JBoss - Java heap retention in org.apache.log4j.helpers.BoundedFIFO

Environment

• JBoss

Issue

• java.lang.OutOfMemoryError: Java heap
• Java heap inspection shows rentention in multiple instances of org.apache.log4j.helpers.BoundedFIFO.

Resolution

Replace AsyncAppender with FileAppender:

How do I replace the AsyncAppender with a FileAppender on JBoss?

Root Cause

Poor response times and throughput can be the result of using the AsyncAppender, which can lead to heap retention. The AsyncAppender does not always improve logging throughput. A significant number of CPU cycles are spent managing the bounded queue and synchronizing the dispatcher thread with various client threads. Logging each event will take a little longer to complete; however, appending those events will hopefully take place at times where other threads are idle, either waiting for new input to process or blocked on I/O intensive operations. Thus, I/O bound applications will benefit from asynchronous logging while CPU bound applications will not.

Diagnostic Steps

• Get a heap dump and analyze it and verify the retention is in org.apache.log4j.helpers.BoundedFIFO:
  • How do I create a Java heap dump?
  • How do I analyze a Java heap dump?
• Check JBOSS_HOME/server/SERVERCONF/conf/jboss-log4j.xml to see if the AsyncAppender is being used.

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