Looks like a bug in the thread pool error handling to me: http://jira.jboss.com/jira/browse/JBAS-5354 http://jira.jboss.com/jira/browse/JBCOMMON-47 Basically what is happening is that you have a messageProducer.send() competing with a connection.close() The close() interrupts the thread that is handling the send() on the server side and this causes the thread pool to spuriously think the thread pool is full. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4140072#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...