On Wed, Aug 24, 2016 at 6:29 PM, Poonam Bajaj Parhar < poonam.ba...@oracle.com> wrote:
> Also, do you see entries like "*[G1Ergonomics (Mixed GCs) do not start > mixed GCs, reason:" *in the GC logs which mean that the mixed GCs are not > happening due to some reason. What is the reason listed with these log > entries? > Hi Poonam, Yes, I do see a few those, but only very early in the process lifetime, and nowhere near the Full GCs. 2016-08-24T10:33:04.733+0000: 8.460: [SoftReference, 0 refs, 0.0010108 secs]2016-08-24T10:33:04.734+0000: 8.461: [WeakReference, 383 refs, 0.0006608 secs]2016-08-24T10:33:04.735+0000: 8.462: [FinalReference, 4533 refs, 0.0020491 secs]2016-08-24T10:33:04.737+0000: 8.464: [PhantomReference, 0 refs, 15 refs, 0.0011945 secs]2016-08-24T10:33:04.738+0000: 8.465: [JNI Weak Reference, 0.0000360 secs] 8.467: [G1Ergonomics (Mixed GCs) do not start mixed GCs, reason: concurrent cycle is about to start] 2016-08-24T10:35:22.846+0000: 146.574: [SoftReference, 0 refs, 0.0011450 secs]2016-08-24T10:35:22.847+0000: 146.575: [WeakReference, 440 refs, 0.0006071 secs]2016-08-24T10:35:22.848+0000: 146.575: [FinalReference, 7100 refs, 0.0018074 secs]2016-08-24T10:35:22.850+0000: 146.577: [PhantomReference, 0 refs, 76 refs, 0.0013148 secs]2016-08-24T10:35:22.851+0000: 146.579: [JNI Weak Reference, 0.0000443 secs] 146.584: [G1Ergonomics (Mixed GCs) do not start mixed GCs, reason: concurrent cycle is about to start] 2016-08-24T10:35:56.507+0000: 180.234: [SoftReference, 0 refs, 0.0010184 secs]2016-08-24T10:35:56.508+0000: 180.235: [WeakReference, 138 refs, 0.0006883 secs]2016-08-24T10:35:56.508+0000: 180.236: [FinalReference, 3682 refs, 0.0023152 secs]2016-08-24T10:35:56.511+0000: 180.238: [PhantomReference, 0 refs, 45 refs, 0.0012558 secs]2016-08-24T10:35:56.512+0000: 180.239: [JNI Weak Reference, 0.0000197 secs] 180.247: [G1Ergonomics (Mixed GCs) do not start mixed GCs, reason: concurrent cycle is about to start] 2016-08-24T10:37:33.387+0000: 277.114: [SoftReference, 0 refs, 0.0010965 secs]2016-08-24T10:37:33.388+0000: 277.115: [WeakReference, 5 refs, 0.0006378 secs]2016-08-24T10:37:33.388+0000: 277.116: [FinalReference, 3440 refs, 0.0028640 secs]2016-08-24T10:37:33.391+0000: 277.119: [PhantomReference, 0 refs, 0 refs, 0.0011392 secs]2016-08-24T10:37:33.392+0000: 277.120: [JNI Weak Reference, 0.0000148 secs] 277.130: [G1Ergonomics (Mixed GCs) do not start mixed GCs, reason: candidate old regions not available] Does that tell you anything? > > Thanks, > Poonam > > On 8/24/2016 3:18 PM, Jenny Zhang wrote: > > More comments about the questions > > Thanks > Jenny > > On 8/24/2016 11:43 AM, Vitaly Davidovich wrote: > > Right before the Full GC, ergonomics report a failure to expand the heap > due to an allocation request of 32 bytes. Is this implying that a mutator > tried to allocate 32 bytes but couldn't? How do I reconcile that with > Eden+Survivor occupancy reported right above that? > > Yes, it means the mutator tries to allocate 32byte but can not get it. > Heap won't expand as it already reaches max heap. > > Do you see any humongous objects allocatoin? > > > Young gen is sized to 30GB, total heap is 96GB. Allocation rate of the > application is roughly 1GB/s. Am I correct in assuming that allocation is > outpacing concurrent marking, based on the above? What tunable(s) would you > advise to tweak to get G1 to keep up with the allocation rate? I'm ok > taking some throughput hit to mitigate 90s+ pauses. > > The entire log might give a better picture. Especially if the marking > cycle is triggered, how well the mixed gc cleans up the heap. > > _______________________________________________ > hotspot-gc-use mailing list > hotspot-gc-use@openjdk.java.net > http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use > > > > _______________________________________________ > hotspot-gc-use mailing list > hotspot-gc-use@openjdk.java.net > http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use > >
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