RFR: JDK-8151674: STW phases at Concurrent GC should count in PerfCounter

Jon Masamitsu jon.masamitsu at oracle.com
Wed Mar 16 18:13:04 UTC 2016

On 03/10/2016 07:59 PM, Yasumasa Suenaga wrote:
> Hi all,
> This review request continues from:
>    http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2016-March/016774.html
>    http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2016-March/016896.html
> I wonder that STW phases (Remark and Cleanup) at G1 are not counted in jstat FGC column.
> For example, Initial Mark and Remark at CMS are counted as FGC.
> We discussed on hotspot-gc-dev for this issue, and I proposed to add new PerfCounter
> for CGC STW phases.
> I uploaded webrev. Could you review it?
>      hotspot: http://cr.openjdk.java.net/~ysuenaga/JDK-8151674/webrev.00/hotspot/
>          jdk: http://cr.openjdk.java.net/~ysuenaga/JDK-8151674/webrev.00/jdk/
> For compatibility, this patch works the same as the current by default.
> If you set -XX:+EnableConcGCPerfCounter, CGC counter will work fine.
> (I want to set +EnableConcGCPerfCounter by default)

I would prefer not to have the flag (EnableConcGCPerfCounte)
and just make the change for CMS.  This is a change for a major
release and I think we can accept the incompatibility.


+ // name "collector.2". In a generational collector this would be the
+ // STW phases in concurrent collection.
+ _conc_collection_counters =
+ new CollectorCounters("G1 stop-the-world phases", 2);

Is there a hard connection between these phases and a generational
collector (i.e., should the "In a generational collector this would be the"
be dropped in the comment)?

A comment such as

// name "collector.2". STW phases as part of a concurrent collection.

A set of JDK changes had been previously been reviewed (not by me). Are 
the same?



> I cannot access JPRT.
> So I need a sponsor.
> Thanks,
> Yasumasa

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