RFR(XS): Heap memory usage counting not longer needs to be atomic

[Zhengyu Gu]

On 02/22/2017 02:53 PM, Aleksey Shipilev wrote:

> On 02/22/2017 08:45 PM, Zhengyu Gu wrote:
>> After guarding memory allocation with heap lock, memory usage counting also
>> under heap lock
>> or executed by VM thread during a safepoint.
>>
>> http://cr.openjdk.java.net/~zgu/shenandoah/memory_counting/webrev.00/
> Not sure.
>
> There is ShenandoahMonitoringSupport::update_counters() that polls these outside
> safepoint. Tried with -XX:+UsePerfData -XX:+ShenandoahRegionSampling? I am
> pretty sure that some JMX/JvmStat counters would eventually do this too.

Yes, I did. There is only a read, not updates.

-Zhengyu

>
> -Aleksey
>