RFR (S): 8165858: heapRegionManager is missing volatile qualifier for _claims

[Kim Barrett]

> On Sep 19, 2016, at 7:47 AM, Erik Österlund <erik.osterlund at oracle.com> wrote:
> 
> Hi,
> 
> This bug is a split out of the larger JDK-8033552 for adding volatile qualifiers to lock-free code.
> The motivation is to make our implementation more robust since these kind of issues have struck us a few times too many already.
> 
> CR: https://bugs.openjdk.java.net/browse/JDK-8165858
> Webrev: http://cr.openjdk.java.net/~eosterlund/8165858/webrev.00/
> 
> This specific CR handles the lack of volatile qualifiers for the _claims field of the HeapRegionClaimer class in the heapRegionManager files. It is part of a lock-free protocol for claiming reagions, and should use a volatile qualifier to be more robust.
> 
> Testing: JPRT
> 
> I will need a sponsor to push this.
> 
> Thanks,
> /Erik

Looks good.