Another program to find hot threads in Java VM

Many people know the GUI tools, such as jconsole and JTop, and maybe jvisualvm in latest JDK releases, to monitor and analyze JVM performance.

The tools jconsole together with JTop can be used to indentify threads that take most of the CPU usage. However, they work under GUI environment. In case you work in UNIX, without XServer, plus you don't have the JMX agent started, you may not have such luxury. It may be rare, but did happen in my case: HP UX, no XServer, cannot be attached to another XServer due to production firewall, the JMX agent is not started. Anyway, it's very frustrating.

Here's a tool can benefit the above case: http://weblogs.java.net/blog/brucechapman/archive/2008/03/hot_threads.html. It takes a process id as input, and prints top threads that take most of the CPU usage. In HP UX environemnt, I have to include tools.jar in the classpath:

    ${JAVA_HOME}/bin/java -Xbootclasspath/a:${JAVA_HOME}/lib/tools.jar -jar HotThread.jar 

Without tools.jar, it gives error that "java.lang.NoClassDefFoundError: com/sun/tools/attach/VirtualMachine".
Tried this in development environment, but didn't have chance to try it in production, due to lengthy procedures. Sigh...