--- order: 4 --- # 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： 1. 访问系统某些功能时反应很慢，但其他功能正常。 2. 访问系统所有页面都很慢，但网络是正常的。 3. 怀疑系统内部有死锁。 4. 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”{#threadstack-system} 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](./images/2020-05-29-14-36-42.png) ## 方法2.windows上ctrl+break {#threadstack-windows} 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 {#threadstack-kill3} 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：** 1. 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` ```sh 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 ``` 2. 执行kill -3 + java进程号，如：`kill -3 8913104` 3. 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： ```sh 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:** 1. 获取进程id和kill命令和上面的操作一致。 2. tomcat的输出信息在catalina.out文件中。 3. 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 {#threadstack-jstack} ```sh 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 {#threadstack-analyse} 1. 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](https://www.ibm.com/developerworks/mydeveloperworks/groups/service/html/communityview?communityUuid=2245aa39-fa5c-4475-b891-14c205f7333c)，点击 [此处](ftp://public.dhe.ibm.com/software/websphere/appserv/support/tools/jca/jca445.jar)下载jca441.jar。 2. 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。