Re: [eclipselink-users] EclipseLink lockup in exclusive isolated session

[patric@xxxxxxxxxxx]

Hi Andrei,

thank you for helping me.
Please adjust the testcase to reproduce the bug:

     public void testExclusiveSessionRunOutOfConnections() {
         EntityManager em = createEntityManager("customfeatures");

         //because a change/(bug?) in EL 2.1, it's important to set  
the pool name to null
         //that EL will really disable internal connection pooling
         ((ClientSession) ((EntityManagerImpl) em).getUnitOfWork()
         .getParent()).getConnectionPolicy().setPoolName(null);

         boolean loop = true;
         while(loop) {
             em.clear(); // it's important that clear() is invoked  
"between" a transaction
             beginTransaction(em);
 //            Employee emp = em.find(Employee.class, 1);
 //            List<Employee> employees = em.createQuery("SELECT
 OBJECT(e) FROM Employee e").getResultList();
             List names = em.createNativeQuery("SELECT NAME FROM
 CUSTOM_FEATURE_EMPLOYEE").getResultList();
             commitTransaction(em);
         }
     }



Best regards,
Patric


Zitat von Andrei Ilitchev <andrei.ilitchev@xxxxxxxxxx>:

> I can't reproduce running out of connections:
>
> persistence.xml:
>
> <persistence xmlns="http://java.sun.com/xml/ns/persistence";  
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";  
> xsi:schemaLocation="http://java.sun.com/xml/ns/persistence  
> persistence_1_0.xsd" version="1.0">
>     <persistence-unit name="customfeatures"  
> transaction-type="RESOURCE_LOCAL">
>
> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
>
> <class>org.eclipse.persistence.testing.models.jpa.customfeatures.Employee</class>
>         <properties>
>             <property name="eclipselink.session.customizer"  
> value="org.eclipse.persistence.testing.models.jpa.customfeatures.Customizer"/>
>             <property  
> name="eclipselink.jdbc.exclusive-connection.mode" value="Always"/>
>         </properties>
>     </persistence-unit>
>
> </persistence>
>
>
> The testing framework I am using passes user/password/url to  
> createEntityManagerFactory method.
> I am creating a data source in customizer:
> public class Customizer implements SessionCustomizer {
>     public void customize(Session session) throws SQLException {
>         OracleDataSource ds = new OracleDataSource();
>         ds.setURL(session.getLogin().getConnectionString());
>         session.getLogin().setConnector(new JNDIConnector(ds));
>         session.getLogin().useExternalConnectionPooling();
>     }
> }
>
> The test runs forever using the same connection all the time no  
> matter is it find, query or native query.
>     public void testExclusiveSessionRunOutOfConnections() {
>         EntityManager em = createEntityManager("customfeatures");
>         boolean loop = true;
>         while(loop) {
>             beginTransaction(em);
> //            Employee emp = em.find(Employee.class, 1);
> //            List<Employee> employees = em.createQuery("SELECT  
> OBJECT(e) FROM Employee e").getResultList();
>             List names = em.createNativeQuery("SELECT NAME FROM  
> CUSTOM_FEATURE_EMPLOYEE").getResultList();
>             commitTransaction(em);
>         }
>     }
>
> > And I've got another question: will EntityManager.close() release/close
> > the acquired connection in the exclusive isolated mode?
> Yes.
>
> On 12/9/2010 9:27 AM, patric@xxxxxxxxxxx wrote:
> > Hello,
> >
> > I am experiencing a critical issue when using the exclusive isolated
> > session mode which results in a lockup during a database call.
> >
> > To reproduce it, do the following:
> >
> > 1. Enable exclusive isolated session mode (property
> > eclipselink.jdbc.exclusive-connection.mode = Always) and use the
> > external connection pool mode
> > 2. Use a non-JTA Datasource
> > 3. Begin EntityManager transaction
> > 4. Do a JPA Operation (e.g. find())
> > 5. Commit the EntityManager transaction
> > 6. Repeat steps 3-5 several times (ca. 50)
> > => database call will lock.
> >
> > I investigated this issue and it seems that a EntityManager transaction
> > commit will not release the connection hold by the exclusive isolated
> > client session (which is fine and expected).
> > But, due to the "resetted" transaction it will acquire a new one than
> > re-using the acquired one.
> >
> > After some iterations, maxNumberOfNonPooledConnections will be exceeded,
> > which will end up that the ServerSession will wait forever for obtaining
> > a new connection in the wait() call.
> >
> > Here's the stacktrace for the issue:
> > Thread [Thread-3] (Suspended)
> > waiting for: ServerSession (id=313)
> > Object.wait(long) line: not available [native method]
> > ServerSession(Object).wait() line: 474
> > ServerSession.acquireClientConnection(ClientSession) line: 268
> > ExclusiveIsolatedClientSession(ClientSession).basicBeginTransaction()
> > line: 123
> > ExclusiveIsolatedClientSession(AbstractSession).beginTransaction() line:
> > 552
> > RepeatableWriteUnitOfWork(UnitOfWorkImpl).beginTransaction() line: 509
> > RepeatableWriteUnitOfWork(UnitOfWorkImpl).beginEarlyTransaction() line: 499
> > EJBQueryImpl.executeReadQuery() line: 383
> > EJBQueryImpl.getResultList() line: 568
> > ...
> >
> > And I've got another question: will EntityManager.close() release/close
> > the acquired connection in the exclusive isolated mode?
> >
> >
> > I really appreciate your help.
> >
> > Best regards,
> > Patric
> >
> >
> > _______________________________________________
> > eclipselink-users mailing list
> > eclipselink-users@xxxxxxxxxxx
> > https://dev.eclipse.org/mailman/listinfo/eclipselink-users
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