When I update a property of my domain class, it does not update the respective database table after committing the transaction. No SQL Update command get executed, even invoking Session.flush() manually. Session.isDirty() returns false. However, the property of object in the persistent context is changed.

This occurs when I implements the long-conversation approach using ThreadLocal pattern. If (for testing-sake) I use the same Session instance in all threads (i.e. singleton session), this problem will not occur.

I would be really appreciate if anyone could provided me some suggestion on the possible causes of this kind of problem, so that I could try to pinpoint and investigate into the right directions. I'm kind of don't know where to go right now.

Hibernate version: 3.2GA

Name and version of the database you are using:
HSQLDB 1.8 Server/Standalone