RFR(XXS): 8077392 and 8131715 - fix for hang in Contended Locking "fast enter" bucket

[Vladimir Kozlov]

On 3/24/16 12:23 PM, David Holmes wrote:
> Hi Dan,
>
> Couldn't pass up the chance to review this - truly great debugging here!

+1

Changes are good.

Thanks,
Vladimir

>
> The changes of course look good.
>
> I was surprised to notice that before this fix the Lock argument (which should be lower-case lock if you don't mind
> adjusting that) was actually unused in quick_enter! So one has to wonder why it was passed in.
>
> Cheers,
> David
>
>
>
> On 23/03/2016 6:41 AM, Daniel D. Daugherty wrote:
>> Greetings,
>>
>> I have fixes for the following two bugs:
>>
>>      JDK-8077392 Stream fork/join tasks occasionally fail to complete
>>      https://bugs.openjdk.java.net/browse/JDK-8077392
>>
>>      JDK-8131715 backout the fix for JDK-8079359 when JDK-8077392 is fixed
>>      https://bugs.openjdk.java.net/browse/JDK-8131715
>>
>> Both fixes are very, very small and will be bundled together in the
>> same changeset for obvious reasons.
>>
>> Here is the webrev URL:
>>
>> http://cr.openjdk.java.net/~dcubed/8077392_8131715-webrev/0-jdk9-hs-rt/
>>
>> While the fix for JDK-8077392 is a simple 1-liner, the explanation of
>> the race is much, much longer. I've attached the detailed evaluation
>> to this RFR; it is a copy of the same note that I added to
>> https://bugs.openjdk.java.net/browse/JDK-8077392, but the attached
>> copy has all the indentation white space intact. I don't know why
>> JBS likes to reformat the notes, but it does... :-(
>>
>> Testing:
>>
>> - the original failing test is running in a parallel stress config
>>    on my Solaris X64 server; just under 23 hours and just under
>>    3000 iterations without a failure in either instance; I'm planning
>>    to let the stress run go for at least 72 hours.
>> - RT/SVC nightly equivalent (in progress)
>>
>> As always, comments, suggestions and/or questions are welcome.
>>
>> Dan