# 如何获取服务器JVM运行堆栈

当系统出现下列情况之一时，可能需要系统管理员能获取到服务器的java虚拟机的运行堆栈，来帮助研发人员排查问题：

访问系统某些功能时反应很慢，但其他功能正常。
访问系统所有页面都很慢，但网络是正常的。
怀疑系统内部有死锁。
为了更准确的定位问题，可以多获取几次堆栈信息，每次获取间隔1～3秒时间。

# 方法1.通过系统功能“线程堆栈”

访问系统设置下的线程堆栈，效果如下图所示（当系统出现故障、卡顿、网络不畅时可能无法进入系统设置，此时需要使用下面的其他方法）：

线程堆栈

# 方法2.windows上ctrl+break

在windows的cmd控制台上启动tomcat、jetty时，可以通过按下简单ctrl+break来获取JVM堆栈，堆栈会直接输出到标准输出上

# 方法3.linux、unix上kill -3命令

使用kill -3 + java进程号，可以通知java进程输出其线程堆栈，sun的jdk会直接将堆栈输出到标准输出上，ibm的jdk（websphere）会生成javacore文件。

linux/unix+websphere获取java线程堆栈信息的具体操作步骤如下：

通过命令ps -ef | grep java来获取相应的java进程号，例如下面的命令可以显示websphere的server1进程的进程号是8913104

was@ZHSIMAVAR1:/home/was#ps -ef | grep java | grep server1
 was  8913104        1   2   May 26      -  9:46 /home/was/IBM/WebSphere/AppServer/java/bin/java -Declipse.security -Dwas.status.socket=32891 -Dosgi.install.area=/home/was/IBM/WebSphere/AppServer -Dosgi.configuration.area=/home/was/IBM/WebSphere/AppServer/profiles/AppSrv01/servers/server1/configuration -Djava.awt.headless=true -Dosgi.framework.extensions=com.ibm.cds,com.ibm.ws.eclipse.adaptors -Xshareclasses:name=webspherev80_%g,groupAccess,nonFatal -Xbootclasspath/p:/home/was/IBM/WebSphere/AppServer/java/jre/lib/ibmorb.jar -classpath /home/was/IBM/WebSphere/AppServer/profiles/AppSrv01/properties:/home/was/IBM/WebSphere/AppServer/properties:/home/was/IBM/WebSphere/AppServer/lib/startup.jar:/home/was/IBM/WebSphere/AppServer/lib/bootstrap.jar:/home/was/IBM/WebSphere/AppServer/lib/jsf-nls.jar:/home/was/IBM/WebSphere/AppServer/lib/lmproxy.jar:/home/was/IBM/WebSphere/AppServer/lib/urlprotocols.jar:/home/was/IBM/WebSphere/AppServer/deploytool/itp/batchboot.jar:/home/was/IBM/WebSphere/AppServer/deploytool/itp/batch2.jar:/home/was/IBM/WebSphere/AppServer/java/lib/tools.jar -Dibm.websphere.internalClassAccessMode=allow -Xms1024m -Xmx4096m -Xcompressedrefs -Xscmaxaot4M -Xscmx60M -Dws.ext.dirs=/home/was/IBM/WebSphere/AppServer/java/lib:/home/was/IBM/WebSphere/AppServer/profiles/AppSrv01/classes:/home/was/IBM/WebSphere/AppServer/classes:/home/was/IBM/WebSphere/AppServer/lib:/home/was/IBM/WebSphere/AppServer/installedChannels:/home/was/IBM/WebSphere/AppServer/lib/ext:/home/was/IBM/WebSphere/AppServer/web/help:/home/was/IBM/WebSphere/AppServer/deploytool/itp/plugins/com.ibm.etools.ejbdeploy/runtime -Dderby.system.home=/home/was/IBM/WebSphere/AppServer/derby -Dcom.ibm.itp.location=/home/was/IBM/WebSphere/AppServer/bin -Djava.util.logging.configureByServer=true -Duser.install.root=/home/was/IBM/WebSphere/AppServer/profiles/AppSrv01 -Djava.ext.dirs=/home/was/IBM/WebSphere/AppServer/tivoli/tam:/home/was/IBM/WebSphere/AppServer/java/jre/lib/ext -Djavax.management.builder.initial=com.ibm.ws.management.PlatformMBeanServerBuilder -Dpython.cachedir=/home/was/IBM/WebSphere/AppServer/profiles/AppSrv01/temp/cachedir -Dwas.install.root=/home/was/IBM/WebSphere/AppServer -Djava.util.logging.manager=com.ibm.ws.bootstrap.WsLogManager -Dserver.root=/home/was/IBM/WebSphere/AppServer/profiles/AppSrv01 -Dcom.ibm.security.jgss.debug=off -Dcom.ibm.security.krb5.Krb5Debug=off -Dfile.encoding=UTF-8 -Djava.library.path=/home/was/IBM/WebSphere/AppServer/lib/native/aix/ppc_64/:/ima/vg1/IBM/WebSphere/AppServer/java/jre/lib/ppc64/default:/ima/vg1/IBM/WebSphere/AppServer/java/jre/lib/ppc64:/ima/vg1/IBM/WebSphere/AppServer/java/jre/lib/ppc64/j9vm:/ima/vg1/IBM/WebSphere/AppServer/java/jre/../lib/ppc64:/home/was/IBM/WebSphere/AppServer/bin:/usr/lib:/ima/vg1/IBM/cognos/c10/bin64/: -Djava.endorsed.dirs=/home/was/IBM/WebSphere/AppServer/endorsed_apis:/home/was/IBM/WebSphere/AppServer/java/jre/lib/endorsed:/home/was/IBM/WebSphere/AppServer/endorsed_apis:/home/was/IBM/WebSphere/AppServer/java/jre/lib/endorsed -Djava.security.auth.login.config=/home/was/IBM/WebSphere/AppServer/profiles/AppSrv01/properties/wsjaas.conf -Djava.security.policy=/home/was/IBM/WebSphere/AppServer/profiles/AppSrv01/properties/server.policy com.ibm.wsspi.bootstrap.WSPreLauncher -nosplash -application com.ibm.ws.bootstrap.WSLauncher com.ibm.ws.runtime.WsServer /home/was/IBM/WebSphere/AppServer/profiles/AppSrv01/config ZHSIMAVAR1Node01Cell ZHSIMAVAR1Node01 server1

执行kill -3 + java进程号，如：kill -3 8913104

javacore文件会自动生成在在websphere的profile目录下，例如javacore.20130527.173545.8913104.0001.txt，文件名中有时间信息：

was@ZHSIMAVAR1:/home/was#cd /home/was/IBM/WebSphere/AppServer/profiles/AppSrv01
was@ZHSIMAVAR1:/home/was/IBM/WebSphere/AppServer/profiles/AppSrv01#ls -l
total 46864
drwxr-xr-x    2 was      was            4096 May 27 17:12 WORKDIR_IS_UNDEFINED
drwxr-xr-x    3 was      was           12288 Apr 10 17:38 bin
drwxr-xr-x    9 was      was             256 Apr 10 17:51 config
drwxr-xr-x    6 was      was             256 Apr 10 17:44 configuration
drwxr-xr-x   10 was      was             256 May 16 21:35 consolepreferences
drwxr-xr-x    3 was      was            4096 Apr 10 17:38 etc
drwxr-xr-x    2 was      was            4096 Apr 10 17:37 firststeps
drwxr-xr-x    2 was      was             256 Apr 10 17:37 installableApps
drwxr-xr-x    3 was      was             256 Apr 10 17:38 installedApps
drwxr-xr-x    2 was      was             256 Apr 10 17:37 installedConnectors
drwxr-xr-x    3 was      was             256 Apr 10 17:51 installedFilters
-rw-r--r--    1 was      was         6490778 Apr 19 14:24 javacore.20130419.142441.8585306.0001.txt
-rw-r--r--    1 was      was         6507262 Apr 19 14:24 javacore.20130419.142446.8585306.0002.txt
-rw-r--r--    1 was      was         6488667 Apr 19 14:24 javacore.20130419.142448.8585306.0003.txt
-rw-r--r--    1 was      was         4456135 May 27 17:35 javacore.20130527.173545.8913104.0001.txt
drwxr-xr-x    5 was      was             256 Apr 10 17:59 logs
drwxr-xr-x    4 was      was            4096 Apr 10 17:38 properties
drwxr-xr-x    3 was      was             256 Apr 10 17:38 servers
drwxr-xr-x    5 was      was            4096 Apr 10 17:51 temp
drwxr-xr-x    3 was      was             256 Apr 10 17:51 tranlog
drwxr-xr-x    8 was      was            4096 May 26 10:01 workspace
drwxr-xr-x   12 was      was            4096 May 26 10:01 wstemp

linux/unix+tomcat/weblogic 获取java线程堆栈信息的具体操作步骤如下:

获取进程id和kill命令和上面的操作一致。
tomcat的输出信息在catalina.out文件中。
weblogic在weblogic的标准输出文件中，如果是使用nohup启动的weblogic那么可能在nohup.out文件中。

# 方法4. jstack -l pid 命令

jstack -l 12353 > ./jvm-stacktrace.log

jstack 为java自带的命令，可以在java安装目录bin下找到，12353 为当前java对应的进程号。导出线程堆栈，建议间隔几秒钟连续导出3次，要捕捉到当时计算的场景。

# 线程内容分析

通过ibm提供的javacore分析工具jca441.jar打开javacore文件，参考ibm官方说明 (opens new window)，点击此处下载jca441.jar。
使用命令java -jar ~/Downloads/jca441.jar 运行，然后点击工具栏上面的Open Thread Dumps按钮，选择javacore文件即可。

如何查看操作系统资源使用情况

OOM（OutOfMemoryError）故障排查

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