Hello!

I'm just starting to use hibernate and keep getting this error from one of the entities:

13:36:59,398 ERROR [HibernateEngine] Failed to create job state
13:36:59,398 ERROR [BtExecuteAlertRulesImpl] Failed to set ready state for job 1
com.ikea.ebcopfc01.PersisterException: The generated identifier is already in use: [com.ikea.ebcopfc01.opfc.vo.VoJobState#1] at com.ikea.ebcopfc01.HibernateEngine.createJobState(HibernateEngine.java:391)
at com.ikea.ebcopfc01.opfc.bef.BefJobState.setReadyState(BefJobState.java:29)

I get this error the second time hibernate is trying to create a row with id = 1 even though this row has been deleted by another session (in some other thread) or by myself directly.

The mapping file looks like this:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="com.ikea.ebcopfc01.opfc.vo.VoJobState" table="TMP_JOB_STATE_T">
<id column="JOB_ID" name="jobId" type="long">
<generator class="assigned"/>
</id>
</class>
</hibernate-mapping>

And the code:

try
{
reconnect();
mSession.save(pJobState);
mSession.flush();
}
catch (Exception e)
{
cCat.error("Failed to create job state");
throw new PersisterException(e);
}
finally
{
disconnect();
}

I never close the session, I just reconnect & disconnect from the underlying datasource. With all other entities this seems to work fine.

Any ideas?

Best regards,
Pelle P

Do you ever commit the transaction? If not do so.

I'm running this inside websphere which is taking care of my transactions. And the doco tells me that I don't have to commit if I'm using a JTA datasource:

sess.connection().commit(); // not necessary for JTA datasource

Regards,
Pelle P

Is it the Hibernate session cache that makes this happen? Hibernate seems to remember that it has used a certain id and refuses to create a new entity with the same identifier, even though the entity with this id has been removed from the db by another session.

This makes me concerned about how Hibernate works in a multiuser/multithreaded environment. If thread A retrieves an entity and thread B updates it, how will thread A know if it's working with cached data? Or as is the case above, thread A adds an entity, thread B removes it, how is A notified if it's using a cache?

This is rather critical for me to understand so I'd appreciate a comment.

Regards,
Pelle P

Please read the Hibernate manual and look at the code example. The Hibernate Session is transaction-scoped. You should close() it at the end of an "application transaction".

I've read the manual several times, apparently without understanding this. I guess it was the following lines in the Session API doco that convinced me that I didn't have to close the session:

public Connection close()
throws HibernateException

End the Session by disconnecting from the JDBC connection and cleaning up. It is not strictly necessary to close() the Session but you must at least disconnect() it.

So, I just disconnect.

Regards,
Pelle P