afaik, the job executor threads first try to write their name in a job before they execute it. that update should be guarded with optimistic locking. if multiple threads try to do this at the same time, all but one should get an exception and they have to rollback. i think this requires READ_COMMITTED as hibernate optimistic locking requires isolation level READ_COMMITTED on the jdbc connections. so please be more specific to the problem in the current code and what changes you want to apply and why. the LockMode.UPGRADE_NOWAIT is not preferred as not all databases support LockMode.UPGRADE. that is why we opted for optimistic locking instead. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4122229#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...