jsr338-experts@jpa-spec.java.net

[jsr338-experts] Re: clarification needed regarding EntityManager pooling in J2EE environment

From: michael keith <michael.keith_at_oracle.com>
Date: Fri, 11 May 2012 09:22:53 -0400

Hi Christian,

The clear() method was not intended to reinitialize the EM, but is just
a method that causes all of the entities in the persistence context to
be detached. You can actually see an example on page 300 that highlights
this fact. The footnote you reference was just making reference to the
fact that a clear() call would need to be made on the EM in order for it
to be reused. It was not intended to be a complete description of how to
reuse an EM, or of other issues that might also need to be handled. I
admit that it could be a bit misleading, though...

Regards,
-Mike

On 10/05/2012 9:58 AM, Christian Romberg wrote:
> Dear group,
>
> The spec (2.0) says, p.304, section 7.9.1, footnote 79:
>
> "The container may choose to pool EntityManagers: it instead of
> creating and closing in each case, it may acquire one from its pool
> and call clear() on it."
>
> What should happen with any property settings that were changed by the
> user?
> E.g. setFlushMode or any vendor-specific properties?
>
> Should clear() also reset them to the values configured for the
> EntityManagerFactory?
>
> I think this would make sense to get a clean, reusable EntityManager.
>
> And if this is the common understanding of how clear() should work, I
> suggest that we add
> that in the spec.
>
> Thank you!
>
> Christian
>
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> Christian Romberg
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