java-debug-arthas

关键字 `arthas` `生产环境使用arthas调试java应用`

官网：[arthas](https://arthas.aliyun.com/)

## basic

在一个terminal中输入

```bash
wget https://arthas.aliyun.com/arthas-demo.jar
java -jar arthas-demo.jar
```

在另一个terminal中输入

```bash
curl -O https://arthas.aliyun.com/arthas-boot.jar
java -jar arthas-boot.jar --repo-mirror aliyun --use-http
```

arthas命令

```arthas
help
bashboard
Q/Ctrl+C # exit
thread tid # show thread statck
thread tid | grep 'main(' # show thread statck contains mainClass
sc -d *MathGame
jad demo.MathGame
watch demo.MathGame primeFactors returnObj  #
exit/quit # exit session
stop # stop arthas
```

## advanced

在一个terminal中输入

```bash
wget https://github.com/hengyunabc/spring-boot-inside/raw/master/demo-arthas-spring-boot/demo-arthas-spring-boot.jar
java -jar demo-arthas-spring-boot.jar
```

在另一个terminal中输入

```bash
java -jar arthas-boot.jar --target-ip 0.0.0.0
```

arthas命令

```arthas
sysprop # show all system properties
sysprop java.version # show by key name
sysprop | grep user # filter key
sysprop | wc -l # count key
sysprop testKey testValue  # set new value
sysenv # show all environment properties
jvm # show jvm info
keymap # show keymap
sc # show classes loaded in jvm
sc javax.servlet.Filter
sc -d javax.servlet.Filter
sc *StringUtils
sm # show methods in class
sm java.math.RoundingMode
sm -d java.math.RoundingMode
sm java.math.RoundingMode <init>
jad com.example.demo.arthas.user.UserController
ognl
ognl '@java.lang.System@out.println("hello ognl")' # 此时第一个Terminal会输出'hello ognl'
sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash\
ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader @com.example.demo.arthas.user.UserController@logger
ognl '#value1=@System@getProperty("java.home"), #value2=@System@getProperty("java.runtime.name"), {#value1, #value2}'
watch com.example.demo.arthas.user.UserController * '{params, throwExp}' # 监控请求参数，需要在浏览器端发起请求。
thread # show all thread
thread tid # show thread with id
thread -n 3 # show top 3 usage
thread -n 3 -i 5000 # show cpu usage in latest 5 second
thread -b # show blocking
```

也可以使用thread -n 3命令打印出CPU占比最高的前三个线程，这差不多是top -Hp & printf & jstack 三令合一的效果了

## ArthasHotSwap (idea插件)

修改文件内容（建议是添加打印日志，不要添加新方法/属性等变动大的内容）后，单击右键 maven编译 -> swap this class -> 热部署命令已经复制到粘贴板 -> 登录远程服务器（需要提前关闭已启动的arthas进程）粘贴并执行热部署命令（此时尽量只有一个java进程） -> 热部署成功 - 动重新启动arthas

问题：内网下怎么使用ArthasHotSwap？

热部署时会把修改后的字节码内容发送到阿里云0ss中，内网环境无法访问。将.sh文件下载到本地即可。

一个完整命令如下：

```shell
sudo echo "curl -L http://xxxtai-arthas-hot-swap.oss-cn-beijing.aliyuncs.com/public/xxx  > HotSwapScript4OneClass.sh ;
echo 'yyyy  HotSwapScript4OneClass.sh' > HotSwapScript4OneClass.md5sum;
md5sum --status -c ./HotSwapScript4OneClass.md5sum;
if [[ \$? -eq 0 ]]; then
    chmod +x HotSwapScript4OneClass.sh;
    yes | ./HotSwapScript4OneClass.sh  zzzz wwww;
else
    echo 'It is necessary to report this error to xxxtai@163.com!!!';
fi" > ArthasHotSwapMD5Check.sh; chmod +x ./ArthasHotSwapMD5Check.sh; ./ArthasHotSwapMD5Check.sh;
```

可知会得到如下文件：
- HotSwapScript4OneClass.sh
- HotSwapScript4OneClass.md5sum
- ArthasHotSwapMD5Check.sh

把.sh中curl命令都提前下载好对应的文件。

## use in docker

若docker镜像无法联网，就不要使用arthas-boot.jar。
将arthas-bin.zip （约12M）或解压后挂载到容器中，进入容器即可访问arthas。

## arthas-tunnel-server & arthas-spring-boot-starter

- copy following dependency to pom.xml

```xml
<dependency>
    <groupId>com.taobao.arthas</groupId>
    <artifactId>arthas-spring-boot-starter</artifactId>
    <version>3.3.9</version>
</dependency>
```

then copy following to application.yml

```yml
arthas:
  agent-id: abcdefg
  tunnel-server: 'ws://127.0.0.1:7777/ws'
```

agent-id will be used later.

then run springboot application
- download arthas-tunnel-server-3.3.9.jar from <https://github.com/alibaba/arthas/releases>
- run `java –jar arthas-tunnel-server-3.3.9.jar`
- visit <http://127.0.0.1:8080/>, type abcdefg in AgentId, and click connect!

```
watch com.xxx.controller.ToolController ping '{params, target, returnObj}'
watch com.xxx.controller.ToolController ping '{params[0], target, returnObj}'
```

### 异步任务

后台/异步运行一个任务
`watch org.springframework.web.servlet.DispatcherServlet getHandler returnObj >> d:/tmp/arthas-log.txt &`
查看所有任务
`jobs`
删除任务，JOB_ID由`jobs`命令展示
`kill $JOB_ID`

## 实战

### Arthas实践：是哪个Controller处理了请求？

来源：<https://hengyun.tech/arthas-springmvc-controller/>

- 运行App
- 运行 arthas `java -jar arthas-boot.jar`
  * `trace org.springframework.web.servlet.DispatcherServlet doDispatch`
  * 发送请求 `curl http://me:60001/users`
  * `watch org.springframework.web.servlet.DispatcherServlet getHandler returnObj`
  * 发送请求 `curl http://me:60001/users`

见附件[【附件】springboot-find-exact-executing-controller-by-arthas.zip](/media/attachment/2025/03/springboot-find-exact-executing-controller-by-arthas.zip)

### 查看类的静态属性
`getstatic demo.MathGame random`

### 查看内存里某个变量的值

```shell
sc -d *ValuetodaysSsoProperties
vmtool --action getInstances --className cn.valuetodays.project.webapp.eblog.web.ValuetodaysSsoProperties --limit 10
vmtool --action getInstances --className cn.valuetodays.project.webapp.eblog.web.ValuetodaysSsoProperties --express 'instances[0]'
vmtool --action getInstances --className cn.valuetodays.project.webapp.eblog.web.ValuetodaysSsoProperties --express 'instances[0].clientId'
```

## 使用

thread -n 3 占用cpu高的前3个线程

有时候我们发现应用卡住了， 这可能是因为发生了死锁或者其他锁等待问题。 为了排查这类问题， arthas提供了thread -b， 一键找出那个罪魁祸首。
 > 注意， 目前只支持找出synchronized关键字阻塞住的线程， 如果是java.util.concurrent.Lock， 目前还不支持。

trace 某个方法调用链路是什么和执行耗时是多少？
-  trace  com.simple.IndexController m  --skipJDKMethod  false
-  trace  com.simple.IndexController m

sm com.intellij.execution.rmi.RemoteServer

sc -d -f com.intellij.execution.rmi.RemoteServer

ognl '@com.intellij.execution.rmi.RemoteServer@SERVER_HOSTNAME'

getstatic com.intellij.execution.rmi.RemoteServer SERVER_HOSTNAME

ognl '@com.intellij.execution.rmi.RemoteServer@SERVER_HOSTNAME.length()'

## referer:

- <https://github.com/alibaba/arthas/releases>
- arthas doc <https://arthas.aliyun.com/doc/quick-start.html>
- ognl <https://commons.apache.org/proper/commons-ognl/language-guide.html>