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## Arthas
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[](https://travis-ci.org/alibaba/arthas)
[](https://codecov.io/gh/alibaba/arthas)
[](http://isitmaintained.com/project/alibaba/arthas "Average time to resolve an issue")
[](http://isitmaintained.com/project/alibaba/arthas "Percentage of issues still open")
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`Arthas` is a Java Diagnostic tool open sourced by Alibaba.
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Arthas help developers in trouble-shooting production issues for Java applications without modifying code or restarting servers.
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[中文说明 ](README_CN.md ) (For Chinese Documentation)
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### Background
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Often times, the production system network is inaccessible from local development environment. If issues are encountered in production systems, it is impossible to use IDE to debug the application remotely. More importantly, debugging in production environment is unacceptable, as it will suspend all the threads, which leads to blocking of business services.
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Developers could always try to reproduce the same issue on the test/staging environment. However, this is tricky as some issues cannot be be reproduced easily on a different environment, or even disappear once restarted.
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And if you're thinking of adding some logs to your code to help trouble-shoot 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.
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Arthas was built to solve these issues. A developer can trouble-shoot 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.
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### Key features
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* Check whether a class is loaded? Or where the class is loaded from? (Useful for trouble-shooting jar file conflicts)
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* Decompile a class to ensure the code is running as expected.
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* View classloader statistics, e.g. the number of classloaders, the number of classes loaded per classloader, the classloader hierarchy, possible classloader leaks, etc.
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* View the method invocation details, e.g. method parameter, return object, thrown exception, and etc.
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* Check the stack trace of specified method invocation. This is useful when a developers wants to know the caller of the said method.
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* Trace the method invocation to find slow sub-invocations.
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* 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.
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### Quick start
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#### Linux/Unix/Mac
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Install Arthas:
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```
curl -L https://alibaba.github.io/arthas/install.sh | sh
```
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Start Arthas:
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```
./as.sh
```
#### Windows
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1. Click [](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 of `bin.zip` .
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2. Unzip the file.
3. Go to the bin directory
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4. Run the following command `as.bat $PID`
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### Documentation
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English version is on the way, if you would like to contribute, please leave a message [here ](https://github.com/alibaba/arthas/issues/51 )
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* [User manual ](https://alibaba.github.io/arthas/en )
* [Installation ](https://alibaba.github.io/arthas/en/install-detail.html )
* [Quick start ](https://alibaba.github.io/arthas/en/quick-start.html )
* [Advanced usage ](https://alibaba.github.io/arthas/en/advanced-use.html )
* [Questions and answers ](https://github.com/alibaba/arthas/issues?utf8=%E2%9C%93&q=label%3Aquestion-answered+ )
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* [How to contribute ](https://github.com/alibaba/arthas/blob/master/CONTRIBUTING.md )
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### Feature Showcase
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#### Dashboard
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* https://alibaba.github.io/arthas/en/dashboard
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#### Thread
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See what is eating your cpu (ranked by top cpu usage) and what is going on there in one glance:
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```
$ 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
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Decompile your class with one shot:
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```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
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Search any loaded class with detailed information.
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```
$ 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
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View the call stack of `test.arthas.TestStack#doGet` :
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```
$ 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
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See what is slowing down your method invocation with trace command:
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#### Watch
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Watch the first parameter and thrown exception of `test.arthas.TestWatch#doGet` only if it throws exception.
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```
$ 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],
]
```
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#### Monitor
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Monitor a specific method invocation statistics, including total number of invocations, average response time, success rate, every 5 seconds:
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```
$ 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
----------------------------------------------------------------------------------------------------------------------------
2018-09-20 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 0.00%
```
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#### Time Tunnel(tt)
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Record method invocation data, so that you can check the method invocation parameters, returned value and thrown exception later. It works as if you could come back and replay the past method invocation via time tunnel.
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```
$ 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 2018-09-20 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
```
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#### 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
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* https://alibaba.github.io/arthas/en/web-console
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### Credit
* [greys-anatomy ](https://github.com/oldmanpushcart/greys-anatomy ): The Arthas code base has derived from Greys, we thank for the excellent work done by Greys.
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* [termd ](https://github.com/termd/termd ): Arthas's terminal implementation is based on termd, an open source library for writing terminal applications in Java.
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* [crash ](https://github.com/crashub/crash ): Arthas's text based user interface rendering is based on codes extracted from [here ](https://github.com/crashub/crash/tree/1.3.2/shell )
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* [cli ](https://github.com/eclipse-vertx/vert.x/tree/master/src/main/java/io/vertx/core/cli ): Arthas's command line interface implementation is based on cli, open sourced by vert.x
