RFR(XS): make shared variables volatile

[Aleksey Shipilev]

On 09/21/2016 03:24 PM, Zhengyu Gu wrote:
> This is a simple webrev that makes a few shared variables volatile:
> 
> http://cr.openjdk.java.net/~zgu/volatile/webrev/

Wait, why do we have to mark the methods "volatile"? Are we suggesting
the ShenandoahHeap (receiver) instance should be volatile too?

Thanks,
-Aleksey