add Troubleshoot logger conflicts case scenario #847 (#1338)

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Hollow Man 5 years ago committed by GitHub
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在新的`Terminal 2`里,下载`arthas-boot.jar`,再用`java -jar`命令启动:
`wget https://arthas.aliyun.com/doc/arthas-boot.jar
java -jar arthas-boot.jar`{{execute T2}}
`arthas-boot`是`Arthas`的启动程序它启动后会列出所有的Java进程用户可以选择需要诊断的目标进程。
选择第一个进程,输入 `1`{{execute T2}} ,再`Enter/回车`
Attach成功之后会打印Arthas LOGO。输入 `help`{{execute T2}} 可以获取到更多的帮助信息。
![Arthas Boot](/arthas/scenarios/common-resources/assets/arthas-boot.png)

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在这个案例里展示排查logger冲突的方法。
### 查找UserController的ClassLoader
`sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash`{{execute T2}}
```bash
$ sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash
classLoaderHash 1be6f5c3
```
注意hashcode是变化的需要先查看当前的ClassLoader信息提取对应ClassLoader的hashcode。
如果你使用`-c`你需要手动输入hashcode`-c <hashcode>`
```bash
$ ognl -c 1be6f5c3 @com.example.demo.arthas.user.UserController@logger
```
对于只有唯一实例的ClassLoader可以通过`--classLoaderClass`指定class name使用起来更加方便
```bash
$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader @org.springframework.boot.SpringApplication@logger
@Slf4jLocationAwareLog[
FQCN=@String[org.apache.commons.logging.LogAdapter$Slf4jLocationAwareLog],
name=@String[org.springframework.boot.SpringApplication],
logger=@Logger[Logger[org.springframework.boot.SpringApplication]],
]
```
`--classLoaderClass` 的值是ClassLoader的类名只有匹配到唯一的ClassLoader实例时才能工作目的是方便输入通用命令而`-c <hashcode>`是动态变化的。
### 确认应用使用的logger系统
以`UserController`为例它使用的是slf4j api但实际使用到的logger系统是logback。
`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'`{{execute T2}}
```bash
$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'
@Logger[
serialVersionUID=@Long[5454405123156820674],
FQCN=@String[ch.qos.logback.classic.Logger],
name=@String[com.example.demo.arthas.user.UserController],
level=null,
effectiveLevelInt=@Integer[20000],
parent=@Logger[Logger[com.example.demo.arthas.user]],
childrenList=null,
aai=null,
additive=@Boolean[true],
loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
]
```
### 获取logback实际加载的配置文件
`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '#map1=@org.slf4j.LoggerFactory@getLogger("root").loggerContext.objectMap, #map1.get("CONFIGURATION_WATCH_LIST")'`{{execute T2}}
### 使用classloader命令查找可能存在的logger配置文件
`classloader --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader -r logback-spring.xml`{{execute T2}}
```
$ classloader --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader -r logback-spring.xml
jar:file:/Users/hengyunabc/code/java/spring-boot-inside/demo-arthas-spring-boot/target/demo-arthas-spring-boot-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes!/logback-spring.xml
Affect(row-cnt:1) cost in 13 ms.
```
可以知道加载的配置的具体来源。
可以尝试加载容易冲突的文件:
`classloader --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader -r logback.xml`{{execute T2}}
`classloader --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader -r log4j.properties`{{execute T2}}

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通过本教程基本掌握了Arthas排查logger冲突问题。更多高级特性可以在下面的进阶指南里继续了解。
* [Arthas进阶](https://arthas.aliyun.com/doc/arthas-tutorials?language=cn&id=arthas-advanced)
* [Arthas Github](https://github.com/alibaba/arthas)
* [Arthas 文档](https://arthas.aliyun.com/doc/)
欢迎关注公众号获取Arthas项目的信息源码分析案例实践。
![Arthas公众号](/arthas/scenarios/common-resources/assets/qrcode_gongzhonghao.jpg)

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{
"title": "Arthas 排查logger冲突问题 案例",
"description": "Arthas 排查logger冲突问题 案例",
"difficulty": "高级使用者",
"time": "10分钟",
"details": {
"steps": [
{
"title": "Start demo",
"text": "start-demo.md"
},
{
"title": "Start arthas-boot",
"text": "arthas-boot.md"
},
{
"title": "排查logger冲突问题",
"text": "case-logger-config-problem.md"
}
],
"intro": {
"text": "intro.md"
},
"finish": {
"text": "finish.md"
},
"assets": {
"host01": []
}
},
"environment": {
"uilayout": "terminal",
"showdashboard": true,
"dashboards": [
{
"name": "Web Port 80",
"port": 80
}
]
},
"backend": {
"imageid": "java",
"environmentsprotocol": "http"
}
}

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![Arthas](https://arthas.aliyun.com/doc/_images/arthas.png)
`Arthas` 是Alibaba开源的Java诊断工具深受开发者喜爱。在线排查问题无需重启动态跟踪Java代码实时监控JVM状态。
`Arthas` 支持JDK 6+支持Linux/Mac/Windows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。
* Github: https://github.com/alibaba/arthas
* 文档: https://arthas.aliyun.com/doc/

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下载`demo-arthas-spring-boot.jar`,再用`java -jar`命令启动:
`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`{{execute T1}}
`demo-arthas-spring-boot`是一个很简单的spring boot应用源代码[查看](https://github.com/hengyunabc/spring-boot-inside/tree/master/demo-arthas-spring-boot)
启动之后可以访问80端口 https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com
![Demo Web](/arthas/scenarios/common-resources/assets/demo-web.png)

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In the new `Terminal 2`, download `arthas-boot.jar` and start with the `java -jar` command:
`wget https://arthas.aliyun.com/doc/arthas-boot.jar
java -jar arthas-boot.jar`{{execute T2}}
`arthas-boot` is the launcher for `Arthas`. It lists all the Java processes, and the user can select the target process to be diagnosed.
Select the first process, type `1`{{execute T2}} then type `Enter`
After the Attach is successful, Arthas LOGO is printed. Enter `help`{{execute T2}} for more help.
![Arthas Boot](/arthas/scenarios/common-resources/assets/arthas-boot.png)

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In this case, show how to troubleshoot logger conflicts.
### Find the ClassLoader of the UserController
`sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash`{{execute T2}}
```bash
$ sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash
classLoaderHash 1be6f5c3
```
Please write down your classLoaderHash here since it's dynamic. In the case here, it's `1be6f5c3`.
if you use`-c`, you have to manually type hashcode by `-c <hashcode>`.
```bash
$ ognl -c 1be6f5c3 @com.example.demo.arthas.user.UserController@logger
```
For classloader with only one instance, it can be specified by `--classLoaderClass` using class name, which is more convenient to use.
```bash
$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader @org.springframework.boot.SpringApplication@logger
@Slf4jLocationAwareLog[
FQCN=@String[org.apache.commons.logging.LogAdapter$Slf4jLocationAwareLog],
name=@String[org.springframework.boot.SpringApplication],
logger=@Logger[Logger[org.springframework.boot.SpringApplication]],
]
```
The value of `--classloaderclass` is the class name of classloader. It can only work when it matches a unique classloader instance. The purpose is to facilitate the input of general commands. However, `-c <hashcode>` is dynamic.
### View the logger system used by the app
Take `UserController` as an example, it uses slf4j api, but the actual logger system used is logback.
`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'`{{execute T2}}
```bash
$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'
@Logger[
serialVersionUID=@Long[5454405123156820674],
FQCN=@String[ch.qos.logback.classic.Logger],
name=@String[com.example.demo.arthas.user.UserController],
level=null,
effectiveLevelInt=@Integer[20000],
parent=@Logger[Logger[com.example.demo.arthas.user]],
childrenList=null,
aai=null,
additive=@Boolean[true],
loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
]
```
### Find the configuration file actually loaded by the logback
`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '#map1=@org.slf4j.LoggerFactory@getLogger("root").loggerContext.objectMap, #map1.get("CONFIGURATION_WATCH_LIST")'`{{execute T2}}
### Use the classloader command to find possible logger configuration files
`classloader --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader -r logback-spring.xml`{{execute T2}}
```
$ classloader --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader -r logback-spring.xml
jar:file:/Users/hengyunabc/code/java/spring-boot-inside/demo-arthas-spring-boot/target/demo-arthas-spring-boot-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes!/logback-spring.xml
Affect(row-cnt:1) cost in 13 ms.
```
You can know the specific source of the loaded configuration.
You can try to load files that are prone to conflict:
`classloader --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader -r logback.xml`{{execute T2}}
`classloader --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader -r log4j.properties`{{execute T2}}

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Through this tutorial, you can know how to Troubleshoot logger conflicts. More advanced features can be found in the Advanced Guide below.
* [Arthas Advanced](https://arthas.aliyun.com/doc/arthas-tutorials?language=en&id=arthas-advanced)
* [Arthas Github](https://github.com/alibaba/arthas)
* [Arthas Documentation](https://arthas.aliyun.com/doc/en)

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{
"title": "Arthas Troubleshoot logger conflicts",
"description": "Arthas Troubleshoot logger conflicts",
"difficulty": "expert",
"time": "10 minutes",
"details": {
"steps": [
{
"title": "Start demo",
"text": "start-demo.md"
},
{
"title": "Start arthas-boot",
"text": "arthas-boot.md"
},
{
"title": "Troubleshoot logger conflicts",
"text": "case-logger-config-problem.md"
}
],
"intro": {
"text": "intro.md"
},
"finish": {
"text": "finish.md"
},
"assets": {
"host01": []
}
},
"environment": {
"uilayout": "terminal",
"showdashboard": true,
"dashboards": [
{
"name": "Web Port 80",
"port": 80
}
]
},
"backend": {
"imageid": "java",
"environmentsprotocol": "http"
}
}

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![Arthas](https://arthas.aliyun.com/doc/_images/arthas.png)
`Arthas` is a Java diagnostic tool open-sourced by Alibaba middleware team. Arthas helps developers in trouble-shooting issues in production environment for Java based applications without modifying code or restarting servers.
`Arthas` supports JDK 6+, supports Linux/Mac/Windows.
* Github: https://github.com/alibaba/arthas
* Documentation: https://arthas.aliyun.com/doc/en

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Download `demo-arthas-spring-boot.jar`, and start with `java -jar` command:
`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`{{execute T1}}
`demo-arthas-spring-boot` is a simple Spring Boot demo, the source code here: [View](https://github.com/hengyunabc/spring-boot-inside/tree/master/demo-arthas-spring-boot)
After booting, access port 80: https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com
![Demo Web](/arthas/scenarios/common-resources/assets/demo-web.png)
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