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Arthas is a Java Diagnostic tool open sourced by Alibaba.
Arthas allows developers to troubleshoot production issues for Java applications without modifying code or restarting servers.
Often times, the production system network is inaccessible from the local development environment. If issues are encountered in production systems, it is impossible to use IDEs to debug the application remotely. More importantly, debugging in production environment is unacceptable, as it will suspend all the threads, resulting in the suspension of business services.
Developers could always try to reproduce the same issue on the test/staging environment. However, this is tricky as some issues cannot be reproduced easily on a different environment, or even disappear once restarted.
And if you're thinking of adding some logs to your code to help troubleshoot the issue, you will have to go through the following lifecycle; test, staging, and then to production. Time is money! This approach is inefficient! Besides, the issue may not be reproducible once the JVM is restarted, as described above.
Arthas was built to solve these issues. A developer can troubleshoot your production issues on-the-fly. No JVM restart, no additional code changes. Arthas works as an observer, which will never suspend your existing threads.
- Check whether a class is loaded, or where the class is being loaded. (Useful for troubleshooting jar file conflicts)
- Decompile a class to ensure the code is running as expected.
- View classloader statistics, e.g. the number of classloaders, the number of classes loaded per classloader, the classloader hierarchy, possible classloader leaks, etc.
- 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 a developers wants to know the caller of the said method.
- Trace the method invocation to find slow sub-invocations.
- Monitor method invocation statistics, e.g. qps, rt, success rate and etc.
- Monitor system metrics, thread states and cpu usage, gc statistics, and etc.
- Supports command line interactive mode, with auto-complete feature enabled.
- Supports telnet and websocket, which enables both local and remote diagnostics with command line and browsers.
- Supports profiler/Flame Graph
- Support get objects in the heap that are instances of the specified class.
- Supports JDK 6+.
- Supports Linux/Mac/Windows.
Downloadarthas-boot.jar,Start with java command:
curl -O https://arthas.aliyun.com/arthas-boot.jar java -jar arthas-boot.jar
Print usage:
java -jar arthas-boot.jar -h
You can install Arthas with one single line command on Linux, Unix, and Mac. Copy the following command and paste it into the command line, then press Enter to run:
curl -L https://arthas.aliyun.com/install.sh | shThe command above will download the bootstrap script as.sh to the current directory. You can move it any other place you want, or put its location in $PATH.
You can enter its interactive interface by executing as.sh, or execute as.sh -h for more help information.
- Online Tutorials(Recommended)
- User manual
- Installation
- Download
- Quick start
- Advanced usage
- Commands
- WebConsole
- Docker
- Arthas Spring Boot Starter
- User cases
- FAQ
- Compile and debug/How to contribute
- Release Notes
See what 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.ThreadCommand1ドル.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.ArthasServer4ドル.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.DefaultSessionManager2ドル.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)
Decompile your class with one shot:
$ 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(); }
Memory compiler, compiles .java files into .class files in memory.
$ mc /tmp/Test.java
Load the external *.class files to retransform/hotswap the loaded classes in JVM.
retransform /tmp/Test.class
retransform -c 327a647b /tmp/Test.class /tmp/Test\$Inner.classSearch any loaded class with detailed information.
$ 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
Get objects in the heap that are instances of the specified class.
$ vmtool --action getInstances --className java.lang.String --limit 10
@String[][
@String[com/taobao/arthas/core/shell/session/Session],
@String[com.taobao.arthas.core.shell.session.Session],
@String[com/taobao/arthas/core/shell/session/Session],
@String[com/taobao/arthas/core/shell/session/Session],
@String[com/taobao/arthas/core/shell/session/Session.class],
@String[com/taobao/arthas/core/shell/session/Session.class],
@String[com/taobao/arthas/core/shell/session/Session.class],
@String[com/],
@String[java/util/concurrent/ConcurrentHashMap$ValueIterator],
@String[java/util/concurrent/locks/LockSupport],
]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年09月18日 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)
See what is slowing down your method invocation with trace command:
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年09月18日 10:26:28;result=@ArrayList[
@RequestFacade[org.apache.catalina.connector.RequestFacade@79f922b2],
@NullPointerException[java.lang.NullPointerException],
]Monitor a specific method invocation statistics, including the total number of invocations, average response time, success rate, and every 5 seconds:
$ monitor -c 5 org.apache.dubbo.demo.provider.DemoServiceImpl sayHello
Press 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年09月20日 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年09月20日 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年09月20日 09:45:42 org.apache.dubbo.demo.provider.DemoServiceImpl sayHello 5 5 0 0.43 0.00%Record method invocation data, so that you can check the method invocation parameters, returned value, and thrown exceptions later. It works as if you could come back and replay the past method invocation via time tunnel.
$ tt -t org.apache.dubbo.demo.provider.DemoServiceImpl sayHello Press 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年09月20日 09:54:10 1.971195 true false 0x55965cca DemoServiceImpl sayHello 1001 2018年09月20日 09:54:11 0.215685 true false 0x55965cca DemoServiceImpl sayHello 1002 2018年09月20日 09:54:12 0.236303 true false 0x55965cca DemoServiceImpl sayHello 1003 2018年09月20日 09:54:13 0.159598 true false 0x55965cca DemoServiceImpl sayHello 1004 2018年09月20日 09:54:14 0.201982 true false 0x55965cca DemoServiceImpl sayHello 1005 2018年09月20日 09:54:15 0.214205 true false 0x55965cca DemoServiceImpl sayHello 1006 2018年09月20日 09:54:16 0.241863 true false 0x55965cca DemoServiceImpl sayHello 1007 2018年09月20日 09:54:17 0.305747 true false 0x55965cca DemoServiceImpl sayHello 1008 2018年09月20日 09:54:18 0.18468 true false 0x55965cca DemoServiceImpl sayHello
$ 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
$ profiler start Started [cpu] profiling
$ profiler stop
profiler output file: /tmp/demo/arthas-output/20211207-111550.html
OK
View profiler results under arthas-output via browser:
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This project exists, thanks to all the people who contributed.
- bytekit Java Bytecode Kit.
- greys-anatomy: The Arthas code base has derived from Greys, we thank for the excellent work done by Greys.
- termd: Arthas's terminal implementation is based on termd, an open source library for writing terminal applications in Java.
- crash: Arthas's text based user interface rendering is based on codes extracted from here
- cli: Arthas's command line interface implementation is based on cli, open sourced by vert.x
- compiler Arthas's memory compiler.
- Apache Commons Net Arthas's telnet client.
- async-profiler Arthas's profiler command.