User development, A new message was posted in the thread "Entity Manager with BMT and Transaction Timeout": http://community.jboss.org/message/528190#528190 Author : Alexander Hartner Profile : http://community.jboss.org/people/ejb3workshop Message: -------------------------------------------------------------- When running small loads on our application all is working fine, however under heavy concurrent load we consistently get the following exception.   My suspicious were that the underlying JTA transaction has timed-out and that the entity manager session was closed, so I tried increasing the global transaction timeout from 300 to 3600.     However this did not resolve my problem. Shortly (between 5 to 10 minutes) after starting the transaction the same exception occured again. I am injecting a UserTransaction as well as an EntityManager into a MessageDrivenBean and then manage the transaction myself. I found some posts that suggest in this case I have to join the EntityManager to the JTA transaction using +entityManger.joinTransaction()+ which I wasn't doing up to this point. It seemed to have had a positive impact, but I am still testing if this was really the cause of the problem.   What I am looking for is some clarification on if this is really the case that I have to join the transaction and if I don't join where the timeout for the entity manager is configured. I had a look at the Hibernate documentation, but didn't find any reference to a timeout, other then on the entity cache.   Ideally I would like to resolve this issue by changing my environment rather then the application.   Thanks in advance Alex -------------------------------------------------------------- To reply to this message visit the message page: http://community.jboss.org/message/528190#528190