[hibernate-dev] JTA synchronizations on WildFly

[Steve Ebersole]

Isn't the general approach is for "compensating actions" to be run in a
separate transaction?

On Tue, Mar 10, 2015 at 10:11 AM, Scott Marlow <smarlow at redhat.com> wrote:

> I just saw the below email response after I sent the last one.  Sorry
> about that, will respond here also.  :)
>
> On 03/10/2015 09:14 AM, Emmanuel Bernard wrote:
> > Ah synchronization ordering, it never gets old :) Steve might remember
> better but I don’t think we ever managed to convice the tx team to offer
> guaranteed ordering.
>
> We started discussing synchronization ordering as well (within the
> interposed group) and there is a WildFly specific code change being
> worked on to always run the JCA sync last (so IronJacamar can delist a
> resource that would of otherwise been leaked).
>
> >
> > Your workaround seems fine (if there is a JtaPlaform) but when we add
> more logic to your onRollback calls, we might want to offer access tot he
> Session to try compensating for example. In which case, we would be in
> trouble with the closed session. I don’t have a good idea.
>
> Hmm, for the new SPI that deals with registering "concurrency safe"
> OnRollback calls, I wonder if we should have an ordering priority, so
> that the session clear/OGM operations list presentation, can always run
> before the JPA container closes the session.  In a discussion about
> changing the TM level Sync ordering for an unknown set of Syncs, we
> talked about specifying an ordering priority for registered Syncs, that
> idea will probably be useful for ordering the OnRollback calls if we
> enable that.
>
> >
> > I am a bit surprised WildFly closes the session but that might be per
> spec that the container manages these calls.
>
> Yes, only for a transaction scoped entity manager, do we have to close
> the session after the transaction ends.  We don't do this for
> application managed (application needs to call EM.close()).  For
> extended persistence contexts, we close the session, after the last
> referencing stateful bean is destroyed (tracking is done in the JPA
> container).
>
> Scott
>
> >
> >> On 10 Mar 2015, at 14:03, Gunnar Morling <gunnar at hibernate.org> wrote:
> >>
> >> Hi,
> >>
> >> I'm trying to perform a specific action upon transaction rollback.
> >>
> >> Assuming this could be done using a custom
> >> javax.transaction.Synchronization, I tried to register a
> synchronization as
> >> follows:
> >>
> >>     TransactionImplementor transaction = ...; // e.g. a CMTTransaction
> >>     transaction.registerSynchronization( new MySync() );
> >>
> >> And indeed beforeCompletion() is invoked as expected. But
> afterCompletion()
> >> never is. I debugged this a bit on WildFly and observed the following:
> >>
> >> * Hibernate ORM registers RegisteredSynchronization with JTA.
> >> RegisteredSynchronization manages (indirectly, through
> >> TransactionCoordinator, SynchronizationRegistry etc.) those
> >> synchronizations added through
> o.h.t.Transaction.registerSynchronization()
> >> * WildFly (specifically, TransactionUtil [1]) registers its own
> >> SessionSynchronization
> >> for closing the entity manager/session
> >>
> >> Now that second synchronization is called first, closing the session.
> Upon
> >> SessionImpl#close(), the SynchronizationRegistry is cleared. Then when
> >> afterComplection() is called on RegisteredSynchronization afterwards,
> any
> >> previously registered delegate synchronizations are gone already and
> thus
> >> do not get invoked.
> >>
> >> I believe I found a workaround for my case by registering my
> >> synchronization through JtaPlatform#registerSynchronization() (which
> >> registers it with the actual JTA transaction).
> >>
> >> My questions are:
> >>
> >> * Is this behaviour expected?
> >> * Is the work-around of doing the registration via JtaPlatform viable or
> >> are there any drawbacks which I'm not aware of?
> >>
> >> Thanks,
> >>
> >> --Gunnar
> >>
> >> [1]
> >>
> https://github.com/wildfly/wildfly/blob/master/jpa/src/main/java/org/jboss/as/jpa/transaction/TransactionUtil.java
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> >
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