Degenerated GC

[Zhengyu Gu]

shenandoahHeap.cpp:

1600
1601     // Allocations happen during concurrent preclean, record peak 
after the phase:
1602     shenandoahPolicy()->record_peak_occupancy();
1603   }
1604
1605   // Allocations happen during bitmap cleanup, record peak after 
the phase:
1606   shenandoahPolicy()->record_peak_occupancy();

May call twice.


Otherwise, looks good.

-Zhengyu



On 01/19/2018 02:55 AM, Aleksey Shipilev wrote:
> On 01/18/2018 08:51 PM, Aleksey Shipilev wrote:
>> On 01/18/2018 04:18 PM, Aleksey Shipilev wrote:
>>> http://cr.openjdk.java.net/~shade/shenandoah/degenerated-gc/webrev.01/
>>
>> Amped up alloc-failure injection, and that exposed a few bugs. Fixed them:
>>    http://cr.openjdk.java.net/~shade/shenandoah/degenerated-gc/webrev.02/
>>
>> GCBasher runs for half an hour now without problems. Running further...
> 
> 8-hour GCBasher passes with:
> 
> $ -Xmx1g -XX:+UseShenandoahGC -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
> -XX:ShenandoahGCHeuristics=aggressive -XX:+ShenandoahDegenerateALot TestGCBasherWithShenandoah 28800000
> 
> [27665.812s][info][gc,stats       ] 85556 successful concurrent GCs
> [27665.812s][info][gc,stats       ]      0 invoked explicitly
> [27665.812s][info][gc,stats       ]
> [27665.812s][info][gc,stats       ] 44995 Degenerated GCs
> [27665.812s][info][gc,stats       ]   44995 caused by allocation failure
> [27665.812s][info][gc,stats       ]   8628 upgraded to Full GC
> [27665.812s][info][gc,stats       ]
> [27665.812s][info][gc,stats       ] 8758 Full GCs
> [27665.812s][info][gc,stats       ]      0 invoked explicitly
> [27665.812s][info][gc,stats       ]    130 caused by allocation failure
> [27665.812s][info][gc,stats       ]   8628 upgraded from Degenerated GC
> 
> So, I am pretty sure it works :)
> 
> -Aleksey
>