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https://issues.apache.org/jira/browse/OPENJPA-1516?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kevin Sutter updated OPENJPA-1516:
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Attachment: openjpa-1516.2.patch
Updated patch with thread locking...
> Introduce new "clear" method on EntityManagerImpl
> -------------------------------------------------
>
> Key: OPENJPA-1516
> URL: https://issues.apache.org/jira/browse/OPENJPA-1516
> Project: OpenJPA
> Issue Type: Improvement
> Components: integration
> Affects Versions: 2.0.0-beta
> Reporter: Kevin Sutter
> Assignee: Kevin Sutter
> Fix For: 2.0.0
>
> Attachments: openjpa-1516.2.patch, openjpa-1516.patch
>
>
> Per the JPA specification, EntityManagers are allowed to be pooled by the
> container by calling the clear() method. This clear() processing is more
> efficient than closing the EM and re-creating it with every
> PersistenceContext injection. This is working for the most part.
> But, there are use cases where the defined clear() processing is not
> sufficient. We have run into customer situations where the connection is
> still active when the EM gets pooled. And, when this EM gets handed out to
> another thread/transaction, strange errors and exceptions can occur due to
> the active connection. The JPA specification and the javadoc for EM.clear()
> doesn't say anything about closing out resources (connections) like the
> close() documentation does.
> But, the spec does allow for more efficient processing between the container
> and the jpa provider (instead of relying on the clear() method) per this
> footnote:
> [78] It is not required that these contracts be used when a third-party
> persistence provider is not used: the container might use these
> same APIs or its might use its own internal APIs.
> In order to open the door for more efficient and more complete "clear"
> processing before pooling an OpenJPA EntityManager, this JIRA is introducing
> a new method on our EntityManagerImpl called prepareForPooling(). Since this
> is for very specific usage, I don't want to put this on the
> OpenJPAEntityManager interface. Also, I have raised this as a concern with
> the JPA Expert Group and an alternative solution might be proposed in a
> future revision of the spec. Containers that wish to take advantage of this
> can very easily detect the existence of this method and call
> prepareForPooling() instead of the clear().
> Due to the customer situation, I would like to get this committed yet this
> week. Please raise any concerns with this approach immediately. Thanks!
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