Re: [eclipselink-users] Removed entity can still be found by otherentity

["Andrei Ilitchev" <andrei.ilitchev@xxxxxxxxxx>]

Do I understand correctly the scenario:
The object was deleted by em1 (and transaction was committed);
then em2 was created and found the removed object.

That should never happen, probably something is wrong with your 
configuration.


----- Original Message ----- 
From: <patric@xxxxxxxxxx>
To: "EclipseLink User Discussions" <eclipselink-users@xxxxxxxxxxx>
Sent: Tuesday, July 28, 2009 11:46 AM
Subject: Re: [eclipselink-users] Removed entity can still be found by 
otherentity manager instances


> Thank you for your answer.
>
> But:
> Interestingly a third EntityManager em3 which has been never used before,
> can also find the removed entity:
>
> //after removal of the entity and commit of em1:
>    assertNull(em1.find(User.class, id));  //no exception, entity is 
> removed!
>    assertNull(em3.find(User.class, id)); //exception! em3 can find  the 
> entity also it was never "found" using this entity manager  instance, 
> hence it should not in its cache
>
> Why? I thought all entities are using a distinct cache
> when using the config parameters as stated below.
>
>
>
> Quoting Andrei Ilitchev <andrei.ilitchev@xxxxxxxxxx>:
>
> > em2.find(User.class, id) adds the object to persistence unit cache;
> > the next time find is called the cached copy is returned.
> >
> > Call em2.refresh(entity) instead of the second find - that throws 
> > EntityNotFoundException.
> >
> > You could also call em.clear() before each find, but that means you 
> > would potentially read each object several times; also could 
> > unintentionally wipe out your changes before they committed.
> > Consider defining the entity with optimistic locking instead, then  you 
> > still can take advantage of caching and exception is thrown on  attempt 
> > to update the object, which no longer exists (or has been  updated by 
> > another app).
> >
> > ----- Original Message ----- From: <patric@xxxxxxxxxx>
> > To: <eclipselink-users@xxxxxxxxxxx>
> > Sent: Tuesday, July 28, 2009 10:56 AM
> > Subject: [eclipselink-users] Removed entity can still be found by  other 
> > entity manager instances
> >
> >
> > > Hello everyone,
> > >
> > > imagine the following situation:
> > >
> > >    User newObj = new User ();
> > >    newObj.setUserMode('A');
> > >    em1.persist(newObj);
> > >    id = newObj.getUserId();
> > >
> > >    assertNull(em2.find(User.class, id)); //no exception, entity can  not 
> > > be found yet.
> > >
> > >    //...committing/beginning transaction of em1 here...
> > >
> > >    assertNotNull(em2.find(User.class, id)); //no exception, entity is 
> > > found
> > >    em1.remove(newObj);
> > >
> > >    //...committing/beginning transaction of em1 here...
> > >
> > >    //after commit of em1:
> > >    assertNull(em1.find(User.class, id));  //no exception, entity is 
> > > removed!
> > >
> > >    assertNull(em2.find(User.class, id)); //exception! em2 can still 
> > > find and access the removed entity!
> > >
> > >
> > >
> > > As you can see, an entity manager can still access a removed entity  (by 
> > > an other entity manager) if it has been fetched before its  removal.
> > >
> > > Even more odd, this entity can be changed without any exceptions  after 
> > > commiting and when looking into the finest logs, entity  manager em2 
> > > seems to execute an update SQL but doesn't check
> > > that no records have updated.
> > >
> > > I would expect at least an exception on this, or even better that  the 
> > > last assertion won't fail already.
> > > How can I archive that?  And how to archive that if an external 
> > > application deletes/modifies a record?
> > >
> > > I tried disabling all caching by setting 
> > > eclipselink.cache.type.default to "NONE", but this didn't help.
> > >
> > > Excerpt from my persistence.xml:
> > >
> > >   <property name="eclipselink.cache.shared.default" value="false"/>
> > >
> > > Best regards,
> > > Patric
> > >
> > >
> > >
> > >
> > > _______________________________________________
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> > > eclipselink-users@xxxxxxxxxxx
> > > https://dev.eclipse.org/mailman/listinfo/eclipselink-users
> >
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>
>
>
>
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