Hi, Prahalad.
Can you please add a stack trace which include a line numbers to the bug
report? Currently it is unclear in what line an exception is occurred.
On 25/10/2017 21:07, Prahalad Kumar Narayanan wrote:
Hello Everyone
Good day to you.
Kindly review a fix for the bug
Bug ID: JDK-8188083
Description: Null Pointer Exception in
java.awt.image.FilteredImageSource.startProduction
Root Cause
. FilteredImageSource implements ImageProducer interface
. All the methods of FilteredImageSource operate on a common data
-HashTable, but only a few are synchronized methods.
. Thus, when synchronized & un-synchronized methods access / modify the
hash table in a multi-threaded scenario, it renders the class vulnerable to this
exception.
Exception occurrence
. The submitter has mentioned that there is no test-case to reproduce to
this issue.
. Luckily I was able to observe this issue with a "crude" test code
. The test triggered 7k threads in an ExecutorService randomly
adding/ removing/ invoking startProduction on FilteredImageSource object.
. I didn't feel it robust enough to be added as a part of regression
tests. I tried optimizing the test but in vain.
. Hence the test code isn't added to the webrev.
Details on the Fix:
. The concerned methods have been "synchronized" in the fix.
. No new regression failures were observed with this change.
Kindly review the change and provide your feedback.
In addition, kindly suggest whether this requires CSR as it adds "synchronized"
to method signature.
Review Link: http://cr.openjdk.java.net/~pnarayanan/8188083/webrev.00/
Thank you for your time in review
Have a good day
Prahalad N.
--
Best regards, Sergey.
