\u4e0b\u6587\u4e2d\u6267\u884c\u6bcf\u4e00\u4e2a Runnable\uff0c\u6267\u884c\u5668\u53ef\u4ee5\u4fdd\u8bc1\u5728\u4e00\u4e2a Runnable \u4e2d\u5bf9\u5bf9\u8c61 o \u7684\u4e0d\u6b63\u786e\u7684\u8bbf\u95ee\u4e0d\u4f1a\u5f71\u54cd\u540c\u4e00\u6267\u884c\u5668\u5185\u7684\u5176\u4ed6 Runnable \u4e2d\u7684 final \u5e26\u6765\u7684\u5b89\u5168\u4fdd\u969c\u3002<\/p>\n<h4>17.5.4. \u5199\u4fdd\u62a4\u5c5e\u6027\uff08Write-Protected Fields\uff09<\/h4>\n<p>\u901a\u5e38\uff0c\u5982\u679c\u4e00\u4e2a\u5c5e\u6027\u662f final \u7684\u548c static \u7684\uff0c\u90a3\u4e48\u8fd9\u4e2a\u5c5e\u6027\u662f\u4e0d\u4f1a\u88ab\u6539\u53d8\u7684\u3002\u4f46\u662f\uff0c System.in, System.out, \u548c System.err \u662f static final \u7684\uff0c\u51fa\u4e8e\u9057\u7559\u7684\u5386\u53f2\u539f\u56e0\uff0c\u5b83\u4eec\u5fc5\u987b\u5141\u8bb8\u88ab System.setIn, System.setOut, \u548c System.setErr \u8fd9\u51e0\u4e2a\u65b9\u6cd5\u6539\u53d8\u3002\u6211\u4eec\u79f0\u8fd9\u4e9b\u5c5e\u6027\u662f\u5199\u4fdd\u62a4\u7684\uff0c\u7528\u4ee5\u533a\u5206\u666e\u901a\u7684 final \u5c5e\u6027\u3002<\/p>\n<pre><code>  public final static InputStream in = null;\n    public final static PrintStream out = null;\n    public final static PrintStream err = null;<\/code><\/pre>\n<p>\u7f16\u8bd1\u5668\u9700\u8981\u5c06\u8fd9\u4e9b\u5c5e\u6027\u4e0e final \u5c5e\u6027\u533a\u522b\u5bf9\u5f85\u3002\u4f8b\u5982\uff0c\u666e\u901a final \u5c5e\u6027\u7684\u8bfb\u64cd\u4f5c\u5bf9\u4e8e\u540c\u6b65\u662f\u201c\u514d\u75ab\u7684\u201d\uff1a\u9501\u6216 volatile \u8bfb\u64cd\u4f5c\u4e2d\u7684\u5185\u5b58\u5c4f\u969c\u5e76\u4e0d\u4f1a\u5f71\u54cd\u5230\u5bf9\u4e8e final \u5c5e\u6027\u7684\u8bfb\u64cd\u4f5c\u8bfb\u5230\u7684\u503c\u3002\u56e0\u4e3a\u5199\u4fdd\u62a4\u5c5e\u6027\u7684\u503c\u662f\u53ef\u4ee5\u88ab\u6539\u53d8\u7684\uff0c\u6240\u4ee5\u540c\u6b65\u4e8b\u4ef6\u5e94\u8be5\u5bf9\u5b83\u4eec\u6709\u5f71\u54cd\u3002\u56e0\u6b64\uff0c\u8bed\u4e49\u89c4\u5b9a\u8fd9\u4e9b\u5c5e\u6027\u88ab\u5f53\u505a\u666e\u901a\u5c5e\u6027\uff0c\u4e0d\u80fd\u88ab\u7528\u6237\u7684\u4ee3\u7801\u6539\u53d8\uff0c\u9664\u975e\u662f System\u7c7b\u4e2d\u7684\u4ee3\u7801\u3002<\/p>\n<h3>17.6. \u5b57\u5206\u88c2\uff08Word Tearing\uff09<\/h3>\n<p>\u5b9e\u73b0 Java \u865a\u62df\u673a\u9700\u8981\u8003\u8651\u7684\u4e00\u4ef6\u4e8b\u60c5\u662f\uff0c\u6bcf\u4e2a\u5bf9\u8c61\u5c5e\u6027\u4ee5\u53ca\u6570\u7ec4\u5143\u7d20\u4e4b\u95f4\u662f\u72ec\u7acb\u7684\uff0c\u66f4\u65b0\u4e00\u4e2a\u5c5e\u6027\u6216\u5143\u7d20\u4e0d\u80fd\u5f71\u54cd\u5176\u4ed6\u5c5e\u6027\u6216\u5143\u7d20\u7684\u8bfb\u53d6\u4e0e\u66f4\u65b0\u3002\u5c24\u5176\u662f\uff0c\u4e24\u4e2a\u7ebf\u7a0b\u5728\u5206\u522b\u66f4\u65b0 byte \u6570\u7ec4\u76f8\u90bb\u7684\u5143\u7d20\u65f6\uff0c\u4e0d\u80fd\u4e92\u76f8\u5f71\u54cd\u4e0e\u5e72\u6270\uff0c\u4e14\u4e0d\u9700\u8981\u540c\u6b65\u6765\u4fdd\u8bc1\u8fde\u7eed\u4e00\u81f4\u6027\u3002<\/p>\n<p>\u4e00\u4e9b\u5904\u7406\u5668\u4e0d\u63d0\u4f9b\u5199\u5165\u5355\u4e2a\u5b57\u8282\u7684\u80fd\u529b\u3002\u901a\u8fc7\u7b80\u5355\u5730\u8bfb\u53d6\u6574\u4e2a\u5b57\uff0c\u66f4\u65b0\u76f8\u5e94\u7684\u5b57\u8282\uff0c\u7136\u540e\u5c06\u6574\u4e2a\u5b57\u5199\u5165\u5185\u5b58\uff0c\u7528\u8fd9\u79cd\u65b9\u5f0f\u5728\u8fd9\u79cd\u5904\u7406\u5668\u4e0a\u5b9e\u73b0\u5b57\u8282\u6570\u7ec4\u66f4\u65b0\u662f\u975e\u6cd5\u7684\u3002\u8fd9\u4e2a\u95ee\u9898\u6709\u65f6\u88ab\u79f0\u4e3a\u5b57\u5206\u88c2\uff08word tearing\uff09\uff0c\u5728\u8fd9\u79cd\u4e0d\u80fd\u5355\u72ec\u66f4\u65b0\u5355\u4e2a\u5b57\u8282\u7684\u5904\u7406\u5668\u4e0a\uff0c\u5c06\u9700\u8981\u5bfb\u6c42\u5176\u4ed6\u7684\u65b9\u6cd5\u3002<\/p>\n<blockquote><p>\u8bf7\u6ce8\u610f\uff0c\u5bf9\u4e8e\u5927\u90e8\u5206\u5904\u7406\u5668\u6765\u8bf4\uff0c\u90fd\u6ca1\u6709\u8fd9\u4e2a\u95ee\u9898<\/p><\/blockquote>\n<p><strong>Example 17.6-1. Detection of Word Tearing<\/strong><\/p>\n<p>\u4ee5\u4e0b\u7a0b\u5e8f\u7528\u4e8e\u6d4b\u8bd5\u662f\u5426\u5b58\u5728\u5b57\u5206\u88c2\uff1a<\/p>\n<pre><code>public class WordTearing extends Thread {\n    static final int LENGTH = 8;\n    static final int ITERS = 1000000;\n    static byte[] counts = new byte[LENGTH];\n    static Thread[] threads = new Thread[LENGTH];\n\n    final int id;\n\n    WordTearing(int i) {\n        id = i;\n    }\n\n    public void run() {\n        byte v = 0;\n        for (int i = 0; i &lt; ITERS; i++) {\n            byte v2 = counts[id];\n            if (v != v2) {\n                System.err.println(&quot;Word-Tearing found: &quot; +\n                        &quot;counts[&quot; + id + &quot;] = &quot; + v2 +\n                        &quot;, should be &quot; + v);\n                return;\n            }\n            v++;\n            counts[id] = v;\n        }\n        System.out.println(&quot;done&quot;);\n    }\n\n    public static void main(String[] args) {\n        for (int i = 0; i &lt; LENGTH; ++i)\n            (threads[i] = new WordTearing(i)).start();\n    }\n}<\/code><\/pre>\n<p>\u8fd9\u8868\u660e\u5199\u5165\u5b57\u8282\u65f6\u4e0d\u5f97\u8986\u5199\u76f8\u90bb\u7684\u5b57\u8282\u3002<\/p>\n<h3>17.7. double \u548c long \u7684\u975e\u539f\u5b50\u5904\u7406 \uff08Non-Atomic Treatment of double and long\uff09<\/h3>\n<p>\u5728Java\u5185\u5b58\u6a21\u578b\u4e2d\uff0c\u5bf9\u4e8e non-volatile \u7684 long \u6216 double \u503c\u7684\u5199\u5165\u662f\u901a\u8fc7\u4e24\u4e2a\u5355\u72ec\u7684\u5199\u64cd\u4f5c\u5b8c\u6210\u7684\uff1along \u548c double \u662f 64 \u4f4d\u7684\uff0c\u88ab\u5206\u4e3a\u4e24\u4e2a 32 \u4f4d\u6765\u8fdb\u884c\u5199\u5165\u3002\u90a3\u4e48\u53ef\u80fd\u5c31\u4f1a\u5bfc\u81f4\u4e00\u4e2a\u7ebf\u7a0b\u770b\u5230\u4e86\u67d0\u4e2a\u64cd\u4f5c\u7684\u4f4e 32 \u4f4d\u7684\u5199\u5165\u548c\u53e6\u4e00\u4e2a\u64cd\u4f5c\u7684\u9ad8 32 \u4f4d\u7684\u5199\u5165\u3002<\/p>\n<p>\u5199\u5165\u6216\u8005\u8bfb\u53d6 volatile \u7684 long \u548c double \u503c\u662f\u539f\u5b50\u7684\u3002<\/p>\n<p>\u5199\u5165\u548c\u8bfb\u53d6\u5bf9\u8c61\u5f15\u7528\u4e00\u5b9a\u662f\u539f\u5b50\u7684\uff0c\u4e0d\u7ba1\u5177\u4f53\u5b9e\u73b0\u662f32\u4f4d\u8fd8\u662f64\u4f4d\u3002<\/p>\n<p>\u5c06\u4e00\u4e2a 64 \u4f4d\u7684 long \u6216 double \u503c\u7684\u5199\u5165\u5206\u4e3a\u76f8\u90bb\u7684\u4e24\u4e2a 32 \u4f4d\u7684\u5199\u5165\u5bf9\u4e8e JVM \u7684\u5b9e\u73b0\u6765\u8bf4\u662f\u5f88\u65b9\u4fbf\u7684\u3002\u4e3a\u4e86\u6027\u80fd\u4e0a\u7684\u8003\u8651\uff0cJVM \u7684\u5b9e\u73b0\u662f\u53ef\u4ee5\u51b3\u5b9a\u91c7\u7528\u539f\u5b50\u5199\u5165\u8fd8\u662f\u5206\u4e3a\u4e24\u4e2a\u90e8\u5206\u5199\u5165\u7684\u3002<\/p>\n<p>\u5982\u679c\u53ef\u80fd\u7684\u8bdd\uff0c\u6211\u4eec\u9f13\u52b1 JVM \u7684\u5b9e\u73b0\u907f\u5f00\u5c06 64 \u4f4d\u503c\u7684\u5199\u5165\u5206\u62c6\u6210\u4e24\u4e2a\u64cd\u4f5c\u3002\u6211\u4eec\u4e5f\u5e0c\u671b\u7a0b\u5e8f\u5458\u5c06\u5171\u4eab\u7684 64 \u4f4d\u503c\u64cd\u4f5c\u8bbe\u7f6e\u4e3a volatile \u6216\u8005\u4f7f\u7528\u6b63\u786e\u7684\u540c\u6b65\uff0c\u8fd9\u6837\u53ef\u4ee5\u63d0\u4f9b\u66f4\u597d\u7684\u517c\u5bb9\u6027\u3002<\/p>\n<blockquote><p>\u76ee\u524d\u6765\u770b\uff0c64 \u4f4d\u865a\u62df\u673a\u5bf9\u4e8e long \u548c double \u7684\u5199\u5165\u90fd\u662f\u539f\u5b50\u7684\uff0c\u6ca1\u5fc5\u8981\u52a0 volatile \u6765\u4fdd\u8bc1\u539f\u5b50\u6027\u3002<\/p><\/blockquote>\n<p>\u6765\u6e90\uff1a<a href=\"https:\/\/link.segmentfault.com\/?enc=V%2Bs7CnDGzxMICpv0jlvPWA%3D%3D.0LkUmT1AaIhtJDMy3HH5imDtEWfd2gd3zij%2B%2FSsHyGm2PidhShr%2BgisHAz7Tirqb\" rel=\"nofollow\">https:\/\/javadoop.com\/post\/Thr&#8230;<\/a>\/<\/p>\n<p>\u53c2\u8003\uff1a\/<br \/><a href=\"https:\/\/link.segmentfault.com\/?enc=gt1a86j6dPwAZf9zahMt2g%3D%3D.KOhbqnusMVIKYDhEIjXNFY%2BkPekVrNm6lfWsgY0XTUU8gP4pyE7JBgP02gbz11hi\" rel=\"nofollow\">https:\/\/docs.oracle.com\/javas&#8230;<\/a>\/<br \/><a href=\"https:\/\/link.segmentfault.com\/?enc=eQE%2BTIQ%2Bm5pN1gm2Eccz7A%3D%3D.JmsbHzo8rmw9n2flJNLT9eS%2Bbi3ucpR1PBLI6XTSYzgDmpbmROxn521N3%2F7nWcypIUe5kKPxHEe9ZZChMsMOoA%3D%3D\" rel=\"nofollow\">http:\/\/www.cs.umd.edu\/~pugh\/j&#8230;<\/a>\/<br \/><a href=\"https:\/\/link.segmentfault.com\/?enc=FJWIMvEVdzoVIhLOrdk%2FRQ%3D%3D.cRbsURIbbij9SIty9IFrEh3s45jZQlnaPTL4a7f76ImgW4b5BMptn8wMyQnXlNNK\" rel=\"nofollow\">http:\/\/gee.cs.oswego.edu\/dl\/j&#8230;<\/a><\/p>\n<p><strong>\u8fd1\u671f\u70ed\u6587\u63a8\u8350\uff1a<\/strong><\/p>\n<p>1.<a href=\"https:\/\/link.segmentfault.com\/?enc=oLdbvClAnzt5IyQ8CSgFnA%3D%3D.uDIvzNLNQD14FGbOrFp3oHr0ks%2BqAPqrv8vQSOpnnKQ%3D\" rel=\"nofollow\">1,000+ \u9053 Java\u9762\u8bd5\u9898\u53ca\u7b54\u6848\u6574\u7406(2022\u6700\u65b0\u7248)<\/a><\/p>\n<p>2.<a href=\"https:\/\/link.segmentfault.com\/?enc=8jnU4A%2BUbfy2pAR1MPWLmQ%3D%3D.U%2F9NurVKLPVQfVUzOSnD6DWqD7i%2F9%2FQ6nvklKrBBCrMhhBPallp5jDv9oTFgioT2Aw3fP%2FOmp30fiVBHVzBv5aI6nL1gTtC6A2WRa7O53VM%3D\" rel=\"nofollow\">\u52b2\u7206\uff01Java \u534f\u7a0b\u8981\u6765\u4e86\u3002\u3002\u3002<\/a><\/p>\n<p>3.<a href=\"https:\/\/link.segmentfault.com\/?enc=o0ai562Mbud%2BKYSxILTI%2Bg%3D%3D.7vS8cEjGR%2F07fjNwSP0EZ3lBnTmWR5YEo5mTtBaUsX22hjVrnlxWlDRnGwPP1L76\" rel=\"nofollow\">Spring Boot 2.x \u6559\u7a0b\uff0c\u592a\u5168\u4e86\uff01<\/a><\/p>\n<p>4.<a href=\"https:\/\/link.segmentfault.com\/?enc=WCknduuc8ei2xG02k1NZWw%3D%3D.Ppild7xyN8pqlJd33DgDusRJsE2THJK%2FMrv%2FBoya5YjvqXUVdMW4o1fhAkKE8rBsppZEx1Q4BN15tY5fM%2FxYYr4hkocM33Vl3w470G1FwtY%3D\" rel=\"nofollow\">\u522b\u518d\u5199\u6ee1\u5c4f\u7684\u7206\u7206\u7206\u70b8\u7c7b\u4e86\uff0c\u8bd5\u8bd5\u88c5\u9970\u5668\u6a21\u5f0f\uff0c\u8fd9\u624d\u662f\u4f18\u96c5\u7684\u65b9\u5f0f\uff01\uff01<\/a><\/p>\n<p>5.<a href=\"https:\/\/link.segmentfault.com\/?enc=xjTTTXFi%2F9HWvzgDV%2FcjvQ%3D%3D.H8Rkvb2eJdsrtWgduzwzHVkyhusTvAnV4vOcTL1bjuVhGvumOlaFwXcJs%2FcjrwwdIlIe9WDWTLJEVhe2TFPEbVyJCD%2B6ulleD0RnGkDgRgNBjrTKA%2FeQb2g9qUgyJjcQ\" rel=\"nofollow\">\u300aJava\u5f00\u53d1\u624b\u518c\uff08\u5d69\u5c71\u7248\uff09\u300b\u6700\u65b0\u53d1\u5e03\uff0c\u901f\u901f\u4e0b\u8f7d\uff01<\/a><\/p>\n<p>\u89c9\u5f97\u4e0d\u9519\uff0c\u522b\u5fd8\u4e86\u968f\u624b\u70b9\u8d5e+\u8f6c\u53d1\u54e6\uff01<\/p>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000042282545\">https:\/\/segmentfault.com\/a\/1190000042282545<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728 java \u5e76\u53d1\u7f16\u7a0b\u4e2d\uff0c\u7ebf\u7a0b\u548c\u9501\u6c38\u8fdc\u662f\u6700\u91cd\u8981\u7684\u6982\u5ff5\u3002\u8bed\u8a00\u89c4\u8303\u867d\u7136\u662f\u89c4\u8303\u63cf\u8ff0\uff0c\u4f46\u662f\u5176\u4e2d\u4e5f\u6709\u975e\u5e38\u591a\u7684\u77e5\u8bc6\u548c\u6700\u4f73\u5b9e [&hellip;]<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[],"tags":[],"class_list":["post-10006141","post","type-post","status-publish","format-standard","hentry"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006141","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"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10006141"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006141\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10006141"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10006141"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10006141"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}