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

Fri Mar 13 17:54:15 EDT 2009

Hi,
about this issue (HSEARCH-178) I've implemented a patch following your
directions and
your idea is working very well, but I'm having some trouble about the
configuration
of listeners.

An additional flush listener is needed; I've patched the
autoregistration but people
not using annotations will have to specify both
DefaultFlushEventListener and the
new IndexWorkFlushEventListener in their configuration.
I've been able to specify the pair of listeners using programmatic configuration
and using hibernate.cfg.xml but is this also possible with hibernate.properties
and persistence.xml ?
I couldn't find any docs or examples to register two event listeners for the
same event in JPA, I'm wondering if instead of adding a listener I should
not extend or wrap the DefaultFlushEventListener so to have only one
listener?

Would this work for JPA also or should I have to extend the
EJB3FlushEventListener
instead? I see it's different.

In case the JPA listener should be different than the hibernate
version, how can I
detect the listener I should register in the EventListenerRegister
autoregistration
routine?

To be backwards-compatible with our own configuration I've slightly modified
the patch to work as the old way (loading collections in flush) when
the listener
is not found; a warning is logged saying the listener should be registered.

hope we can fix this,
Sanne

2009/3/7 Emmanuel Bernard <emmanuel at hibernate.org>:
> 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
>>>>
>>>
>>
>
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