RFR(S) 8225813: Shenandoah: Obsolete ShenandoahSuspendibleWorkers flag, as suspendible workers are required

[Zhengyu Gu]

On 6/15/19 3:35 PM, Roman Kennke wrote:
> Can you give a little bit of explanation why workers need to be
> suspended at safepoints for concurrent root processing?

Concurrent processing uses workers and safepoint parallel task also 
utilizes workers, and shenandoah shares workers, so they can not overlap.


-Zhengyu

> 
> Other than that, the patch looks good.
> 
> Roman
> 
>> Please review this patch that makes suspendible workers required,
>> instead of optional, and obsoletes the corresponding flag.
>>
>> Suspendible workers are required for concurrent root processing.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8225813
>> Webrev: http://cr.openjdk.java.net/~zgu/JDK-8225813/webrev.00/index.html
>>
>> Test:
>>    hotspot_gc_shenandoah (fastdebug and release)
>>
>> Thanks,
>>
>> -Zhengyu
>