The IBM “Garbage Collection and Memory Visualizer” is an excellent tool for analyzing the behavior of IBM J9 JVMs used by WebSphere. What is less known is the fact that it can be used for analyzing the behavior of Sun HotSpot JVMs used by JBoss and WebLogic also.
You can get the IBM “Garbage Collection and Memory Visualizer” by downloading the IBM Support Assistant Workbench” which is based on Eclipse. It is a collection of several diagnostic tools. It is free but you need a “universal IBM user ID”. During the installation, make sure you choose “IBM Monitoring and Diagnostic Tools for Java – Garbage Collection and Memory Visualizer”.
Once started, the tool can be pointed to the GC log of your J9 or HotSpot JVM. To make the Sun HotSpot JVM log garbage collection details, you need to add the following JVM arguments to the JBoss or WebLogic startup script (change it to fit your environment):
rem ———————————-
rem Enable garbage collection logging
rem ———————————
set JAVA_OPTS=%JAVA_OPTS% -verbose:gc
set JAVA_OPTS=%JAVA_OPTS% -Xloggc:C:\Programs\jboss_4.2.1\server\lc_mysql\log\gc.log
set JAVA_OPTS=%JAVA_OPTS% -XX:+PrintGCDetails
set JAVA_OPTS=%JAVA_OPTS% -XX:+PrintGCTimeStamps
set JAVA_OPTS=%JAVA_OPTS% -XX:+PrintHeapAtGC
