<AWT Dev> <Swing Dev> EventQueue NPE?

Alexander Scherbatiy alexandr.scherbatiy at oracle.com
Wed Feb 19 01:09:03 PST 2014

On 2/19/2014 8:03 AM, Keith Amling wrote:
> I may be barking up the wrong tree e-mailing an OpenJDK list when I've
> only reproduced this against an Oracle JDK (1.7.0_25, and in particular
> it doesn't reproduce against 1.7.0_21), but the attached file produces
> NPEs [1] via EventQueue.isDispatchThread() fairly regularly with an
> argument of 10 [threads] and can even produce it with just 2 (although
> less often).
     This is an interesting exception. I am able to reproduce it with 
the JDK 7u51 but
     not able to reproduce it with the JDK 8.

    Could you check that the issue is not reproduced on your side with 
the latest JDK 8:

> We've had even weirder NPEs [2] in the code behind that but I have yet
> to distill them to a repro unfortunately.
     We have several reports about this NPE like:

     It should have been already fixed in JDK 7u60 and in the JDK 8.

> Are either of these known?  Is there something we should be doing in our
> rather multi-threaded environment to protect this code?
> Keith
> [1] E.g.:
>> java.lang.NullPointerException
>> 	at java.awt.EventQueue.isDispatchThread(EventQueue.java:1014)
>> 	at EQNPE$1.run(EQNPE.java:23)
> [2] Ending in:
>> java.lang.NullPointerException
>> 	at sun.awt.SunToolkit.getSystemEventQueueImplPP(SunToolkit.java:1011)
>> 	at sun.awt.SunToolkit.getSystemEventQueueImplPP(SunToolkit.java:1007)
>> 	at sun.awt.HeadlessToolkit.getSystemEventQueueImpl(HeadlessToolkit.java:352)
>> 	at java.awt.Toolkit.getSystemEventQueue(Toolkit.java:1717)
>> 	<our code>

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