目录

logger

logger在线教程在新窗口打开

提示

查看 logger 信息,更新 logger level

使用参考

查看所有 logger 信息

以下面的logback.xml为例:

<?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>

使用logger命令打印的结果是:

[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]

appenders的信息里,可以看到

  • CONSOLE logger 的 target 是System.out
  • APPLICATION logger 是RollingFileAppender,它的 file 是app.log
  • ASYNC它的appenderRefAPPLICATION,即异步输出到文件里

查看指定名字的 logger 信息

[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

查看指定 classloader 的 logger 信息

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>

[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]

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:

logger --classLoaderClass sun.misc.Launcher$AppClassLoader

  • 注: 这里 classLoaderClass 在 java 8 是 sun.misc.Launcher$AppClassLoader,而java 11的classloader是jdk.internal.loader.ClassLoaders$AppClassLoader。

--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。

更新 logger level

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

指定 classloader 更新 logger level

默认情况下,logger 命令会在 SystemClassloader 下执行,如果应用是传统的war应用,或者 spring boot fat jar 启动的应用,那么需要指定 classloader。

可以先用 sc -d yourClassName 来查看具体的 classloader hashcode,然后在更新 level 时指定 classloader:

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

查看没有 appender 的 logger 的信息

默认情况下,logger命令只打印有 appender 的 logger 的信息。如果想查看没有appender的 logger 的信息,可以加上参数--include-no-appender

注意,通常输出结果会很长。

[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
...