RFR: 8057586: Explicit GC ignored if GCLocker is active [v3]

[Ivan Walulya]

On Thu, 30 Mar 2023 12:04:14 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Ivan Walulya has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   cleanup test
>
> src/hotspot/share/gc/g1/g1CollectedHeap.cpp line 2119:
> 
>> 2117:     if (counters_before.total_full_collections() != full_gc_count) {
>> 2118:       return true;
>> 2119:     }
> 
> The other two GCs does this check inside the locker-scope. I don't think there's any practical diff -- why the inconsistency?

Only difference is "time" at which changes were made (Initially on G1), then also I couldn't decide which version is cleaner.

> src/hotspot/share/gc/parallel/parallelScavengeHeap.cpp line 556:
> 
>> 554:     VMThread::execute(&op);
>> 555: 
>> 556:     if (!VM_ParallelGCSystemGC::is_cause_full(cause) || op.full_gc_succeeded()) {
> 
> Why `full_gc_succeeded` here? Doesn't the following `full_gc_count != total_full_collections` achieve the same purpose?

`full_gc_count != total_full_collections` is under locker-scope, so we can avoid that locking since we are sure at this point that gc_count was incremented.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13191#discussion_r1153258604
PR Review Comment: https://git.openjdk.org/jdk/pull/13191#discussion_r1153260399