RFR: 8219613: Use NonJavaThread PtrQueues

[Thomas Schatzl]

Hi,

On Mon, 2019-02-25 at 22:27 -0500, Kim Barrett wrote:
> Please review this change to G1 and Shenandoah to use the already
> extent thread-local PtrQueues in NonJavaThreads, rather than using
> shared queues that require locking.
> 
> 
[...]
> https://bugs.openjdk.java.net/browse/JDK-8219613
> 
> Webrev:
> http://cr.openjdk.java.net/~kbarrett/8219613/open.01/
> 
> gc/shared/barrierSet.cpp is in the webrev, but ended up not being
> changed.

looks good.

Thomas