logger

logger在线教程

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：

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <configuration>
  3.     <appender name="APPLICATION" class="ch.qos.logback.core.rolling.RollingFileAppender">
  4.         <file>app.log</file>
  5.         <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
  6.             <fileNamePattern>mylog-%d{yyyy-MM-dd}.%i.txt</fileNamePattern>
  7.             <maxFileSize>100MB</maxFileSize>
  8.             <maxHistory>60</maxHistory>
  9.             <totalSizeCap>2GB</totalSizeCap>
  10.         </rollingPolicy>
  11.         <encoder>
  12.             <pattern>%logger{35} - %msg%n</pattern>
  13.         </encoder>
  14.     </appender>
  16.     <appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
  17.         <appender-ref ref="APPLICATION" />
  18.     </appender>
  20.     <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
  21.         <encoder>
  22.             <pattern>%-4relative [%thread] %-5level %logger{35} - %msg %n
  23.             </pattern>
  24.             <charset>utf8</charset>
  25.         </encoder>
  26.     </appender>
  28.     <root level="INFO">
  29.         <appender-ref ref="CONSOLE" />
  30.         <appender-ref ref="ASYNC" />
  31.     </root>
  32. </configuration>

使用logger命令打印的结果是：

  1. [arthas@2062]$ logger
  2.  name                                   ROOT
  3.  class                                  ch.qos.logback.classic.Logger
  4.  classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
  5.  classLoaderHash                        2a139a55
  6.  level                                  INFO
  7.  effectiveLevel                         INFO
  8.  additivity                             true
  9.  codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
  10.  appenders                              name            CONSOLE
  11.                                         class           ch.qos.logback.core.ConsoleAppender
  12.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  13.                                         classLoaderHash 2a139a55
  14.                                         target          System.out
  15.                                         name            APPLICATION
  16.                                         class           ch.qos.logback.core.rolling.RollingFileAppender
  17.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  18.                                         classLoaderHash 2a139a55
  19.                                         file            app.log
  20.                                         name            ASYNC
  21.                                         class           ch.qos.logback.classic.AsyncAppender
  22.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  23.                                         classLoaderHash 2a139a55
  24.                                         appenderRef     [APPLICATION]

从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appenderRef是APPLICATION，即异步输出到文件里

查看指定名字的logger信息

  1. [arthas@2062]$ logger -n org.springframework.web
  2.  name                                   org.springframework.web
  3.  class                                  ch.qos.logback.classic.Logger
  4.  classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
  5.  classLoaderHash                        2a139a55
  6.  level                                  null
  7.  effectiveLevel                         INFO
  8.  additivity                             true
  9.  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>

  1. [arthas@2062]$ logger -c 2a139a55
  2.  name                                   ROOT
  3.  class                                  ch.qos.logback.classic.Logger
  4.  classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
  5.  classLoaderHash                        2a139a55
  6.  level                                  DEBUG
  7.  effectiveLevel                         DEBUG
  8.  additivity                             true
  9.  codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
  10.  appenders                              name            CONSOLE
  11.                                         class           ch.qos.logback.core.ConsoleAppender
  12.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  13.                                         classLoaderHash 2a139a55
  14.                                         target          System.out
  15.                                         name            APPLICATION
  16.                                         class           ch.qos.logback.core.rolling.RollingFileAppender
  17.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  18.                                         classLoaderHash 2a139a55
  19.                                         file            app.log
  20.                                         name            ASYNC
  21.                                         class           ch.qos.logback.classic.AsyncAppender
  22.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  23.                                         classLoaderHash 2a139a55
  24.                                         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

  1. [arthas@2062]$ logger --name ROOT --level debug
  2. 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：

  1. [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。

  1. [arthas@2062]$ logger --include-no-appender
  2.  name                                   ROOT
  3.  class                                  ch.qos.logback.classic.Logger
  4.  classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
  5.  classLoaderHash                        2a139a55
  6.  level                                  DEBUG
  7.  effectiveLevel                         DEBUG
  8.  additivity                             true
  9.  codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
  10.  appenders                              name            CONSOLE
  11.                                         class           ch.qos.logback.core.ConsoleAppender
  12.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  13.                                         classLoaderHash 2a139a55
  14.                                         target          System.out
  15.                                         name            APPLICATION
  16.                                         class           ch.qos.logback.core.rolling.RollingFileAppender
  17.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  18.                                         classLoaderHash 2a139a55
  19.                                         file            app.log
  20.                                         name            ASYNC
  21.                                         class           ch.qos.logback.classic.AsyncAppender
  22.                                         classLoader     sun.misc.Launcher$AppClassLoader@2a139a55
  23.                                         classLoaderHash 2a139a55
  24.                                         appenderRef     [APPLICATION]
  26.  name                                   com
  27.  class                                  ch.qos.logback.classic.Logger
  28.  classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
  29.  classLoaderHash                        2a139a55
  30.  level                                  null
  31.  effectiveLevel                         DEBUG
  32.  additivity                             true
  33.  codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
  35.  name                                   com.alibaba
  36.  class                                  ch.qos.logback.classic.Logger
  37.  classLoader                            sun.misc.Launcher$AppClassLoader@2a139a55
  38.  classLoaderHash                        2a139a55
  39.  level                                  null
  40.  effectiveLevel                         DEBUG
  41.  additivity                             true
  42.  codeSource                             file:/Users/hengyunabc/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar
  43. ...