arthas/tutorials/katacoda/arthas-advanced-en/case-logger-config-problem.md

In this case, show how to troubleshoot logger conflicts.

View the logger system used by the app

Take UserController as an example, it uses slf4j api, but the actual logger system used is logback.

ognl -c 1be6f5c3 '@com.example.demo.arthas.user.UserController@logger'{{execute T2}}

$ ognl -c 1be6f5c3 '@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]],
]

Find the configuration file actually loaded by the logback

ognl -c 1be6f5c3 '#map1=@org.slf4j.LoggerFactory@getLogger("root").loggerContext.objectMap, #map1.get("CONFIGURATION_WATCH_LIST")'{{execute T2}}

Use the classloader command to find possible logger configuration files

classloader -c 1be6f5c3 -r logback-spring.xml{{execute T2}}

$ classloader -c 1be6f5c3 -r logback-spring.xml
 jar:file:/Users/hengyunabc/code/java/spring-boot-inside/demo-arthas-spring-boot/target/demo-arthas-spring-boot-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes!/logback-spring.xml

Affect(row-cnt:1) cost in 13 ms.

You can know the specific source of the loaded configuration.

You can try to load files that are prone to conflict:

classloader -c 1be6f5c3 -r logback.xml{{execute T2}}

classloader -c 1be6f5c3 -r log4j.properties{{execute T2}}