[eclipselink-users] EclipseLink lockup in exclusive isolated session mod

[patric@xxxxxxxxxxx]

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