Multiple transactions in a single hibernate session (with Spring)

Question

Is it possible to model the following using Hibernate + Spring.

• Open session
• Begin transaction
• Do some work
• Commit
• Begin transa

Answer 1

Yes, Hibernate's Sessions can begin and commit several transactions. What you need to do is to store open session somewhere, then reuse it. Note, that Session is not a thread-safe object, but if you're sure it won't have problems with concurrency, what you need is just to use TransactionSynchronizationUtils to bind a session to the thread resources and then unbind it when desired, you can find an example here or you can take a look at OSIV and its standard implementations.

This is a very complicated thing, it's much easier and thus desirable that you close your session right away and don't reuse it, because it may bring troubles:

• The objects inside of cache are not automatically evicted, thus your Session will grow in size until OutOfMemory.
• The objects inside of session are not flushed unless they are dirty, thus the chance that object was changed by another user is larger and larger. Ensure that only a single user is going to change writable objects.
• If some exception happens during one of steps, you have to ensure you close the session. After exception occurred inside of Session, this object is not reusable.
• If transaction was rolled back, the session is cleared by Spring, thus all your objects become detached. Make sure your discard everything if at least one of transactions was rolled back.