arthas 案例: 动态更新应用Logger Level

妖狐艹你老母 2022-12-14 09:05 162阅读 0赞

来源： [case-ognl-update-logger-level][]

# 案例: 动态更新应用Logger Level #

在这个案例里，动态修改应用的Logger Level。

## 查找UserController的ClassLoader ##

> sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash

$ sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash
     classLoaderHash   1be6f5c3

## 用ognl获取logger ##

> ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader ‘@com.example.demo.arthas.user.UserController@logger’

$ 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]],
    ]

可以知道UserController@logger实际使用的是logback。可以看到level=null，则说明实际最终的level是从root logger里来的。

## 单独设置UserController的logger level ##

> ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader ‘@com.example.demo.arthas.user.UserController@logger.setLevel(@ch.qos.logback.classic.Level@DEBUG)’

再次获取UserController@logger，可以发现已经是DEBUG了：

> ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader ‘@com.example.demo.arthas.user.UserController@logger’

$ 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=@Level[DEBUG],
        effectiveLevelInt=@Integer[10000],
        parent=@Logger[Logger[com.example.demo.arthas.user]],
        childrenList=null,
        aai=null,
        additive=@Boolean[true],
        loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
    ]

## 修改logback的全局logger level ##

> ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader ‘@org.slf4j.LoggerFactory@getLogger(“root”).setLevel(@ch.qos.logback.classic.Level@DEBUG)’

[case-ognl-update-logger-level]: https://arthas.aliyun.com/doc/arthas-tutorials.html?language=cn&id=case-ognl-update-logger-level