Re: [Springframework-developer] Hibernate resource management issue

[Colin S. <col...@ex...>]

Juergen,

I am almost 100% sure this block of code from 
AbstractPlatformTransactionManager is wrong:
        else {
            try {
                try {
                    triggerBeforeCommit(defStatus);
                    triggerBeforeCompletion(defStatus);
                    if (status.isNewTransaction()) {
                        logger.info("Initiating transaction commit");
                        doCommit(defStatus);
                    }
                }
                catch (UnexpectedRollbackException ex) {
                    triggerAfterCompletion(defStatus, 
TransactionSynchronization.STATUS_ROLLED_BACK, ex);
                    throw ex;
                }
                catch (TransactionException ex) {
                    if (this.rollbackOnCommitFailure) {
                        doRollbackOnCommitException(defStatus, ex);
                        triggerAfterCompletion(defStatus, 
TransactionSynchronization.STATUS_ROLLED_BACK, ex);
                    }
                    else {
                        triggerAfterCompletion(defStatus, 
TransactionSynchronization.STATUS_UNKNOWN, ex);
                    }
                    throw ex;
                }
                catch (RuntimeException ex) {
                    doRollbackOnCommitException(defStatus, ex);
                    triggerAfterCompletion(defStatus, 
TransactionSynchronization.STATUS_ROLLED_BACK, ex);
                    throw ex;
                }
                catch (Error err) {
                    doRollbackOnCommitException(defStatus, err);
                    triggerAfterCompletion(defStatus, 
TransactionSynchronization.STATUS_UNKNOWN, err);
                    throw err;
                }
                triggerAfterCompletion(defStatus, 
TransactionSynchronization.STATUS_COMMITTED, null);
            }
            finally {
                cleanupAfterCompletion(defStatus);
            }
        }

triggerBeforeCommit() execute, which in the Hibernate case will force a 
flush. However, if that flush throws an exception, then
   triggerBeforeCompletion(defStatus);
never gets called. However, triggerBeforeCompletion is what is actually 
supposed to release the Hibernate session holder from the current 
thread! So in this case, the session (which is totally hosed of course), 
gets left on the thread. I believe in some environments this wouldn't 
matter that much, as the threads don't get resused. In the JBoss case, 
new requests coming in will get the existing thread, and this time, 
SessionFactoryUtils will see the session is there, and try to use it. 
Bang, it all blows up...

So for this code to work properly, what needs to happen is that 
triggerBeforeCompletion still needs to be called even if 
triggerBeforeCommit fails. While I am ok with writing the code in this 
method to handle this, I am not 100% sure this is safe in terms of all 
the other interactions that will happen as a result; mot of this code is 
your baby with me only having traced through it once in a while. So if 
you would prefer to resolve this that would be great.

Unless I am mistaken about this bug, I think it is a pretty serious one, 
and warrants an almost immediate release of a v1.0.1 of Spring...

Regards,
Colin


Colin Sampaleanu wrote:

> I am tracking down a possible Hibernate resource management issue.
>
> In a running app, some time yesterday, some code, running in a wrapped 
> transaction with Hibernate handling ORM, encountered an Oracle 
> constraint violation and threw an exception. Fine...
>
> But when I log into the app myself now via the web ui and then it gets 
> a service object to read some data, the service object is wrapped with 
> a transaction interceptor, and also a hibernate interceptor. The 
> Hibernate interceptor is already seeing a Hibernate Session existing 
> on the current thread, so it is not creating a new one. Then at the 
> end of the transaction, when the Hibernate session is attempted to be 
> flushed, Hibernate tries to write out the old bad data from yesterday.
>
> What this essentially means is that when the error from yesterday 
> happened, the session did not get released from the thread, and has 
> been sticking around all this time. When I came via struts, I was 
> given the same thread as yesterday by the appserver, and the old 
> invalid session was still on it. The problem is not that it's reusing 
> that session, but why it was ever left that the day before.
>
> Will try to duplicate this...