arthas/README_CN.md

## Arthas

![arthas](site/src/site/sphinx/arthas.png)

English version goes [here](README.md).

`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：

0. 这个类从哪个 jar 包加载的？为什么会报各种类相关的 Exception？
0. 我改的代码为什么没有执行到？难道是我没 commit？分支搞错了？
0. 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？
0. 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！
0. 是否有一个全局视角来查看系统的运行状况？
0. 有什么办法可以监控到JVM的实时运行状态？

`Arthas`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。




### 快速开始

#### Linux/Unix/Mac

安装Arthas:

```
curl -L https://alibaba.github.io/arthas/install.sh | sh
```

启动Arthas:

```
./as.sh
```

#### Windows

1. 点击 [这里](http://search.maven.org/classic/#search%7Cga%7C1%7Cg%3A%22com.taobao.arthas%22%20AND%20a%3A%22arthas-packaging%22) 下载最新的Arthas zip包
2. 解压缩zip包.
3. 进入bin目录
4. 执行以下命令 `as.bat $PID`


### 文档

社区正在进行英文版本的翻译工作，如果您有兴趣请在 [这里](https://github.com/alibaba/arthas/issues/51)留言。

* [用户文档](https://alibaba.github.io/arthas/)
* [安装](https://alibaba.github.io/arthas/install-detail.html)
* [快速入门](https://alibaba.github.io/arthas/quick-start.html)
* [进阶使用](https://alibaba.github.io/arthas/advanced-use.html)
* [Questions and answers](https://github.com/alibaba/arthas/labels/question-answered)
* [参与贡献](https://github.com/alibaba/arthas/blob/master/CONTRIBUTING.md)


### 案例展示

#### Dashboard

* https://alibaba.github.io/arthas/dashboard

![dashboard](site/src/site/sphinx/_static/dashboard.png)

#### 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:

```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

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 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

观察方法执行的时候那个子调用比较慢:

![trace](site/src/site/sphinx/_static/trace.png)

#### 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} -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],
]
```

#### 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 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%
```

#### 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

* https://alibaba.github.io/arthas/web-console

![web console](site/src/site/sphinx/_static/web-console-local.png)