import{_ as e,o as l,c as t,a,b as c,e as s,d as i,r as o}from"./app.391b0e4e.js";const p={},r=a("h1",{id:"logger",tabindex:"-1"},[a("a",{class:"header-anchor",href:"#logger","aria-hidden":"true"},"#"),s(" logger")],-1),d={href:"https://arthas.aliyun.com/doc/arthas-tutorials?language=en&id=command-logger",target:"_blank",rel:"noopener noreferrer"},u=a("code",null,"logger",-1),v=s(" online tutorial"),g=i(`

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Print the logger information, update the logger level

Usage

Take the following logback.xml as an example:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <appender name="APPLICATION" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>app.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
            <fileNamePattern>mylog-%d{yyyy-MM-dd}.%i.txt</fileNamePattern>
            <maxFileSize>100MB</maxFileSize>
            <maxHistory>60</maxHistory>
            <totalSizeCap>2GB</totalSizeCap>
        </rollingPolicy>
        <encoder>
            <pattern>%logger{35} - %msg%n</pattern>
        </encoder>
    </appender>

    <appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
        <appender-ref ref="APPLICATION" />
    </appender>

    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%-4relative [%thread] %-5level %logger{35} - %msg %n
            </pattern>
            <charset>utf8</charset>
        </encoder>
    </appender>

    <root level="INFO">
        <appender-ref ref="CONSOLE" />
        <appender-ref ref="ASYNC" />
    </root>
</configuration>

The result of the logger command:

[arthas@2062]$ logger
 name                                   ROOT
 class                                  ch.qos.logback.classic.Logger
 classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
 classLoaderHash                        2a139a55
 level                                  INFO
 effectiveLevel                         INFO
 additivity                             true
 codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
 appenders                              name            CONSOLE
                                        class           ch.qos.logback.core.ConsoleAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        target          System.out
                                        name            APPLICATION
                                        class           ch.qos.logback.core.rolling.RollingFileAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        file            app.log
                                        name            ASYNC
                                        class           ch.qos.logback.classic.AsyncAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        appenderRef     [APPLICATION]

In the appenders section:

View logger information for the special name

[arthas@2062]$ logger -n org.springframework.web
 name                                   org.springframework.web
 class                                  ch.qos.logback.classic.Logger
 classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
 classLoaderHash                        2a139a55
 level                                  null
 effectiveLevel                         INFO
 additivity                             true
 codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar

View logger information for the special classloader

Note that the hashcode changes, you need to check the current ClassLoader information first, and extract the hashcode corresponding to the ClassLoader.

if you use-c, you have to manually type hashcode by -c <hashcode>.

[arthas@2062]$ logger -c 2a139a55
 name                                   ROOT
 class                                  ch.qos.logback.classic.Logger
 classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
 classLoaderHash                        2a139a55
 level                                  DEBUG
 effectiveLevel                         DEBUG
 additivity                             true
 codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
 appenders                              name            CONSOLE
                                        class           ch.qos.logback.core.ConsoleAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        target          System.out
                                        name            APPLICATION
                                        class           ch.qos.logback.core.rolling.RollingFileAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        file            app.log
                                        name            ASYNC
                                        class           ch.qos.logback.classic.AsyncAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        appenderRef     [APPLICATION]

For classloader with only one instance, it can be specified by --classLoaderClass using class name, which is more convenient to use.

logger --classLoaderClass sun.misc.Launcher$AppClassLoader

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.

Update logger level

[arthas@2062]$ logger --name ROOT --level debug
update logger level success.

Speecify classloader to update logger level

By default\uFF0Clogger command will be executed under SystemClassloader, if the application is a traditional war, or using spring boot fat jar, then it needs to specify classloader\u3002

You can first use sc -d yourClassName to check specified classloader hashcode\uFF0Cthen specify classloader when updating logger level:

[arthas@2062]$ logger -c 2a139a55 --name ROOT --level debug

View the logger information without appenders

By default, the logger command only prints information about the logger with appenders. If you want to see information about loggers without appender, you can use the parameter --include-no-appender.

Note that the output will usually be very long.

[arthas@2062]$ logger --include-no-appender
 name                                   ROOT
 class                                  ch.qos.logback.classic.Logger
 classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
 classLoaderHash                        2a139a55
 level                                  DEBUG
 effectiveLevel                         DEBUG
 additivity                             true
 codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
 appenders                              name            CONSOLE
                                        class           ch.qos.logback.core.ConsoleAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        target          System.out
                                        name            APPLICATION
                                        class           ch.qos.logback.core.rolling.RollingFileAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        file            app.log
                                        name            ASYNC
                                        class           ch.qos.logback.classic.AsyncAppender
                                        classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
                                        classLoaderHash 2a139a55
                                        appenderRef     [APPLICATION]

 name                                   com
 class                                  ch.qos.logback.classic.Logger
 classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
 classLoaderHash                        2a139a55
 level                                  null
 effectiveLevel                         DEBUG
 additivity                             true
 codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar

 name                                   com.alibaba
 class                                  ch.qos.logback.classic.Logger
 classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
 classLoaderHash                        2a139a55
 level                                  null
 effectiveLevel                         DEBUG
 additivity                             true
 codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
...
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