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Re: [eclipselink-users] Removed entity can still be found by other entity manager instances
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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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