"oglueck" wrote : Ok, thanks. As the bug was fixed in 4.0.4RC1, we should be safe with 4.0.4GA. | So the pool was introduced as a fix against deadlocks. Okay, but this way the delivery order of messages is not known anymore (depends on scheduler). Couldn't that cause more trouble during bursts? No the thread pool doesn't affect the JMS semantics, it is simply there for when the protocol is doing more than one request/response, the protocol is bi-directional with requests being issued from either side "at any time". More importantly the handling of a request by one side may to lead a further request to the other side. e.g. "You just gave me a message for a receiver/session that I'm in the process of closing, please NACK that message" server -> DELIVER -> client -> NACK -> server View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4060722#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...