RFR: 8348594: Shenandoah: Do not penalize for degeneration when not the fault of triggering heuristic [v2]

[Kelvin Nilsen]

On Tue, 4 Feb 2025 16:14:49 GMT, Paul Hohensee <phh at openjdk.org> wrote:

>> Kelvin Nilsen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Respond to reviewer feedback
>
> src/hotspot/share/gc/shenandoah/heuristics/shenandoahAdaptiveHeuristics.cpp line 318:
> 
>> 316: 
>> 317:   if (ShenandoahHeuristics::should_start_gc()) {
>> 318:     _start_gc_is_pending = true;
> 
> I assume there's no race here, i.e., only one thread reads/writes _start_gc_is_pending. If there's a race, make sure it's benign. In either case, _start_gc_is_pending is made "sticky" by this code.

There is no race.  A single control thread queries should_start-gc() and that is the same thread that initiates the GC.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23305#discussion_r1949828557