anonymous wrote : the Pool the pool should return you the new handle to the same existing ManagedConnection. Yes, that's what I thought too should happen. In fact it does most of the time. We can run for days without any problem and suddenly it occurs a couple of times in a row. The effect could depend on the load or on network conditions. Maybe the connection somehow doesn't get returned to the pool in time or something. In anycase there happens something that is not transparent to the application. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4104526#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...