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

[Andrei Ilitchev <andrei.ilitchev@xxxxxxxxxx>]

Reproduced running out of connections. Please log a bug.

On 12/13/2010 5:39 AM, patric@xxxxxxxxxxx wrote:
> 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
> > _______________________________________________
> > eclipselink-users mailing list
> > eclipselink-users@xxxxxxxxxxx
> > https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>
>
>
>
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