Java\u70ed\u66f4\u65b0<\/strong><\/span><\/div>\n
\u5728\u6301\u7eed\u4ea4\u4ed8\u7684\u65f6\u4ee3\uff0c\u91cd\u65b0\u90e8\u7f72\u4e00\u4e2a\u65b0\u7684\u7248\u672c\u53ea\u9700\u8981\u70b9\u51fb\u4e00\u4e0b\u6309\u94ae\u3002\u4f46\u5728\u6709\u7684\u60c5\u51b5\u4e0b\uff0c\u91cd\u65b0\u90e8\u7f72\u8fc7\u7a0b\u53ef\u80fd\u6bd4\u8f83\u590d\u6742\uff0c\u505c\u673a\u662f\u4e0d\u88ab\u5141\u8bb8\u7684\u3002\u6240\u4ee5JVM\u63d0\u4f9b\u4e86\u53e6\u5916\u4e00\u79cd\u9009\u62e9\uff1a\u5728\u4e0d\u91cd\u542f\u5e94\u7528\u7684\u524d\u63d0\u4e0b\u8fdb\u884c\u5c0f\u5e45\u6539\u52a8\uff0c\u53c8\u79f0\u70ed\u66f4\u65b0\u3002<\/p>\n
$\"\"$ <\/p>\n
\u5bf9\u4e8e\u67d0\u4e9b\u5927\u578b\u7684\u5e94\u7528\u6765\u8bf4\uff0c\u6bcf\u6b21\u7684\u91cd\u542f\u90fd\u9700\u8981\u82b1\u8d39\u5927\u91cf\u7684\u65f6\u95f4\u6210\u672c\uff0c\u6240\u4ee5\uff0c\u5982\u679c\u80fd\u5728\u4e0d\u91cd\u542f\u865a\u62df\u673a\u7684\u60c5\u51b5\u4e0b\u66f4\u65b0\u4e00\u4e2a\u7c7b\uff0c\u5728\u67d0\u4e9b\u4e1a\u52a1\u573a\u666f\u4e0b\u53d8\u5f97\u5341\u5206\u91cd\u8981\u3002\u6bd4\u5982\u5f88\u591a\u811a\u672c\u8bed\u8a00\u5c31\u652f\u6301\u70ed\u66ff\u6362\uff0c\u4f8b\u5982\u670d\u52a1\u5668\u7aefPHP\uff0c\u53ea\u8981\u66ff\u6362\u4e86PHP\u6e90\u6587\u4ef6\uff0c\u8fd9\u79cd\u6539\u52a8\u5c31\u4f1a\u7acb\u5373\u751f\u6548\uff0c\u65e0\u9700\u91cd\u542f\u670d\u52a1\u5668\u3002<\/p>\n
\u5728Java\u5f00\u53d1\u9886\u57df\uff0c\u70ed\u66f4\u65b0\u4e00\u76f4\u662f\u4e00\u4e2a\u96be\u4ee5\u89e3\u51b3\u7684\u95ee\u9898\uff0c\u76ee\u524d\u7684Java\u865a\u62df\u673a\u53ea\u80fd\u5b9e\u73b0\u65b9\u6cd5\u7ea7\u522b\u7684\u70ed\u66f4\u65b0\uff0c\u5bf9\u4e8e\u6574\u4e2a\u7c7b\u7684\u7ed3\u6784\u4fee\u6539\uff0c\u4ecd\u7136\u9700\u8981\u91cd\u542f\u865a\u62df\u673a\u3002<\/p>\n
\u70ed\u66f4\u65b0\u7684\u65b9\u6cd5<\/strong><\/span><\/div>\n
Java\u70ed\u66f4\u65b0\u4e00\u76f4\u4e0d\u65ad\u5730\u6539\u8fdb\u3002<\/p>\n
1.4\u5f00\u59cbJPDA\u5f15\u5165\u4e86hotSwap\u673a\u5236(JPDA Enhancements)\uff0c\u5b9e\u73b0\u4e86debug\u65f6\u7684method body\u7684\u52a8\u6001\u6027\u3002<\/p>\n
1.5\u5f00\u59cb\u901a\u8fc7JVMTI\u5b9e\u73b0\u7684java.lang.instrument(Java Platform SE 8)\u7684premain\u65b9\u5f0f\uff0c\u5b9e\u73b0\u4e86agent\u65b9\u5f0f\u7684\u52a8\u6001\u6027(JVM\u542f\u52a8\u65f6\u6307\u5b9aagent)\u3002<\/p>\n
1.6\u589e\u52a0\u4e86agentmain\u65b9\u5f0f\uff0c\u5b9e\u73b0\u4e86\u8fd0\u884c\u65f6\u52a8\u6001\u6027(\u901a\u8fc7The Attach API \u7ed1\u5b9a\u5230\u5177\u4f53VM)\u3002\u5176\u57fa\u672c\u5b9e\u73b0\u662f\u901a\u8fc7JVMTI\u7684retransformClass\/redefineClass\u8fdb\u884c\u51fd\u6570\u4f53\u7ea7\u522b\u7684\u5b57\u8282\u7801\u66f4\u65b0\uff0cASM\u3001CGLib\u4e4b\u7c7b\u57fa\u672c\u90fd\u662f\u56f4\u7ed5\u8fd9\u4e9b\u5728\u505a\u52a8\u6001\u6027\u3002<\/p>\n
1.\u5b9a\u4e49\u4e0d\u540c\u7684classloader<\/p>\n
\u5728\u4e86\u89e3JVM ClassLoader\u4e4b\u540e(\u53ef\u4ee5\u70b9\u51fb\u67e5\u770b\u300aJava\u7c7b\u52a0\u8f7d\u53ca\u5bf9\u8c61\u521b\u5efa\u8fc7\u7a0b\u8be6\u89e3\u300b)\uff0c\u53ef\u4ee5\u901a\u8fc7\u5b9a\u4e49\u4e0d\u540c\u7684ClassLoader\uff0c\u76d1\u542c\u6587\u4ef6\u53d8\u5316\u540e\uff0c\u901a\u8fc7\u65b0\u7684ClassLoader\u52a0\u8f7d\u65b0\u6587\u4ef6\uff0c\u7136\u540e\u505a\u597d\u76f8\u5e94\u7684\u72b6\u6001\u6062\u590d\uff0c\u5bf9\u65e7ClassLoader\u8fdb\u884c\u5378\u8f7d\u7b49\u52a8\u4f5c\u3002(\u65e7classloader\u53ca\u52a0\u8f7d\u7684class\u7c7b\u5728\u6ca1\u6709\u5b9e\u4f8b\u5f15\u7528\u7684\u60c5\u51b5\u4e0b,full gc\u65f6\u4f1a\u88ab\u56de\u6536\u6389)<\/p>\n
Tomcat\u7684\u52a8\u6001\u90e8\u7f72\u5c31\u662f\u76d1\u542cwar\u53d8\u5316\uff0c\u7136\u540e\u8c03\u7528StandardContext.reload()\uff0c\u7528\u65b0\u7684WebContextClassLoader\u5b9e\u4f8b\u6765\u52a0\u8f7dwar\uff0c\u7136\u540e\u521d\u59cb\u5316servlet\u6765\u5b9e\u73b0\u3002\u7c7b\u4f3c\u7684\u5b9e\u73b0\u8fd8\u6709OSGi\u7b49\u3002<\/p>\n
\u8fd9\u79cd\u70ed\u66f4\u65b0\u7684\u6d41\u7a0b\u5982\u4e0b\uff1a
\n $\"\"$ <\/p>\n
\u91cd\u65b0\u52a0\u8f7d\u7c7b\u7684\u8fc7\u7a0b<\/p>\n
2.agentmain<\/p>\n
\u7b14\u8005\u7684\u9879\u76ee\u76ee\u524d\u91c7\u7528\u7684\u8fd9\u79cd\u5f62\u5f0f\uff0c\u867d\u7136\u7b14\u8005\u9020\u8fc7\u597d\u591a\u8f6e\u5b50\uff0c\u4f46\u7b14\u8005\u66f4\u770b\u597dArthas\u8fd9\u6837\u7684\u5f00\u6e90\u4ea7\u54c1\u3002\u3002\u3002<\/p>\n
agentmain\u70ed\u66f4\u65b0\u7684\u539f\u7406<\/strong><\/span><\/div>\n
\u4e3a\u4e86\u5b9e\u73b0Java\u8fdb\u7a0bA\u4e0e\u8fdb\u7a0bB\u4e4b\u95f4\u7684\u672c\u5730\u901a\u4fe1\uff0c\u70ed\u66f4\u65b0\u7684JVM\u8fdb\u7a0b\u4f7f\u7528VirutalMachine.attach(pid)\u6765\u8fde\u63a5\u9700\u8981\u70ed\u66f4\u65b0\u7684JVM\u8fdb\u7a0b\uff0c\u7136\u540e\u4f7f\u7528virtualMachine.loadAgent\u52a0\u8f7d\u81ea\u5b9a\u4e49\u7684agent(\u7b14\u8005\u67e5\u770b\u4e86Arthas\u6e90\u7801\uff0c\u539f\u7406\u4e5f\u5927\u81f4\u76f8\u540c)\u3002\u8fd9\u4e2a\u901a\u4fe1\u901a\u9053\u6210\u529f\u5efa\u7acb\u4e4b\u540e\uff0c\u90a3\u4e48\u8fdb\u7a0bA\u5c31\u80fd\u901a\u77e5\u8fdb\u7a0bB\u53bb\u6267\u884c\u67d0\u4e9b\u64cd\u4f5c\uff0c\u4ece\u800c\u8fbe\u5230\u76d1\u63a7\u8fdb\u7a0bB\u6216\u8005\u63a7\u5236\u8fdb\u7a0bB\u7684\u67d0\u4e9b\u884c\u4e3a\u7684\u76ee\u7684\u3002\u5982jstack\u3001jmap\u7b49JDK\u81ea\u5e26\u7684\u5de5\u5177\uff0c\u57fa\u672c\u90fd\u662f\u901a\u8fc7Attach\u673a\u5236\u53bb\u8fbe\u6210\u5404\u81ea\u60f3\u8981\u7684\u76ee\u7684\u7684\u3002<\/p>\n
JVM\u542f\u52a8\u7684\u65f6\u5019\uff0c\u5728JVM\u5185\u90e8\u542f\u52a8\u4e86\u4e00\u4e2a\u76d1\u542c\u7ebf\u7a0b\uff0c\u8fd9\u4e2a\u7ebf\u7a0b\u7684\u540d\u5b57\u53eb\u201cSignal Dispatcher\u201d\uff0c\u8be5\u7ebf\u7a0b\u7684\u4f5c\u7528\u662f\uff0c\u76d1\u542c\u5e76\u5904\u7406OS\u7684\u4fe1\u53f7\u3002<\/p>\n
\u4fe1\u53f7\u662f\u4e00\u79cd\u8fdb\u7a0b\u901a\u4fe1\u3002\u5982\u5e73\u5e38\u6211\u4eec\u7528\u7684\u6700\u591a\u7684\u5c31\u662f kill -9 ${pid}\u6765\u6740\u6b7b\u67d0\u4e2a\u8fdb\u7a0b\uff0ckill\u8fdb\u7a0b\u901a\u8fc7\u5411${pid}\u7684\u8fdb\u7a0b\u53d1\u9001\u4e00\u4e2a\u7f16\u53f7\u4e3a\u201c9\u201d\u53f7\u7684\u4fe1\u53f7\uff0c\u6765\u901a\u77e5\u7cfb\u7edf\u5f3a\u5236\u7ed3\u675f${pid}\u7684\u751f\u547d\u5468\u671f\u3002)<\/p>\n
\u81f3\u4e8eattach\u5b9e\u73b0\uff0c\u5728Linux\u4e0b\u65f6\u4f7f\u7528\u6587\u4ef6Socket\u8fdb\u884c\u8fdb\u7a0b\u901a\u4fe1(\u5bf9\u540c\u4e00\u4e2a\u6587\u4ef6\u8fdb\u884c\u8bfb\u5199\u64cd\u4f5c\uff0c\u4ee5\u8fbe\u5230\u4fe1\u606f\u7684\u4ea4\u4e92\u548c\u5171\u4eab)\u3002<\/p>\n
\u66f4\u8be6\u7ec6\u7684\u539f\u7406\uff0cJVM\u5927\u795e\u5bd2\u6cc9\u5b50\u6709\u7bc7\u6587\u7ae0\u300aJVM\u6e90\u7801\u5206\u6790\u4e4bjavaagent\u539f\u7406\u5b8c\u5168\u89e3\u8bfb\u300b\uff0c\u5982\u70b9\u51fb\u65e0\u6cd5\u8df3\u8f6c\uff0c\u8bf7\u67e5\u770b\u7b14\u8005CSDN\u535a\u5ba2\u539f\u6587\u6765\u70b9\u51fb\u8d85\u94fe\u63a5\u3002<\/p>\n
3.Arthas<\/p>\n
Arthas\u662f\u963f\u91cc\u5df4\u5df4\u6700\u8fd1\u5f00\u6e90\u51fa\u6765\u7684\u4e00\u4e2a\u9488\u5bf9java\u7684\u5de5\u5177\uff0c\u4e3b\u8981\u662f\u9488\u5bf9java\u7684\u95ee\u9898\u8fdb\u884c\u8bca\u65ad\u3002<\/p>\n
\u8df3\u8f6c\u5b98\u7f51\u5730\u5740<\/strong><\/span><\/div>\n
\u8fd9\u4e2a\u5de5\u5177\u53ef\u4ee5\u534f\u52a9\u5b8c\u6210\u4e0b\u9762\u8fd9\u4e9b\u4e8b\u60c5(\u8f6c\u81ea\u5b98\u7f51)\uff1a<\/p>\n
\u8fd9\u4e2a\u7c7b\u662f\u4ece\u54ea\u4e2ajar\u5305\u52a0\u8f7d\u800c\u6765\u7684?<\/p>\n
\u4e3a\u4ec0\u4e48\u4f1a\u62a5\u5404\u79cd\u7c7b\u76f8\u5173\u7684Exception?<\/p>\n
\u7ebf\u4e0a\u9047\u5230\u95ee\u9898\u65e0\u6cd5debug\u597d\u86cb\u75bc\uff0c\u96be\u9053\u53ea\u80fd\u53cd\u590d\u901a\u8fc7\u589e\u52a0System.out\u6216\u901a\u8fc7\u52a0\u65e5\u5fd7\u518d\u91cd\u65b0\u53d1\u5e03\u5417?<\/p>\n
\u7ebf\u4e0a\u7684\u4ee3\u7801\u4e3a\u4ec0\u4e48\u6ca1\u6709\u6267\u884c\u5230\u8fd9\u91cc?\u662f\u7531\u4e8e\u4ee3\u7801\u6ca1\u6709commit?\u8fd8\u662f\u641e\u9519\u4e86\u5206\u652f?<\/p>\n
\u7ebf\u4e0a\u9047\u5230\u67d0\u4e2a\u7528\u6237\u7684\u6570\u636e\u5904\u7406\u6709\u95ee\u9898\uff0c\u4f46\u7ebf\u4e0a\u540c\u6837\u65e0\u6cd5 debug\uff0c\u7ebf\u4e0b\u65e0\u6cd5\u91cd\u73b0\u3002<\/p>\n
\u662f\u5426\u6709\u4e00\u4e2a\u5168\u5c40\u89c6\u89d2\u6765\u67e5\u770b\u7cfb\u7edf\u7684\u8fd0\u884c\u72b6\u51b5?<\/p>\n
\u6709\u4ec0\u4e48\u529e\u6cd5\u53ef\u4ee5\u76d1\u63a7\u5230JVM\u7684\u5b9e\u65f6\u8fd0\u884c\u72b6\u6001?<\/p>\n
Arthas\u91c7\u7528\u547d\u4ee4\u884c\u4ea4\u4e92\u6a21\u5f0f\uff0c\u540c\u65f6\u63d0\u4f9b\u4e30\u5bcc\u7684Tab\u81ea\u52a8\u8865\u5168\u529f\u80fd\uff0c\u8fdb\u4e00\u6b65\u65b9\u4fbf\u8fdb\u884c\u95ee\u9898\u7684\u5b9a\u4f4d\u548c\u8bca\u65ad\u3002<\/p>\n
Arthas\u63d0\u4f9b\u5728\u7ebf\u6559\u7a0b\uff0c\u76f8\u6bd4\u4e00\u822c\u7684\u5f00\u6e90\u4ea7\u54c1\uff0c\u4e0a\u624b\u771f\u7684\u5f88\u8d5e\u3002<\/p>\n
arthas\u5b9e\u73b0\u70ed\u66f4\u65b0<\/strong><\/span><\/div>\n
\u4f7f\u7528Arthas\u4e09\u4e2a\u547d\u4ee4\u5c31\u53ef\u4ee5\u641e\u5b9a\u70ed\u66f4\u65b0<\/p>\n
\r\njad --source-only com.example.demo.arthas.user.UserController > \/tmp\/UserController.java \r\nmc \/tmp\/UserController.java -d \/tmp \r\nredefine \/tmp\/com\/example\/demo\/arthas\/user\/UserController.class \r\n<\/pre>\n
jad\u547d\u4ee4\u53cd\u7f16\u8bd1\uff0c\u7136\u540e\u53ef\u4ee5\u7528\u5176\u5b83\u7f16\u8bd1\u5668\uff0c\u6bd4\u5982vim\u6765\u4fee\u6539\u6e90\u7801<\/p>\n
mc\u547d\u4ee4\u6765\u5185\u5b58\u7f16\u8bd1\u4fee\u6539\u8fc7\u7684\u4ee3\u7801<\/p>\n
\u7528redefine\u547d\u4ee4\u52a0\u8f7d\u65b0\u7684\u5b57\u8282\u7801<\/p>\n
JVM\u70ed\u66f4\u65b0\u7684\u5c40\u9650<\/strong><\/span><\/div>\n
\u57fa\u4e8eAttach\u673a\u5236\u5b9e\u73b0\u7684\u70ed\u66f4\u65b0\uff0c\u66f4\u65b0\u7c7b\u9700\u8981\u4e0e\u539f\u6765\u7684\u7c7b\u5728\u5305\u540d\uff0c\u7c7b\u540d\uff0c\u4fee\u9970\u7b26\u4e0a\u5b8c\u5168\u4e00\u81f4\uff0c\u5426\u5219\u5728classRedefine\u8fc7\u7a0b\u4e2d\u4f1a\u4ea7\u751fclassname don't match \u7684\u5f02\u5e38\u3002<\/p>\n
\u4f8b\u5982\u663e\u793a\u8fd9\u6837\u7684\u62a5\u9519\uff1aredefineClasses exception class redefinition failed: attempted to delete a method.<\/p>\n
\u5177\u4f53\u6765\u8bf4\uff0cJVM\u70ed\u66f4\u65b0\u5c40\u9650\u603b\u7ed3\uff1a<\/p>\n
\u51fd\u6570\u53c2\u6570\u683c\u5f0f\u4e0d\u80fd\u4fee\u6539\uff0c\u53ea\u80fd\u4fee\u6539\u51fd\u6570\u5185\u90e8\u7684\u903b\u8f91<\/p>\n
\u4e0d\u80fd\u589e\u52a0\u7c7b\u7684\u51fd\u6570\u6216\u53d8\u91cf<\/p>\n
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