G1 STW phases and FGC column in jstat (original) (raw)

Yasumasa Suenaga yasuenag at gmail.com
Tue Mar 1 23:03:34 UTC 2016

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, kirk at 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 <yasuenag at 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. fullcollectioncounters = - 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 takesample() method. G1 requires both used and diff -r 8a103ba9a7b2 src/share/vm/gc/g1/vmoperationsg1.cpp --- a/src/share/vm/gc/g1/vmoperationsg1.cpp Mon Feb 29 22:54:24 2016 +0900 +++ b/src/share/vm/gc/g1/vmoperationsg1.cpp Tue Mar 01 23:43:30 2016 +0900 @@ -230,6 +230,8 @@ G1CollectedHeap* g1h = G1CollectedHeap::heap(); GCTraceTime(Info, gc) t(printGCMessage, g1h->gctimercm(), GCCause::nogc, true); IsGCActiveMark x; + SvcGCMarker sgcm(SvcGCMarker::OTHER); + TraceCollectorStats tcs(g1h->g1mm()->fullcollectioncounters()); cl->dovoid(); } ---------------------- Thanks, Yasumasa

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