RFR: 8235355: Shenandoah: Resolve deadlock between OOM handler and nmethod lock

[Zhengyu Gu]

Look good.

Thanks,

-Zhengyu

On 12/4/19 3:02 PM, Roman Kennke wrote:
> JDK-8235337 changed OOM scoping, but unfortunately it causes a deadlock.
> See bug report for more details:
> 
> https://bugs.openjdk.java.net/browse/JDK-8235355
> 
> The proposed fix ensures that we're entering the nmethod lock and OOM
> scope in the right and the same order always. It reverts JDK-8235337 and
> puts an extra OOM scope on the path that caused the original bug.
> 
> http://cr.openjdk.java.net/~rkennke/JDK-8235355/webrev.00/
> 
> Testing: hotspot_gc_shenandoah, specjvm with +aggressive and
> +ShenandoahOOMDuringEvacALot
> 
> Can I please get a review?
> 
> Thanks,
> Roman
>