[jboss-user] [EJB 3.0] New message: "Entity Manager with BMT and Transaction Timeout"

[Alexander Hartner]

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:
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When running small loads on our application all is working fine, however under heavy concurrent load we consistently get the following exception.
> 2010-02-09 12:40:56,773 FATAL [com.abc.IndexOutputStream.deliverJob] failed to lazily initialize a collection of role: com.abc.entities.ChannelJob.m_jobProperties, no session or session was closed
> org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.abc.entities.ChannelJob.m_jobProperties, no session or session was closed
 
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.
 
>    <!-- JBoss Transactions JTA -->
>    <mbean code="com.arjuna.ats.jbossatx.jta.TransactionManagerService"
>       name="jboss:service=TransactionManager">
>       <attribute name="TransactionTimeout">*3600*</attribute>
>       <attribute name="ObjectStoreDir">${jboss.server.data.dir}/tx-object-store</attribute> 
>    </mbean>
 
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

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