## Arthas ![arthas](site/src/site/sphinx/arthas.png) `Arthas` is an Java Diagnostic tool open sourced by Alibaba. Arthas can help developer trouble-shooting production issues for Java applications without modifying your code or restating your server. ### Background In production system, sometimes the networks is unreachable from local development environment. If you encounter some issues in production system, it is impossible to use IDE to debug the application remotely. More importantly, debugging in production is unacceptable, because it will suspend all the threads, which leads to business unavailability. Some may think of reproducing the same issue on the test/staging environment, however, some tricky issue either can hardly be reproduced on a different environment, or even disappeared once restarted. Thinking of adding some logs to your code? You have to go through test, staging, and then on to production. Time is money! That is a lot inefficient! Besides, the issue may not be reproducible once restart your JVM, as described above. Arthas is born to solve these issues. You can trouble-shoot your production issue on-the-fly. No JVM restart, no additional code changes. Arthas works as an observer, which will never suspend your existing threads. ### Key features * check whether a class is loaded? And whether is class loaded from? (Useful for trouble-shooting jar file conflicts) * decompile a class to ensure the code is running as expected. * view classloader statistics, e.g. how may classloaders are there? how many class is loaded per classloader? What is the classloader hierarchy? Is there possible classloader leaks? * view the method invocation details, e.g. method parameter, return object, thrown exception, and etc. * check the stack trace of specified method invocation. This is useful when you would like to know who is calling your method? * trace the method invocation to find slow sub-invocations. * monitoring your system metrics, thread states and cpu usage, gc statistics, and etc. * command line interactive mode, with auto completed feature enabled. * telnet and websocket support, which enables both local and remote diagnostics with command line and browsers. ### Quick start #### Linux/Unix/Mac Install Arthas: ``` curl -L https://alibaba.github.io/arthas/install.sh | sh ``` Start Arthas: ``` ./as.sh ``` #### Windows 1. Click [here](http://search.maven.org/classic/#search%7Cga%7C1%7Cg%3A%22com.taobao.arthas%22%20AND%20a%3A%22arthas-packaging%22) to Download the latest binary releases. 2. Unzip the file. 3. Go to the bin directory 4. run the following command `as.bat $PID` ### Documentation English version is on the way, if you would like to contribute, please leave a message [here](https://github.com/alibaba/arthas/issues/51) * [User manual](https://alibaba.github.io/arthas/) * [Installation](https://alibaba.github.io/arthas/install-detail.html) * [Quick start](https://alibaba.github.io/arthas/quick-start.html) * [Advanced usage](https://alibaba.github.io/arthas/advanced-use.html) * [Questions and answers](https://github.com/alibaba/arthas/labels/question-answered) * [How to contribute](https://github.com/alibaba/arthas/blob/master/CONTRIBUTING.md) ### Feature Showcase #### Dashboard * https://alibaba.github.io/arthas/dashboard ![dashboard](site/src/site/sphinx/_static/dashboard.png) #### Thread See who is eating your cpu (ranked by top cpu usage) and what is going on there in one glance: ``` $ 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 Decompile your class with one shot: ```java $ jad javax.servlet.Servlet ClassLoader: +-java.net.URLClassLoader@6108b2d7 +-sun.misc.Launcher$AppClassLoader@18b4aac2 +-sun.misc.Launcher$ExtClassLoader@1ddf84b8 Location: /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(); } ``` #### sc Search any loaded class with detailed infomation. ``` $ 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 View the call stack of `test.arthas.TestStack#doGet`: ``` $ stack test.arthas.TestStack doGet Press 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 See who is slowing down your method invocation with trace command: ![trace](site/src/site/sphinx/_static/trace.png) #### Watch Watch the first parameter and thrown exception of `test.arthas.TestWatch#doGet` only if it throws exception. ``` $ watch test.arthas.TestWatch doGet {params[0], throwExp} -e Press 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], ] ``` #### Classloader ``` $ 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 * https://alibaba.github.io/arthas/web-console ![web console](site/src/site/sphinx/_static/web-console-local.png)