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https://issues.apache.org/jira/browse/OPENJPA-1716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13423118#comment-13423118
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Albert Lee commented on OPENJPA-1716:
-------------------------------------
The JPA spec is very explicit on thread safety. I.e. EntityManagerFactory is
thread-safe but EntityManager is NOT. There are many examples in the spec
illustrate how to handle the condition using applicaton managed persistence
context.
I am not familar with the details of Apache Servicemix and Aries Blueprint. Is
it a JEE compliant JPA container? If so, the injected contained-managed
EntityManager should handle multi-thread call to the JEE component. The
injected em is typically not the real entity manager but a proxy based on
transaction context for handling context propagation in the JEE container. This
feature is defined in the JPA spec.
Application should not rely on JPA provider non-standard feature
(multi-thread=true) to overcome application specific requirement. Otherwise the
application will not be portable to other JPA provider and may be error-prone.
> Deadlock with openjpa.Multithreaded=true
> ----------------------------------------
>
> Key: OPENJPA-1716
> URL: https://issues.apache.org/jira/browse/OPENJPA-1716
> Project: OpenJPA
> Issue Type: Bug
> Affects Versions: 2.0.0-M1, 2.0.0-M2, 2.0.0-M3, 2.0.0-beta, 2.0.0-beta2,
> 2.0.0-beta3, 2.0.0
> Reporter: Stefan Wokusch
> Assignee: Rick Curtis
> Attachments: OPENJPA-1716.PATCH
>
>
> There is a Deadlock by using Multithreaded=true and work with some Threads on
> the same Entitymanager.
> After many hours of debugging, i found a solution for that Deadlock: The
> Problem could be solved by adding another lock into the lock Method of the
> StateManagerImpl:
> StateManagerImpl ~line3308
> /**
> * Lock the state manager if the multithreaded option is set.
> */
> protected void lock() {
> if (_instanceLock != null){
> _broker.lock();//<- This is the new Part to fix the Deadlock
> _instanceLock.lock();
> }
> }
> Worked for me without Problems for a long time.
> Some other Configurations:
> <persistence xmlns="http://java.sun.com/xml/ns/persistence";
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; version="1.0">
> <persistence-unit name="default" transaction-type="RESOURCE_LOCAL">
> <mapping-file>orm.xml</mapping-file>
>
> <class>...</class>
> <class>...</class>
>
> <properties>
> <property name="openjpa.OrphanedKeyAction"
> value="log(Channel=Orphans, Level=TRACE)" />
> <property name="openjpa.ConnectionFactoryProperties"
> value="PrettyPrint=true, PrettyPrintLineLength=80" />
> <property name="openjpa.Multithreaded" value="true" />
> <property name="openjpa.InverseManager" value="true" />
> <property name="openjpa.LockManager" value="none" />
> <property name="openjpa.WriteLockLevel" value="none" />
> <property name="openjpa.Compatibility" value="
> QuotedNumbersInQueries=true,
> CopyOnDetach=true,
> cascadeWithDetach=true,
>
> superclassDiscriminatorStrategyByDefault=false
> " />
> <property name="openjpa.DetachState"
> value="fetch-groups" />
> <property name="openjpa.jdbc.SynchronizeMappings"
> value="buildSchema" />
> <!-- Default DataSource -->
> <property name="openjpa.ConnectionURL"
> value="jdbc:h2:db/test" />
> <property name="openjpa.ConnectionDriverName"
> value="org.h2.Driver" />
> </properties>
> </persistence-unit>
> </persistence>
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