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https://issues.apache.org/jira/browse/OPENJPA-739?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12637937#action_12637937
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Michael Dick commented on OPENJPA-739:
--------------------------------------
EntityManagerFactories are (or need to be) thread safe (EMs are not). It would
be interesting to see if the problem only occurs when you use the subclassing
support though. Sadly the subclassing support yields very different behavior
from the "normal" enhancement path. So when we see it in the stack we tend to
run the PCEnhancer first to eliminate it as a possibility.
The questions about the feature pack were just to make sure there were no
conflicts with the version of OpenJPA that ships with the feature pack.
I suspect that using build time enhancement will resolve the problem, but may
not be permanent solution. The subclassing support is re-reading the metadata
for your entities - it's this scan of the meta data that apparently isn't
thread safe. Can you try using the PCEnhancer and seeing if that does resolve
the issue?
> Multi thread calls to EntityManagerFactory.getEntityManager() results in
> org.apache.openjpa.persistence.ArgumentException
> -------------------------------------------------------------------------------------------------------------------------
>
> Key: OPENJPA-739
> URL: https://issues.apache.org/jira/browse/OPENJPA-739
> Project: OpenJPA
> Issue Type: Bug
> Affects Versions: 1.1.0
> Environment: OS->Windows XP SP2
> App Server-> IBM Websphere App Server v6.1.0.13
> JDK-> IBM JDK v1.5
> JPA-> release 1.1.0
> Reporter: Sachin Deshpande
> Priority: Critical
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> Multi thread calls to EntityManagerFactory.getEntityManager() results in
> <openjpa-1.1.0-r422266:657916 fatal user error>
> org.apache.openjpa.persistence.ArgumentException: Field
> "*.*.*.entity.Rtlr.consCollection" declares "*.*.*.entity.Cons.rtlrCd" as its
> mapped-by field, but this field is not a direct relation.
> at
> org.apache.openjpa.jdbc.meta.strats.RelationToManyInverseKeyFieldStrategy.map(RelationToManyInverseKeyFieldStrategy.java:126)
> at
> org.apache.openjpa.jdbc.meta.strats.RelationCollectionInverseKeyFieldStrategy.map(RelationCollectionInverseKeyFieldStrategy.java:95)
> at
> org.apache.openjpa.jdbc.meta.FieldMapping.setStrategy(FieldMapping.java:120)
> at
> org.apache.openjpa.jdbc.meta.RuntimeStrategyInstaller.installStrategy(RuntimeStrategyInstaller.java:80)
> at
> org.apache.openjpa.jdbc.meta.FieldMapping.resolveMapping(FieldMapping.java:438)
> at
> org.apache.openjpa.jdbc.meta.FieldMapping.resolve(FieldMapping.java:403)
> at
> org.apache.openjpa.jdbc.meta.ClassMapping.resolveMapping(ClassMapping.java:812)
> at
> org.apache.openjpa.meta.ClassMetaData.resolve(ClassMetaData.java:1625)
> at
> org.apache.openjpa.meta.MetaDataRepository.processBuffer(MetaDataRepository.java:717)
> at
> org.apache.openjpa.meta.MetaDataRepository.resolveMapping(MetaDataRepository.java:677)
> at
> org.apache.openjpa.meta.MetaDataRepository.resolve(MetaDataRepository.java:555)
> at
> org.apache.openjpa.meta.MetaDataRepository.getMetaData(MetaDataRepository.java:308)
> at org.apache.openjpa.enhance.PCEnhancer.<init>(PCEnhancer.java:248)
> at org.apache.openjpa.enhance.PCEnhancer.<init>(PCEnhancer.java:219)
> at org.apache.openjpa.enhance.PCEnhancer.<init>(PCEnhancer.java:187)
> at
> org.apache.openjpa.enhance.ManagedClassSubclasser.prepareUnenhancedClasses(ManagedClassSubclasser.java:121)
> at
> org.apache.openjpa.kernel.AbstractBrokerFactory.loadPersistentTypes(AbstractBrokerFactory.java:310)
> at
> org.apache.openjpa.kernel.AbstractBrokerFactory.initializeBroker(AbstractBrokerFactory.java:228)
> at
> org.apache.openjpa.kernel.AbstractBrokerFactory.newBroker(AbstractBrokerFactory.java:190)
> at
> org.apache.openjpa.kernel.DelegatingBrokerFactory.newBroker(DelegatingBrokerFactory.java:142)
> at
> org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:192)
> at
> org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:145)
> at
> org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:56)
> at *.*.*.utility.DBUtilities.getEntityManager(DBUtilities.java:20)
> ...
> ...
> ...
> To access all EntityManagers we have the following custom class:
> public class DBUtilities {
> private static EntityManagerFactory emf = null;
>
> static {
> CommonResources resource = CommonResources.getInstance();
> String env = resource.getValue("jndi.persistanceUnit.use");
> emf = Persistence.createEntityManagerFactory(env);
> }
>
> /**
> * Return Entity Manager
> * @return
> */
> public static EntityManager getEntityManager() {
> return emf.createEntityManager();
> }
> }
> The code is supposed to run in a multi-threaded environment where
> parallel threads invoke DBUtilities.getEntityManager() method. In such a
> scenario, we get the above exception.
> However, if we 'synchronize' the DBUtilities's getEntityManager()
> method, the exception does not occur and the code executes successfully.
> This is contrary to our understanding that EntityManagerFactory is
> thread safe and EntityManagerFactory's .createEntityManager() method creates
> a new instance of EntityManager everytime though being invoked by multiple
> threads.
> Please advice.
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