[jira] Resolved: (OPENJPA-368) Multithreaded client fails randomly on EntityManager.persist() with out transaction context.

["Patrick Linskey (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/OPENJPA-368?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Patrick Linskey resolved OPENJPA-368.
-------------------------------------

       Resolution: Fixed
    Fix Version/s: 1.1.0
                   1.0.1

Committing Vikram's patch. FTR, I don't love the fact that we're using a ThreadLocal; it feels wrong. However, given the current API design, I think it's unavoidable. Once we move to a system that provides a means to execute a Runnable or some analog in an out-of-band transaction via the ManagedRuntime interface, we'll be able to simplify this code.

> Multithreaded client fails randomly on EntityManager.persist() with out transaction context.
> --------------------------------------------------------------------------------------------
>
>                 Key: OPENJPA-368
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-368
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: jdbc
>    Affects Versions: 0.9.7, 1.0.0
>         Environment: WebLogic Server 10.0, Oracle DB
>            Reporter: Vikram Bhatia
>             Fix For: 1.0.1, 1.1.0
>
>         Attachments: proposed-fix-v2.patch, proposed-fix.patch, testcase.zip
>
>
> This issue happens with the following scenario with JTA transaction.
> Suppose there is Entity A which is related to table with two columns accountId and name. accountId is PK of the table whose value is generated using sequence in DB.
> 1. Thread A starts Transaction 1.
> 2. Thread B starts Transaction 2.
> 3. Thread A and Thread B both calls EntityManager.persist(o) where o is 
> Entity object whose primary key is generated with a sequence in DB.
> 4. A call is made to o.getAccountId() concurrently.
> 5. Thread A suspends Transaction 1, and gets the value of accountId. It updates 
> sequence value in DB with new Transaction 3. It saves Transaction 1.
> 6. Thread B suspends Transaction 2, and gets the value of accountId. It updates 
> sequence value in DB with new Transaction 4. It saves Transaction 2.
> 7. Now, when both Thread A and Thread B resumes outer transaction 
> concurrently, it updates Transaction Manager with Transaction 2.
> The problem happens when JTA transaction is saved in AbstractJDBCSeq _outerTransaction variable. The variable gets overwritten if multiple threads load the value of accountId from sequence in DB, when it resumes the JTA transaction later it resumes the transaction 2 for both threads resulting in following exception.
> javax.ejb.EJBException: nested exception is: javax.persistence.TransactionRequiredException: The method public abstract void javax.persistence.EntityManager.persist(java.lang.Object) must be called in the context of a transaction.
> javax.persistence.TransactionRequiredException: The method public abstract void javax.persistence.EntityManager.persist(java.lang.Object) must be called in the context of a transaction.
> 	at weblogic.deployment.BasePersistenceContextProxyImpl.validateInvocation(BasePersistenceContextProxyImpl.java:121)
> 	at weblogic.deployment.BasePersistenceContextProxyImpl.invoke(BasePersistenceContextProxyImpl.java:86)
> 	at weblogic.deployment.TransactionalEntityManagerProxyImpl.invoke(TransactionalEntityManagerProxyImpl.java:90)
> 	at weblogic.deployment.BasePersistenceContextProxyImpl.invoke(BasePersistenceContextProxyImpl.java:80)
> 	at $Proxy63.persist(Unknown Source)
> Please check README.txt of attached testcase.zip to see how to reproduce the issue.

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