RFR: Add task termination and enhanced task queue state tracking

[Zhengyu Gu]

Updated:
 
http://cr.openjdk.java.net/~zgu/shenandoah/termination_tracking/webrev.01/


-XX:+ShenandoahTerminationTrace

[info][gc,stats]   Finish Queues             =     0.01 s (a =      181 
us) (n =    36)
[info][gc,stats]     Termination             =     0.00 s (a =       43 
us) (n =    36)

[info][gc,stats] Concurrent Marking          =     3.79 s (a =   105316 
us) (n =    36)
[info][gc,stats]   Termination               =     0.11 s (a =     2940 
us) (n =    36)

-XX:-ShenandoahTerminationTrace
[info][gc,stats]   Finish Queues             =     0.01 s (a =      154 
us) (n =    37)
[info][gc,stats] Concurrent Marking          =     3.99 s (a =   107877 
us) (n =    37)

Thanks,

-Zhengyu

On 07/12/2018 10:05 AM, Aleksey Shipilev wrote:
> On 07/12/2018 03:39 PM, Zhengyu Gu wrote:
>> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/termination_tracking/webrev.00/
> 
> The patch looks good.
> 
> How often do threads request termination? Are we sure this tracking does not introduce its own
> latencies, e.g. due timer calls and contention on counters themselves? Maybe we can guard it with
> the diagnostic ShenandoahTerminationTrace flag in ShenandoahTerminationTimings to be able to dissect?
> 
> Thanks,
> -Aleksey
> 
>