RFR: 8315149: Add hsperf counters for CPU time of internal GC threads [v53]

[Volker Simonis]

On Thu, 30 Nov 2023 09:46:03 GMT, Stefan Johansson <sjohanss at openjdk.org> wrote:

>> Jonathan Joo has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add missing include
>
> src/hotspot/share/gc/parallel/parallelScavengeHeap.cpp line 905:
> 
>> 903:   gc_threads_do(&tttc);
>> 904: 
>> 905:   CPUTimeCounters::publish_gc_total_cpu_time();
> 
> As I suggested in the other comment, maybe we should not keep the total counter, but if we do we need to make sure the destructor of the closure is run before the call to `publish_gc_total_cpu_time()`. Otherwise we will publish a not yet updated value.

I still think that a total counter is useful and I'd appreciate if you can keep it. To second what @caoman said before, it is GC agnostic, easy to use even for non GC experts and future proof with regards to implementation changes in the GCs. Please keep it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15082#discussion_r1412322098