(Reposted from Users forum)....

Hi,
I am doing some experimentation with Hibernate and EJB3 and have noticed if I run a simple query using entityManager.createQuery() it is several times slower than a standard hibernate session.createQuery() executing the same query string.

I am timing the actual hibernate call itself (not serialisation etc.) so i can't explain the differences....
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long starMillis = System.currentTimeMillis();
List<Job> temp = entityManager.createQuery("from JobBean WHERE completionDate IS NULL AND isClosed = false AND deleted = false ORDER BY id").getResultList();
long endMillis = System.currentTimeMillis();

log.info("Adding " + temp.size() + " jobs in " + (endMillis-starMillis) + "mS");
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and

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long starMillis = System.currentTimeMillis();
List<Job> temp = session.createQuery("from JobBean WHERE completionDate IS NULL AND isClosed = false AND deleted = false ORDER BY id").getResultList();
long endMillis = System.currentTimeMillis();

log.info("Adding " + temp.size() + " jobs in " + (endMillis-starMillis) + "mS");
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The EJB is running in GlassfishV2 and the hibernate session version is running in a JSE application. The PU and hibernate.cfg.xml have the same parameters etc..

The Session bean/EntityManager takes 24 seconds to retrieve 3216 jobs and the standard JSE/session takes a mere 6.7 seconds - so the difference is nontrivial.

The only other change asside from the EntityManager Vs raw hibernate session is the EntityManager entities utilise interfaces and make use of the @Target(class) annotation to identify the implementation class - asside from that the models are the same.

Still confused as to what is causing the performance problem....

Any help and pointers appreciated.

Has anyone experienced anything similar?

1) could you try removing the @Target to make them really the same?

2)are you sure the same transactions are used?

OK, I haven't removed the @Target annotation yet, cos thats a lot of work... but I created a standard hibernate session within the EJB, so know I run the same query via the app server managed EntityManager and via a hibernate session created from a standalone hiberbate.cfg.xml....


EntityManager query time = 26.6 seconds
Hibernate session query time = 12.3 seconds

So, they are both slower than the same code run in JSE, and the EntityManager is still considerably slower than a standard hibernate session.

Still more investigation needed