[wildfly-dev] Call For Help (Testsuite)

[Andrig Miller]

I recently help out on a customer case, which came from the Linux side of the house, which had to do with Java when virtualized.  The customer produced a test case that was emulating the application where the performance slowdown was occuring.  It turned out that they were using ReentrantReadWriteLock for some synchronization.  I did some thread dumps of the test case, and looked at the source too, and found out that ReentrantReadWriteLock was using the ...Unsafe.park() native method, which does a futex() system call.  That system call has terrible performance when virtualized, compared to using ReentrantLock, which has been changed with JDK 7 to no longer depend on the native code, and does everything in Java, in user space.  Performance was so much better, and with some vitualization configuration settings was almost equal to bare metal performance.

That's a long story, just to say, if we have intermittent test suite failures only when run virtualized, perhaps we have some Java code that is using native code that calls futex() in the OS.  If so, it will perform very poorly compared to bare metal, and could be part of the problem with intermittent test failures, especially if there are any timing issues in the test cases.

Just an FYI for something to look out for.

Andy

----- Original Message -----
> From: "Jason Greene" <jason.greene at redhat.com>
> To: wildfly-dev at lists.jboss.org
> Sent: Wednesday, June 12, 2013 1:01:10 PM
> Subject: [wildfly-dev] Call For Help (Testsuite)
> 
> We still have a number intermittent test failures that have been
> around for over a year now. I'm asking for everyone's help in doing
> what we can to make them stable. If you submit a PR, and you see
> what looks like an intermittent failure, can you do some
> investigation and report your findings even if it is not your area?
> It would be awesome if you can report what you find to the mailing
> list, and rope in help.
> 
> Nearly all of these seem to only occur when virtualization is
> involved, so if need be we can work out a plan to create either a
> special run to capture diagnostic info, or I can give access to a
> dedicated slave.
> 
> If anyone has any further ideas on how to tackle these issues I am
> all ears.
> 
> --
> Jason T. Greene
> WildFly Lead / JBoss EAP Platform Architect
> JBoss, a division of Red Hat
> 
> 
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