From quine's wiki

Main: Logging

Log4J

java - log4j rootLogger seems to inherit log level of other logger. Why? - Stack Overflow (Answer #2453554)

java - log4j rootLogger seems to inherit log level of other logger. Why? - Stack Overflow

java - Why is Log4j rootLogger not filtering log events according to event level? - Stack Overflow

Log Analysis

Sawmill

Sawmill Lite Feature List

Sawmill Pricing

Commons Logging Pitfalls

Think again before adopting the commons-logging API