Arthas 是Alibaba开源的Java诊断工具，深受开发者喜爱。

当你遇到以下类似问题而束手无策时，Arthas可以帮助你解决：

这个类从哪个 jar 包加载的？为什么会报各种类相关的 Exception？我改的代码为什么没有执行到？难道是我没 commit？分支搞错了？遇到问题无法在线上 debug，难道只能通过加日志再重新发布吗？线上遇到某个用户的数据处理有问题，但线上同样无法 debug，线下无法重现！是否有一个全局视角来查看系统的运行状况？有什么办法可以监控到JVM的实时运行状态？

Arthas支持JDK 6+，支持Linux/Mac/Windows，采用命令行交互模式，同时提供丰富的 Tab 自动补全功能，进一步方便进行问题的定位和诊断。

在线教程(推荐)基础教程：;id=arthas-basics进阶教程：;id=arthas-advanced快速开始

使用arthas-boot(推荐)

下载arthas-boot.jar，然后用java -jar的方式启动：

wget  -jar arthas-boot.jar

打印帮助信息：

java -jar arthas-boot.jar -h

使用as.sh

Arthas 支持在 Linux/Unix/Mac 等平台上一键安装，请复制以下内容，并粘贴到命令行中，敲 回车 执行即可：

curl -L  | sh

上述命令会下载启动脚本文件 as.sh 到当前目录，你可以放在任何地方或将其加入到 $PATH 中。

直接在shell下面执行./as.sh，就会进入交互界面。

也可以执行./as.sh -h来获取更多参数信息。

文档

Gitee文档镜像：

Arthas 基础命令help——查看命令帮助信息cls——清空当前屏幕区域session——查看当前会话的信息reset——重置增强类，将被 Arthas 增强过的类全部还原，Arthas 服务端关闭时会重置所有增强过的类version——输出当前目标 Java 进程所加载的 Arthas 版本号history——打印命令历史quit——退出当前 Arthas 客户端，其他 Arthas 客户端不受影响shutdown——关闭 Arthas 服务端，所有 Arthas 客户端全部退出keymap——Arthas快捷键列表及自定义快捷键案例展示

Dashboard

Thread

一目了然的了解系统的状态，哪些线程比较占cpu？他们到底在做什么？

$ thread -n 3"as-command-execute-daemon" Id=29 cpuUsage=75% RUNNABLE at sun.management.ThreadImpl.dumpThreads0(Native Method) at sun.management.ThreadImpl.getThreadInfo(ThreadImpl.java:440) at com.taobao.arthas.core.command.monitor200.ThreadCommand$1.action(ThreadCommand.java:58) at com.taobao.arthas.core.command.handler.AbstractCommandHandler.execute(AbstractCommandHandler.java:238) at com.taobao.arthas.core.command.handler.DefaultCommandHandler.handleCommand(DefaultCommandHandler.java:67) at com.taobao.arthas.core.server.ArthasServer$4.run(ArthasServer.java:276) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:745) Number of locked synchronizers = 1 - java.util.concurrent.ThreadPoolExecutor$Worker@6cd0b6f8"as-session-expire-daemon" Id=25 cpuUsage=24% TIMED_WAITING at java.lang.Thread.sleep(Native Method) at com.taobao.arthas.core.server.DefaultSessionManager$2.run(DefaultSessionManager.java:85)"Reference Handler" Id=2 cpuUsage=0% WAITING on java.lang.ref.Reference$Lock@69ba0f27 at java.lang.Object.wait(Native Method) - waiting on java.lang.ref.Reference$Lock@69ba0f27 at java.lang.Object.wait(Object.java:503) at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)

jad

对类进行反编译:

$ jad javax.servlet.ServletClassLoader:+-java.net.URLClassLoader@6108b2d7 +-sun.misc.Launcher$AppClassLoader@18b4aac2 +-sun.misc.Launcher$ExtClassLoader@1ddf84b8Location:/Users/xxx/work/test/lib/servlet-api.jar/* * Decompiled with CFR 0_122. */package javax.servlet;import java.io.IOException;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;public interface Servlet { public void init(ServletConfig var1) throws ServletException; public ServletConfig getServletConfig(); public void service(ServletRequest var1, ServletResponse var2) throws ServletException, IOException; public String getServletInfo(); public void destroy();}

mc

Memory Compiler/内存编译器，编译.java文件生成.class。

mc /tmp/Test.java

redefine

加载外部的.class文件，redefine jvm已加载的类。

redefine /tmp/Test.classredefine -c 327a647b /tmp/Test.class /tmp/Test\$Inner.class

sc

查找JVM中已经加载的类

$ sc -d org.springframework.web.context.support.XmlWebApplicationContext class-info org.springframework.web.context.support.XmlWebApplicationContext code-source /Users/xxx/work/test/WEB-INF/lib/spring-web-3.2.11.RELEASE.jar name org.springframework.web.context.support.XmlWebApplicationContext isInterface false isAnnotation false isEnum false isAnonymousClass false isArray false isLocalClass false isMemberClass false isPrimitive false isSynthetic false simple-name XmlWebApplicationContext modifier public annotation interfaces super-class +-org.springframework.web.context.support.AbstractRefreshableWebApplicationContext +-org.springframework.context.support.AbstractRefreshableConfigApplicationContext +-org.springframework.context.support.AbstractRefreshableApplicationContext +-org.springframework.context.support.AbstractApplicationContext +-org.springframework.core.io.DefaultResourceLoader +-java.lang.Object class-loader +-org.apache.catalina.loader.ParallelWebappClassLoader +-java.net.URLClassLoader@6108b2d7 +-sun.misc.Launcher$AppClassLoader@18b4aac2 +-sun.misc.Launcher$ExtClassLoader@1ddf84b8 classLoaderHash 25131501

stack

查看方法 test.arthas.TestStack#doGet 的调用堆栈：

$ stack test.arthas.TestStack doGetPress Ctrl+C to abort.Affect(class-cnt:1 , method-cnt:1) cost in 286 ms.ts=2018-09-18 10:11:45;thread_name=http-bio-8080-exec-10;id=d9;is_daemon=true;priority=5;TCCL=org.apache.catalina.loader.ParallelWebappClassLoader@25131501 @test.arthas.TestStack.doGet() at javax.servlet.http.HttpServlet.service(HttpServlet.java:624) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110) ... at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:451) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1121) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)

Trace

观察方法执行的时候哪个子调用比较慢:

Watch

观察方法 test.arthas.TestWatch#doGet 执行的入参，仅当方法抛出异常时才输出。

$ watch test.arthas.TestWatch doGet {params[0], throwExp} -ePress Ctrl+C to abort.Affect(class-cnt:1 , method-cnt:1) cost in 65 ms.ts=2018-09-18 10:26:28;result=@ArrayList[ @RequestFacade[org.apache.catalina.connector.RequestFacade@79f922b2], @NullPointerException[java.lang.NullPointerException],]

Monitor

监控某个特殊方法的调用统计数据，包括总调用次数，平均rt，成功率等信息，每隔5秒输出一次。

$ monitor -c 5 org.apache.dubbo.demo.provider.DemoServiceImpl sayHelloPress Ctrl+C to abort.Affect(class-cnt:1 , method-cnt:1) cost in 109 ms. timestamp class method total success fail avg-rt(ms) fail-rate---------------------------------------------------------------------------------------------------------------------------- 2018-09-20 09:45:32 org.apache.dubbo.demo.provider.DemoServiceImpl sayHello 5 5 0 0.67 0.00% timestamp class method total success fail avg-rt(ms) fail-rate---------------------------------------------------------------------------------------------------------------------------- 2018-09-20 09:45:37 org.apache.dubbo.demo.provider.DemoServiceImpl sayHello 5 5 0 1.00 0.00% timestamp class method total success fail avg-rt(ms) fail-rate---------------------------------------------------------------------------------------------------------------------------- 2018-09-20 09:45:42 org.apache.dubbo.demo.provider.DemoServiceImpl sayHello 5 5 0 0.43 

Time Tunnel(tt)

记录方法调用信息，支持事后查看方法调用的参数，返回值，抛出的异常等信息，仿佛穿越时空隧道回到调用现场一般。

$ tt -t org.apache.dubbo.demo.provider.DemoServiceImpl sayHelloPress Ctrl+C to abort.Affect(class-cnt:1 , method-cnt:1) cost in 75 ms. INDEX TIMESTAMP COST(ms) IS-RET IS-EXP OBJECT CLASS METHOD------------------------------------------------------------------------------------------------------------------------------------- 1000 2018-09-20 09:54:10 1.971195 true false 0x55965cca DemoServiceImpl sayHello 1001 2018-09-20 09:54:11 0.215685 true false 0x55965cca DemoServiceImpl sayHello 1002 2018-09-20 09:54:12 0.236303 true false 0x55965cca DemoServiceImpl sayHello 1003 2018-09-20 09:54:13 0.159598 true false 0x55965cca DemoServiceImpl sayHello 1004 2018-09-20 09:54:14 0.201982 true false 0x55965cca DemoServiceImpl sayHello 1005 2018-09-20 09:54:15 0.214205 true false 0x55965cca DemoServiceImpl sayHello 1006 2018-09-20 09:54:16 0.241863 true false 0x55965cca DemoServiceImpl sayHello 1007 2018-09-20 09:54:17 0.305747 true false 0x55965cca DemoServiceImpl sayHello 1008 2018-09-20 09:54:18 0.18468 true false 0x55965cca DemoServiceImpl sayHello

Classloader

了解当前系统中有多少类加载器，以及每个加载器加载的类数量，帮助您判断是否有类加载器泄露。

$ classloader name numberOfInstances loadedCountTotal BootstrapClassLoader 1 3346 com.taobao.arthas.agent.ArthasClassloader 1 1262 java.net.URLClassLoader 2 1033 org.apache.catalina.loader.ParallelWebappClassLoader 1 628 sun.reflect.DelegatingClassLoader 166 166 sun.misc.Launcher$AppClassLoader 1 31 com.alibaba.fastjson.util.ASMClassLoader 6 15 sun.misc.Launcher$ExtClassLoader 1 7 org.jvnet.hk2.internal.DelegatingClassLoader 2 2 sun.reflect.misc.MethodUtil 1 1

Web Console

项目地址