Zombie threads eating my brainz (J2EE, Tomcat, Hibernate, Quartz)

java tomcat jakarta-ee multithreading quartz-scheduler

Try to increase the logging level of org.quartz.simpl.SimpleThreadPool to debug to get more information.
If that does not work, try a logging listener. Quartz has a JobListener interface, which is specified in its tutorial. A listener can help you trace job execution. Maybe jobs just don't finish and get deadlocked.
Configure org.quartz.threadPool.threadCount to stop running out of threads.

update:

Also, you might want to take a thread dump and see the thread stats. visual vm has a plugin called TDA, or you can use Thread dump analyzer directly.
Just in case, check the quartz version to see if there is no known bug.

java tomcat jakarta-ee multithreading quartz-scheduler

Have you had a look with jvisualvm - it gives some more information.

Also, get stack traces to see what the threads are actually waiting on. You might have an aha-feeling right there.

CodeHunter