JVM調優命令-jstack

時間 2019-11-21

標籤 jvm 命令 jstack 欄目 Java 简体版

原文原文鏈接

jstack

jstack用於生成java虛擬機當前時刻的線程快照。線程快照是當前java虛擬機內每一條線程正在執行的方法堆棧的集合，生成線程快照的主要目的是定位線程出現長時間停頓的緣由，如線程間死鎖、死循環、請求外部資源致使的長時間等待等。線程出現停頓的時候經過jstack來查看各個線程的調用堆棧，就能夠知道沒有響應的線程到底在後臺作什麼事情，或者等待什麼資源。若是java程序崩潰生成core文件，jstack工具能夠用來得到core文件的java stack和native stack的信息，從而能夠輕鬆地知道java程序是如何崩潰和在程序何處發生問題。另外，jstack工具還能夠附屬到正在運行的java程序中，看到當時運行的java程序的java stack和native stack的信息, 若是如今運行的java程序呈現hung的狀態，jstack是很是有用的。【線程分析】

 
         [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

參數java

-F：當正常輸出請求不被響應時，強制輸出線程棧堆。c++

-l：除線程棧堆外，顯示關於鎖的附加信息。apache

-m：若是調用本地方法的話，能夠顯示c/c++的棧堆bash

示例socket

 
         [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-b02 
        
         Deadlock Detection: 
        
         No deadlocks found. 
        
         ----------------- 24972 ----------------- 
        
         0x00007fe07d2cd69d  __GI___poll + 0x2d 
        
         0x00007fe070dc80a7  Java_java_net_PlainSocketImpl_socketAccept + 0x1e7 
        
         0x00007fe0745a3d98  * 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 + 0x365 
        
         0x00007fe07c9668f8  _ZN9JavaCalls4callEP9JavaValue12methodHandleP17JavaCallArgumentsP6Thread + 0x28 
        
         0x00007fe07cbfdeef  _ZN10Reflection6invokeE19instanceKlassHandle12methodHandle6Handleb14objArrayHandle9BasicTypeS3_bP6Thread + 0x 
        
         47f 
        
         0x00007fe07cbfeca0  _ZN10Reflection13invoke_methodEP7oopDesc6Handle14objArrayHandleP6Thread + 0x160