There's definitely something going on. ServerSessionImpl:cancel is called at the end of perfListener to place messages delivered but not consumed back on the queues. That's a regular operation... but cancel is canceling deliveries on messages that were not sent yet. I had a few problems with reference counting when I ran perfSender/perfListener this way: and perfSender -Dmessage.count=400000 -Dmessage.wamup.count=20000 and then: run two perfListener as: ant perfListener -Ddrain.queue=false ant perfListener -Ddrain.queue=false The last one won't receive 20K messages, and I believe the serverSessionImpl.cancel has a play on this bug. This is the next thing I'm going to do as soon as I'm done with paging. I just want to make sure there isn't anything bigger than expected going on here. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4172708#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...