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ejb3workshop.com
 Post subject: Entity Manager with BMT and Transaction Timeout
PostPosted: Thu Feb 25, 2010 12:53 pm 
Newbie

Joined: Thu Feb 12, 2009 10:00 am
Posts: 18
When running small loads on our application all is working fine, however under heavy concurrent load we consistently get the following exception.

Quote:
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 in jboss-service.xml

Code:
   <!-- 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 however this had little impact and the problem persists.

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.

I understand that this problem my not directly be linked to hibernate as I am using the hibernate entity manager within JBoss 4.2.3GA. I do however hope that somebody can point me in the right direction on how to further analyze this issue

Thanks in advance
Alex
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ejb3workshop.com
 Post subject: Re: Entity Manager with BMT and Transaction Timeout
PostPosted: Thu Feb 25, 2010 12:57 pm 
Newbie

Joined: Thu Feb 12, 2009 10:00 am
Posts: 18
First the MDB which shows the injection of an entityManager, usertransaction and a datasource:
Code:
...
@MessageDriven(name = "WorkListener", activationConfig = {
        @ActivationConfigProperty(propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge"),
        @ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue"),
        @ActivationConfigProperty(propertyName = "destination", propertyValue = "queue/abc/WorkMessages")
})
@TransactionManagement(TransactionManagementType.BEAN)
public class WorkListener  implements MessageListener {

    @PersistenceContext(unitName = "entityManager")
    protected EntityManager entityManager;

    @Resource(name = "jdbc/abcDSNoTX")
    DataSource datasource;

    @Resource
    private UserTransaction userTransaction;

    public void onMessage(Message message) {
        try {         
            Processor processor = new Processor(entityManager, userTransaction, datasource);
            processor.process(message);
....


Then further down the stack we begin a new userTransaction and load some entity via the entity manager

Code:
...
m_userTransaction.begin();
Account account = m_entityManager.find(Account.class, accountId);
...
account.getRelatedAccounts();


However further down the stack we access a collection on the account which loads further linked entities and failes with the LazyInitializationException.

This problem only occurs under load and is most likely caused by a slow down while accessing the database. However I am not too concerned about performance at this stage, just want to know how I can debug this issue and see what happened to my entity manager session. My suspicion is that since I am using a User Transaction that the global timeout which I set to 3600 (=1 hour) is not applied. If this is the case where do you set the default transaction timeout for a user transaction or the hibernate session.

PS: I am using this code to illustrate my problem. I know the exception refers to a different class. The application consists of various different classes and posting the actual code would just make things more difficult.
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ejb3workshop.com
 Post subject: Re: Entity Manager with BMT and Transaction Timeout
PostPosted: Thu Feb 25, 2010 10:30 pm 
Newbie

Joined: Thu Feb 12, 2009 10:00 am
Posts: 18
I enabled the complete hibernate context at trace level and got the following. Not really sure what to look for:

Code:
2010-02-25 23:09:00,600 TRACE [org.hibernate.transaction.CacheSynchronization] transaction before completion callback
2010-02-25 23:09:00,600 TRACE [org.hibernate.jdbc.JDBCContext] before transaction completion
2010-02-25 23:09:00,601 TRACE [org.hibernate.impl.SessionImpl] before transaction completion
2010-02-25 23:09:00,601 TRACE [org.hibernate.ejb.AbstractEntityManagerImpl] automatically flushing session
2010-02-25 23:09:00,601 TRACE [org.hibernate.impl.SessionImpl] automatically flushing session
2010-02-25 23:09:00,601 TRACE [org.hibernate.event.def.AbstractFlushingEventListener] flushing session
2010-02-25 23:09:00,601 DEBUG [org.hibernate.event.def.AbstractFlushingEventListener] processing flush-time cascades
2010-02-25 23:09:00,601 TRACE [org.hibernate.engine.Cascade] processing cascade ACTION_PERSIST_ON_FLUSH for: com.abc.entities.Batch
2010-02-25 23:09:00,601 TRACE [org.hibernate.engine.Cascade] done processing cascade ACTION_PERSIST_ON_FLUSH for: com.abc.entities.Batch
2010-02-25 23:09:00,601 DEBUG [org.hibernate.event.def.AbstractFlushingEventListener] dirty checking collections
2010-02-25 23:09:00,601 TRACE [org.hibernate.event.def.AbstractFlushingEventListener] Flushing entities and processing referenced collections
2010-02-25 22:40:12,978 INFO  [org.hibernate.ejb.Ejb3Configuration] found EJB3 Entity bean: com.abc.AuditTrailEntry
...skipping...
2010-02-25 23:09:00,601 ERROR [org.hibernate.LazyInitializationException] failed to lazily initialize a collection of role: com.abc.entities...
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