I am going to go out on a limb here and say that someone modified the server's source code because I cannot see any such logging statements in the source I have.
What version of JBoss AS are you using?
If you take a thread dump, what are the threads doing?
I'm using Jboss 4.0.3 and i have many threads running simultaneously. Each thread will do some process.
OK, I see the debug statements in 4.0.3. This means that the app server caught an exception and is now throwing another exception. Unfortunately, the exception stack trace does not get printed out until after this processing is done, so I cannot ask you to look for a stack trace - there is none yet.
I know that there will be a lot of threads, the question is what are they doing? Try this. Take a thread dump, wait a minute, take another. Compare them. Look for threads stuck in application code, or doing anything other what waiting on input queues.
Finally, this is the web services forum, not really the proper place for this question.