Thursday, December 23, 2010

Debugging Log4j issues


Handy for log4j issues

Set the following switch when you start the JVM to see what log4j is upto.


Check for log4j output. This will tell where it is loading its configuration from.

Note be careful with multiple webapps having multiple log4j.xml or These can override your settings.

This next section is not true.. Its was actually caused by log4j delayed write to log file.. However I'm still including it because the detection techniques are useful.

(My actual problem was incredibly simple, and I shoudl have checked this first, but I made an assumption, and as we all know assumption is the mother of all F£$k ups.. The tool I was working on was using Simple Logging Facade for Java (SLF4J).. The developpers had simply included the slf4j-jdk.jar fil in the classpath instead of the slf4j-log4j.jar. Fixing my problem was simply a case of replacing the wrong jar. USing the log4j debugger was useful however in pinpointing what configuration files were ben picked up.

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