jstack
jstack用于生成java虚拟机当前时刻的线程快照。线程快照是当前java虚拟机内每一条线程正在执行的方法堆栈的集合，生成线程快照的主要目的是定位线程出现长时间停顿的原因，如线程间死锁、死循环、请求外部资源导致的长时间等待等。 线程出现停顿的时候通过jstack来查看各个线程的调用堆栈，就可以知道没有响应的线程到底在后台做什么事情，或者等待什么资源。 如果java程序崩溃生成core文件，jstack工具可以用来获得core文件的java stack和native stack的信息，从而可以轻松地知道java程序是如何崩溃和在程序何处发生问题。另外，jstack工具还可以附属到正在运行的java程序中，看到当时运行的java程序的java stack和native stack的信息, 如果现在运行的java程序呈现hung的状态，jstack是非常有用的。【线程分析】
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[root@localhost bin]# jstack -help
Usage: jstack [-l] <pid>
(to connect to running process)
jstack -F [-m] [-l] <pid>
(to connect to a hung process)
jstack [-m] [-l] <executable> <core>
(to connect to a core file)
jstack [-m] [-l] [server_id@]<remote server IP or hostname>
(to connect to a remote debug server)
Options: -F to force a thread dump. Use when jstack <pid> does not respond (process is hung)
-m to print both java and native frames (mixed mode)
-l long listing. Prints additional information about locks
-h or -help to print this help message
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参数
-F：当正常输出请求不被响应时，强制输出线程栈堆。
-l：除线程栈堆外，显示关于锁的附加信息。
-m：如果调用本地方法的话，可以显示c/c++的栈堆
示例
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[root@localhost bin]# jstack -m 24971 | more
Attaching to process ID 24971, please wait...Debugger attached successfully.Server compiler detected.JVM version is 24.79-b02Deadlock Detection:No deadlocks found.----------------- 24972 -----------------0x00007fe07d2cd69d __GI___poll + 0x2d0x00007fe070dc80a7 Java_java_net_PlainSocketImpl_socketAccept + 0x1e70x00007fe0745a3d98 * java.net.PlainSocketImpl.socketAccept(java.net.SocketImpl) bci:0 (Interpreted frame)0x00007fe074597058 * java.net.AbstractPlainSocketImpl.accept(java.net.SocketImpl) bci:7 line:398 (Interpreted frame)0x00007fe074597058 * java.net.ServerSocket.implAccept(java.net.Socket) bci:60 line:530 (Interpreted frame)0x00007fe074597058 * java.net.ServerSocket.accept() bci:48 line:498 (Interpreted frame)0x00007fe074597233 * org.apache.catalina.core.StandardServer.await() bci:180 line:470 (Interpreted frame)0x00007fe074597706 * org.apache.catalina.startup.Catalina.await() bci:4 line:782 (Interpreted frame)0x00007fe074597058 * org.apache.catalina.startup.Catalina.start() bci:209 line:728 (Interpreted frame)0x00007fe0745914e7 <StubRoutines>0x00007fe07c967e95 _ZN9JavaCalls11call_helperEP9JavaValueP12methodHandleP17JavaCallArgumentsP6Thread + 0x3650x00007fe07c9668f8 _ZN9JavaCalls4callEP9JavaValue12methodHandleP17JavaCallArgumentsP6Thread + 0x280x00007fe07cbfdeef _ZN10Reflection6invokeE19instanceKlassHandle12methodHandle6Handleb14objArrayHandle9BasicTypeS3_bP6Thread + 0x47f0x00007fe07cbfeca0 _ZN10Reflection13invoke_methodEP7oopDesc6Handle14objArrayHandleP6Thread + 0x160 |