It appears that AsyncUtils thread is not bound to the server lifecycle nither marked as a daemon. So JBossAS wait for AsyncUtils to complete before it can shut down.
Does anybody has an idea on how to shutdown gracefully while AsyncUtils is running a task ?
It's probably not wise to simply end the thread at shutdown.
JBoss probably should issue a Thread.interrupt() at shutdown time. If it's not, you can either patch the code (not sure where) or file a bug. Or, interrupt the thread yourself, based on the name. (Not really clean, though.)