Hi Yasumasa, It all sounds reasonable and of course the impact on downstream tooling vs the value of the change must be evaluated. In this case I think adding a CGC counter makes sense especially in prep for G1 becoming default in 9.
Regards,
Kirk
> On Mar 2, 2016, at 6:58 AM, Yasumasa Suenaga <yasue...@gmail.com> wrote:
>
> Hi Kirk,
>
> Agree to you.
> However, I use occasional FGC counter at CMS as below:
>
> 1. Check major collection occurrence
> Some production systems have large memory as Java heap,
> and they are not set GC log.
> If their CPU usage becomes high, I want to check GC execution.
> (Of course, we have to check any other points :-) )
>
> 2. Core image analysis
> If JVM is crashed, I want to check PerfCounter to know situation.
> (In the past, I sometimes encountered crash at GC worker thread.)
>
> I guess that I will want to check them at G1.
>
> Thus, at least, I want to add PerfCounter for CGC (and add JVMTI event hook).
> However, this proposal will affect to jstat spec.
> So I want to discuss about it before filing to JBS.
>
>
> Thanks,
>
> Yasumasa
>
>
> On 2016/03/02 19:02, k...@kodewerk.com wrote:
>> Hi Yasumasa,
>>
>> Good question. I’ve never considered CMS to be a Full GC. This implies that
>> there should be separate performance counters for CMS pause phases as it is
>> possible to have FGC. Of course a FGC during CMS maybe user triggered,
>> triggered outside a CMS cycle, interrupts a CMS cycle, or interrupts a CMS
>> phase. I’m not sure how much of a distinction one needs to make here as that
>> could be a quick broader discussion. Certainly the purpose isn’t to recreate
>> the GC logs in these performance counters. But at the very least not having
>> a distinction between full and a STW-CMS phase is kind of misleading in my
>> opinion.
>>
>> Regards,
>> Kirk
>>
>>> On Mar 1, 2016, at 5:03 PM, Yasumasa Suenaga <yasue...@gmail.com> wrote:
>>>
>>> Hi Kirk,
>>>
>>>> It is also incorrect to count initial mark and remark in CMS as a FGC.
>>>
>>> Though, how can we check execution of major collection without GC log?
>>> Should we add new PerfCounter for CGC (and add CGC column to jstat output)?
>>>
>>>
>>> Yasumasa
>>>
>>>
>>> On 2016/03/02 6:35, k...@kodewerk.com wrote:
>>>> Hi,
>>>>
>>>> I think it is incorrect to count remark and cleanup as FGC. They are not
>>>> full collections. It is also incorrect to count initial mark and remark in
>>>> CMS as a FGC. It is unfortunate that this is counted this way.
>>>>
>>>> Regards,
>>>> Kirk
>>>>
>>>>> On Mar 1, 2016, at 8:56 AM, Yasumasa Suenaga <yasue...@gmail.com> wrote:
>>>>>
>>>>> Hi all,
>>>>>
>>>>> 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.
>>>>>
>>>>> For consistency, I think that G1 STW phases should be counted as FGC.
>>>>> What do you think about it?
>>>>>
>>>>> If it is accepted, I will file it to JBS and will upload webrev.
>>>>>
>>>>>
>>>>> suggested fix:
>>>>> ----------------------
>>>>> diff -r 8a103ba9a7b2 src/share/vm/gc/g1/g1MonitoringSupport.cpp
>>>>> --- a/src/share/vm/gc/g1/g1MonitoringSupport.cpp Mon Feb 29 22:54:24
>>>>> 2016 +0900
>>>>> +++ b/src/share/vm/gc/g1/g1MonitoringSupport.cpp Tue Mar 01 23:43:30
>>>>> 2016 +0900
>>>>> @@ -103,7 +103,7 @@
>>>>> // name "collector.1". In a generational collector this would be the
>>>>> // old generation collection.
>>>>> _full_collection_counters =
>>>>> - new CollectorCounters("G1 stop-the-world full collections", 1);
>>>>> + new CollectorCounters("G1 stop-the-world phase", 1);
>>>>>
>>>>> // timer sampling for all counters supporting sampling only update the
>>>>> // used value. See the take_sample() method. G1 requires both used and
>>>>> diff -r 8a103ba9a7b2 src/share/vm/gc/g1/vm_operations_g1.cpp
>>>>> --- a/src/share/vm/gc/g1/vm_operations_g1.cpp Mon Feb 29 22:54:24
>>>>> 2016 +0900
>>>>> +++ b/src/share/vm/gc/g1/vm_operations_g1.cpp Tue Mar 01 23:43:30
>>>>> 2016 +0900
>>>>> @@ -230,6 +230,8 @@
>>>>> G1CollectedHeap* g1h = G1CollectedHeap::heap();
>>>>> GCTraceTime(Info, gc) t(_printGCMessage, g1h->gc_timer_cm(),
>>>>> GCCause::_no_gc, true);
>>>>> IsGCActiveMark x;
>>>>> + SvcGCMarker sgcm(SvcGCMarker::OTHER);
>>>>> + TraceCollectorStats tcs(g1h->g1mm()->full_collection_counters());
>>>>> _cl->do_void();
>>>>> }
>>>>>
>>>>> ----------------------
>>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Yasumasa
>>>>>
>>>>>
>>>>
>>
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