RFR(XS) Contended Locking speedup PlatformEvent unpark bucket (8061552)

[David Holmes]

Thanks for clarifying things Dan.

Good to go.

David

On 29/10/2014 2:09 AM, Daniel D. Daugherty wrote:
> On 10/28/14 1:33 AM, David Holmes wrote:
>> Hi Dan,
>
> David, Thanks for the review!
>
>
>> On 28/10/2014 8:34 AM, Daniel D. Daugherty wrote:
>>> Greetings,
>>>
>>> I have the Contended Locking speedup PlatformEvent unpark bucket
>>> ready for review. These are small comment only changes that have
>>> already been reviewed by Karen Kinnear (acorn) and Dave Dice (dice).
>>> It would be good to get one or two more pair of eyes on these
>>> comment additions/updates/synchronizations.
>>
>> So there's a bit of cross-platform inconsistency. For example you
>> deleted the TO-DO/FIXME chunk of comments on Solaris but left them on
>> Windows. Granted parts are different (and my not be true/relevant any
>> more) but parts are basically the same eg:
>>
>> -  Reconcile Doug's JSR166 j.u.c park-unpark with the objectmonitor
>> implementation.
>>
>> -  Collapse the JSR166 parker event, and the objectmonitor ParkEvent
>> into a single "Event" construct.
>
> You're right about this deletion inconsistency. I didn't finish
> running down the details about this particular deletion. I have
> to chase that down with Dave Dice and Karen Kinnear and that will
> take some time so it won't be done as part of this fix.
>
>
>
>> Also linux/bsd have the transition information only in the park/unpark
>> functions, but solaris and windows have it both in the functions and
>> as part of the preeamble - which seems redundant to me.
>
> Solaris and Windows have a big introductory comment that is similar,
> but not the same between those two platforms. Linux has a reference
> to the Solaris introductory comment:
>
> 5404 // Refer to the comments in os_solaris.cpp park-unpark.
>
> and BSD inherited that reference comment from Linux...
>
> We're trying to figure out the best way to reconcile this type of
> common introductory comment, but that will be handled separately.
> I'm discussing the issue with Jerry Thornbrugh as part of his *NIX
> work and with both Dave Dice and Karen Kinnear to make sure that
> we don't lose anything important.
>
>
>> Also os_aix.cpp is missing, but is presumably similar to the linux/bsd
>> cases.
>
> AIX is actually missing many of the bug fixes from 2012.12/2013.01
> bug_fix bucket work. It looks like the AIX project based their work
> on earlier versions of os_linux.cpp, but didn't keep track of the
> changes to os_linux.cpp afterward... Our plan is to go through all
> of the bugs associated with this project and file new AIX specific
> bugs for fixes that are missing.
>
> Thanks again for the review!
>
> Dan
>
>
>>
>> Cheers,
>> David
>>
>>> Historial reminder:
>>>
>>>      Back in 2012.12 and 2013.01, work on the "bug fix bucket" for the
>>>      Contended Locking project was being done. One of the bug fixes was:
>>>
>>>      JDK-8004902 correctness fixes motivated by contended locking work
>>> (6607129)
>>>      https://bugs.openjdk.java.net/browse/JDK-8004902
>>>
>>>      The work on JDK-8004902 picked up all of the code changes and
>>> many of
>>>      comments that were part of this bucket (speedup PlatformEvent
>>> unpark).
>>>
>>>      Here's the webrev for "bug fix bucket":
>>>
>>> http://cr.openjdk.java.net/~dcubed/cl_bug_fix_bucket-webrev/2/
>>>
>>>      The bug fix bucket included fixes for 6444286, 8004902 and 8004903,
>>>      but the majority of the work was done for 8004902. Now back to the
>>>      current thread...
>>>
>>> This work is being tracked by the following bug ID:
>>>
>>>      JDK-8061552 Contended Locking speedup PlatformEvent unpark bucket
>>>      https://bugs.openjdk.java.net/browse/JDK-8061552
>>>
>>> Here is the webrev URL:
>>>
>>> http://cr.openjdk.java.net/~dcubed/8061552-webrev/2-jdk9-hs-rt/
>>>
>>> Here is the JEP link:
>>>
>>>      https://bugs.openjdk.java.net/browse/JDK-8046133
>>>
>>> Testing:
>>>
>>> - JPRT test jobs
>