[hibernate-dev] HHH-3225 is hitting Hibernate Search

[Emmanuel Bernard]

We discussed the issue with Sanne and for Hibernate Search we have a  
workaround solution that does not penalize Hibernate Core. This  
solution can be applied by everybody but it's not the easiest thing on  
Earth.

The idea is to queue as you said but inside custom event listeners. In  
our case some Post* event listeners. This queue is "flushed" in a  
FlushEventListener. This new flush event listener must be registered  
*after* the default FlushEventListener.

All this does not require Hibernate Core change and requires minimal  
change to the Hibernate Search code and architecture.

On  Mar 6, 2009, at 10:15, Steve Ebersole wrote:

> Not sure what you mean by your "In theory it should not"...  The very
> nature of @PostUpdate is that it is going to be getting called  
> during a
> flush cycle...
>
> ----
>
> wrt "is it possible to move the post* event after the flush?"...
>
> There are really 2 answers.
>
> 1) According to the JPA spec, can we do this?  The quote from the
> current spec says:
> <quote>
> The PreUpdate and PostUpdate callbacks occur before and after the
> database update operations to
> entity data respectively. These database operations may occur at the
> time the entity state is updated or
> they may occur at the time state is flushed to the database (which may
> be at the end of the transaction).
> </quote>
> I don't really see anything there that discusses the time-relationship
> between the SQL UPDATE execution and the @PostUpdate callback other  
> than
> the fact that (obviously) @PostUpdate callback should come after the  
> SQL
> UPDATE is issued; but it does not seem to limit *how long after*.   
> So I
> think this is OK from the perspective of the spec.
>
> 2) Can Hibernate be changed to do this?  Well AnythingIsPossible in
> programming, so I guess the question really is *should* we change
> Hibernate to do this.  My main concern with this change is the extra
> queueing it would require and the corollary memory requirements.  What
> happens right now is that those callbacks are executed during the  
> action
> (org.hibernate.action.Executable) execution.  Flush puts them into a
> queue of actions (org.hibernate.engine.ActionQueue), from which they  
> are
> removed as they are executed.  We decided to put the post callbacks in
> the actions themselves for assurance-of-execution as well as
> encapsulation purposes, which I think are both still worthwhile.   
> What I
> could see as a potential solution would be to do something like we do
> for Actions which have "after transaction" tasks to perform:
> http://fisheye.jboss.org/browse/Hibernate/core/trunk/core/src/main/java/org/hibernate/engine/ActionQueue.java?r=16091#l271
>
> The "executions" list here is a queue of actions which we need to keep
> around for later.  I can see something like that in conjunction with a
> method on ActionQueue to process that internal 'callbacks' queue after
> the entire flush is complete.  Note that this does not address
> @PreUpdate.
>
> We can investigate that though and see what we are talking about in
> specific.
>
> -
>
> Steve Ebersole
> Project Lead
> http://hibernate.org
> steve at hibernate.org
>
> Principal Software Engineer
> JBoss, a division of Red Hat
> http://jboss.com
> http://redhat.com
> steve.ebersole at jboss.com
> steve.ebersole at redhat.com
>
>
> On Fri, 2009-03-06 at 09:07 -0500, Emmanuel Bernard wrote:
>> Ahhh
>> In theory it should not as Hibernate Search reads data in the
>> beforeCompletion phase.
>> Unless people do not apply changes in a transaction in which case we
>> need to execute the read in the post* event.
>>
>> We will check whether or not people use surrounding transactions
>> (Hibernate aware Tx either through JTA or via the direct Hibernate
>> Transaction API).
>> Alternatively, is it possible to move the post* event after the  
>> flush?
>> Or create noew events for that? That would solve everybody's issue.
>>
>> Emmanuel
>>
>> On  Mar 5, 2009, at 22:54, Steve Ebersole wrote:
>>
>>> Is this somehow different than the "attempt to load stuff into the  
>>> PC
>>> during flush" scenarios I see in any of these related issues?
>>>
>>> -
>>>
>>> Steve Ebersole
>>> Project Lead
>>> http://hibernate.org
>>> steve at hibernate.org
>>>
>>> Principal Software Engineer
>>> JBoss, a division of Red Hat
>>> http://jboss.com
>>> http://redhat.com
>>> steve.ebersole at jboss.com
>>> steve.ebersole at redhat.com
>>>
>>>
>>> On Thu, 2009-03-05 at 19:14 -0500, Emmanuel Bernard wrote:
>>>> http://opensource.atlassian.com/projects/hibernate/browse/HHH-3225
>>>>
>>>> Steve, any chance you could look at this one, it seems to hit  
>>>> HSearch
>>>> users on a regular basis.
>>>> _______________________________________________
>>>> hibernate-dev mailing list
>>>> hibernate-dev at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>>
>>
>