Eclipse Community Forums: EMF » [CDO] Problem with concurrent read and write threads

Help

Home

Home » Modeling » EMF » [CDO] Problem with concurrent read and write threads

Show: Today's Messages :: Show Polls :: Message Navigator

[CDO] Problem with concurrent read and write threads [message #987716]

Tue, 27 November 2012 17:29

Silvestre Martins

Messages: 84
Registered: July 2009

Member

I'm noticing a very strange behavior in the following test I made using concurrent access.
Scenario: I have 2 threads, 1 reader and 1 writer, executing concurrently. We never have write conflicts, because we have only 1 writer.
The threads are executing without any delay, because I want to see how CDO handles many requests. For each iteration, a new session is created.
During the test I get some exceptions (NPE). If I don't make the commit then there isn't any exception.

!ENTRY org.eclipse.net4j 4 0 2012-11-27 16:31:14.217
!MESSAGE NullPointerException
!STACK 0
java.lang.NullPointerException
	at org.eclipse.emf.cdo.spi.common.protocol.CDODataInputImpl.readCDOBranch(CDODataInputImpl.java:188)
	at org.eclipse.emf.cdo.spi.common.protocol.CDODataInputImpl.readCDOCommitInfo(CDODataInputImpl.java:276)
	at org.eclipse.emf.cdo.internal.net4j.protocol.CommitNotificationIndication.indicating(CommitNotificationIndication.java:36)
	at org.eclipse.emf.cdo.internal.net4j.protocol.CDOClientIndication.indicating(CDOClientIndication.java:56)
	at org.eclipse.net4j.signal.Indication.doExtendedInput(Indication.java:57)
	at org.eclipse.net4j.signal.Signal.doInput(Signal.java:328)
	at org.eclipse.net4j.signal.Indication.execute(Indication.java:51)
	at org.eclipse.net4j.signal.Signal.runSync(Signal.java:253)
	at org.eclipse.net4j.signal.Signal.run(Signal.java:149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:662)

I checked and the writes didn't failed, everything was persisted.
Is this an "expected" behavior (let's say, a known limitation) when opening and closing so many CDOSession in a very short time? Or can we say it is a bug?
I attached the test java file.

Attachment: TestCDOConcurrency.java
(Size: 3.80KB, Downloaded 132 times)

Report message to a moderator

Re: [CDO] Problem with concurrent read and write threads [message #987770 is a reply to message #987716]

Wed, 28 November 2012 04:06

Eike Stepper

Messages: 6682
Registered: July 2009

Senior Member

Am 27.11.2012 18:29, schrieb Silvestre Martins:
> I'm noticing a very strange behavior in the following test I made using concurrent access.
> Scenario: I have 2 threads, 1 reader and 1 writer, executing concurrently. We never have write conflicts, because we have only 1 writer.
> The threads are executing without any delay, because I want to see how CDO handles many requests. For each iteration, a new session is created.
> During the test I get some exceptions (NPE). If I don't make the commit then there isn't any exception.
>
> !ENTRY org.eclipse.net4j 4 0 2012-11-27 16:31:14.217
> !MESSAGE NullPointerException
> !STACK 0
> java.lang.NullPointerException
> at org.eclipse.emf.cdo.spi.common.protocol.CDODataInputImpl.readCDOBranch(CDODataInputImpl.java:188)
> at org.eclipse.emf.cdo.spi.common.protocol.CDODataInputImpl.readCDOCommitInfo(CDODataInputImpl.java:276)
> at org.eclipse.emf.cdo.internal.net4j.protocol.CommitNotificationIndication.indicating(CommitNotificationIndication.java:36)
> at org.eclipse.emf.cdo.internal.net4j.protocol.CDOClientIndication.indicating(CDOClientIndication.java:56)
> at org.eclipse.net4j.signal.Indication.doExtendedInput(Indication.java:57)
> at org.eclipse.net4j.signal.Signal.doInput(Signal.java:328)
> at org.eclipse.net4j.signal.Indication.execute(Indication.java:51)
> at org.eclipse.net4j.signal.Signal.runSync(Signal.java:253)
> at org.eclipse.net4j.signal.Signal.run(Signal.java:149)
> at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:662)
>
> I checked and the writes didn't failed, everything was persisted.
> Is this an "expected" behavior (let's say, a known limitation) when opening and closing so many CDOSession in a very short time? Or can we say it is a bug?
> I attached the test java file.
Looks like a duplicate of your other post.
Cheers
/Eike

----
http://www.esc-net.de
http://thegordian.blogspot.com
http://twitter.com/eikestepper

Cheers
/Eike

----
http://www.esc-net.de
http://thegordian.blogspot.com
http://twitter.com/eikestepper

Report message to a moderator