RFR: Concurrent partial should check for cancellation

[Roman Kennke]

Am 09.10.2017 um 23:19 schrieb Aleksey Shipilev:
> http://cr.openjdk.java.net/~shade/shenandoah/concpartial-cancellation/webrev.01/
>
> There are test deadlocks with LRU partial heuristics on my machine. The symptom is similar to SLT
> deadlock we have seen in 8u, but this time it is slightly different. Java thread is stuck in
> oom_during_evacuation during the partial cycle. VMThread is stuck waiting for the safepoint, and for
> that thread. This seems to happen because OOM is happening during concurrent partial, and we are
> stuck while trying to go to final partial pause.
>
> Concurrent cycle avoids that by checking for cancellation, and ShenandoahConcurrentThread handles
> putting the evac_in_progress flag down on cancellation path. We should do the same for concurrent
> partial now, for both correctness and symmetry reasons.
>
> Testing: hotspot_gc_shenandoah (+ failed tests)
>
> Thanks,
> -Aleksey
>
Looks good