Odd G1GC behavior on 8u91

[Poonam Bajaj Parhar]

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?

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.
>
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