It really looks like a memory leak trouble. If you run a jboss instance without any application it won't happen. So your application is causing it. Is there any Thread or ThreadPool on it? can you describe about your architecture? To detect memory leaks you should make profile of your application. I like to use http://www.eclipse.org/mat/ , But there is a lot of others tools ( yourkit ... ). Take a dump of your heap with jmap and check your hprof file on your profile tool.