mirror of https://github.com/alibaba/arthas.git
Hollow Man
5 years ago
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{
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"title": "Arthas 动态更新应用Logger Level 案例",
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"description": "Arthas 动态更新应用Logger Level 案例",
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"difficulty": "高级使用者",
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"time": "10分钟",
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"details": {
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"steps": [
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{
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"title": "Start demo",
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"text": "start-demo.md"
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},
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{
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"title": "Start arthas-boot",
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"text": "arthas-boot.md"
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},
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{
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"title": "动态更新应用Logger Level",
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"text": "case-ognl-update-logger-level.md"
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}
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],
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"intro": {
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"text": "intro.md"
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},
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"finish": {
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"text": "finish.md"
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},
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"assets": {
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"host01": []
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}
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},
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"environment": {
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"uilayout": "terminal",
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"showdashboard": true,
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"dashboards": [
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{
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"name": "Web Port 80",
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"port": 80
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}
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]
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},
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"backend": {
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"imageid": "java",
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"environmentsprotocol": "http"
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}
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}
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In this case, show how to dynamically modify the Logger Level.
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### Find the ClassLoader of the UserController
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`sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash`{{execute T2}}
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```bash
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$ sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash
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classLoaderHash 1be6f5c3
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```
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Please write down your classLoaderHash here since it's dynamic. In the case here, it's `1be6f5c3`.
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if you use`-c`, you have to manually type hashcode by `-c <hashcode>`.
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```bash
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$ ognl -c 1be6f5c3 @com.example.demo.arthas.user.UserController@logger
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```
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For classloader with only one instance, it can be specified by `--classLoaderClass` using class name, which is more convenient to use.
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```bash
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$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader @org.springframework.boot.SpringApplication@logger
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@Slf4jLocationAwareLog[
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FQCN=@String[org.apache.commons.logging.LogAdapter$Slf4jLocationAwareLog],
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name=@String[org.springframework.boot.SpringApplication],
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logger=@Logger[Logger[org.springframework.boot.SpringApplication]],
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]
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```
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The value of `--classloaderclass` is the class name of classloader. It can only work when it matches a unique classloader instance. The purpose is to facilitate the input of general commands. However, `-c <hashcode>` is dynamic.
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### Use ognl command to get the logger
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`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'`{{execute T2}}
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```bash
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$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'
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@Logger[
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serialVersionUID=@Long[5454405123156820674],
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FQCN=@String[ch.qos.logback.classic.Logger],
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name=@String[com.example.demo.arthas.user.UserController],
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level=null,
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effectiveLevelInt=@Integer[20000],
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parent=@Logger[Logger[com.example.demo.arthas.user]],
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childrenList=null,
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aai=null,
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additive=@Boolean[true],
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loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
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]
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```
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The user can know that `UserController@logger` actually uses logback. Because `level=null`, the actual final level is from the `root` logger.
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### Change the logger level of UserController
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`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger.setLevel(@ch.qos.logback.classic.Level@DEBUG)'`{{execute T2}}
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Get `UserController@logger` again, the user can see that it is already `DEBUG`:
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`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'`{{execute T2}}
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```bash
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$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'
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@Logger[
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serialVersionUID=@Long[5454405123156820674],
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FQCN=@String[ch.qos.logback.classic.Logger],
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name=@String[com.example.demo.arthas.user.UserController],
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level=@Level[DEBUG],
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effectiveLevelInt=@Integer[10000],
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parent=@Logger[Logger[com.example.demo.arthas.user]],
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childrenList=null,
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aai=null,
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additive=@Boolean[true],
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loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
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]
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```
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### Change the global logger level of the logback
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By getting the `root` logger, the user can modify the global logger level:
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`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@org.slf4j.LoggerFactory@getLogger("root").setLevel(@ch.qos.logback.classic.Level@DEBUG)'`{{execute T2}}
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@ -0,0 +1,6 @@
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Through this tutorial, you can know how to Change Logger Level. More advanced features can be found in the Advanced Guide below.
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* [Arthas Advanced](https://arthas.aliyun.com/doc/arthas-tutorials?language=en&id=arthas-advanced)
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* [Arthas Github](https://github.com/alibaba/arthas)
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* [Arthas Documentation](https://arthas.aliyun.com/doc/en)
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@ -0,0 +1,45 @@
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{
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"title": "Arthas Change Logger Level",
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"description": "Arthas Change Logger Level",
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"difficulty": "expert",
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"time": "10 minutes",
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"details": {
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"steps": [
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{
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"title": "Start demo",
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"text": "start-demo.md"
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},
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{
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"title": "Start arthas-boot",
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"text": "arthas-boot.md"
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},
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{
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"title": "Change Logger Level",
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"text": "case-ognl-update-logger-level.md"
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}
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],
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"intro": {
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"text": "intro.md"
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},
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"finish": {
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"text": "finish.md"
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},
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"assets": {
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"host01": []
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}
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},
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"environment": {
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"uilayout": "terminal",
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"showdashboard": true,
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"dashboards": [
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{
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"name": "Web Port 80",
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"port": 80
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}
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]
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},
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"backend": {
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"imageid": "java",
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"environmentsprotocol": "http"
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}
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}
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@ -0,0 +1,11 @@
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`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.
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`Arthas` supports JDK 6+, supports Linux/Mac/Windows.
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* Github: https://github.com/alibaba/arthas
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* Documentation: https://arthas.aliyun.com/doc/en
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@ -0,0 +1,14 @@
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Download `demo-arthas-spring-boot.jar`, and start with `java -jar` command:
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`wget https://github.com/hengyunabc/spring-boot-inside/raw/master/demo-arthas-spring-boot/demo-arthas-spring-boot.jar
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java -jar demo-arthas-spring-boot.jar`{{execute T1}}
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`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)
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After booting, access port 80: https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com
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