RFR: 8325574: Shenandoah: Simplify and enhance reporting of requested GCs [v3]

[Aleksey Shipilev]

On Mon, 12 Feb 2024 21:41:36 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> src/hotspot/share/gc/shenandoah/shenandoahCollectorPolicy.cpp line 138:
>> 
>>> 136:   out->cr();
>>> 137:   out->print_cr(SIZE_FORMAT_W(5) " Successful Concurrent GCs (%.2f%%)", _success_concurrent_gcs, percent_of(_success_concurrent_gcs, completed_gcs));
>>> 138:   if (ExplicitGCInvokesConcurrent) {
>> 
>> Instead of relying on flags here, should we explicitly (pun intended) record `_explicit_collection_causes` and `_implicit_collection_causes`?
>
> That is what used to happen in `ShenandoahControlThread`. It feels like duplicating a result that can be derived from recording the gc causes. The `ExplicitGCInvokesConcurrent` and `ShenandoahImplicitGCInvokesConcurrent` flags aren't manageable, so I don't expect them to be different when the report is generated. I suppose that could change in the future... I'd be more inclined to not tally them at all and just leave the report to show the individual causes without classifying them.

All right, fine, if this would be a problem later, we would reconsider.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17795#discussion_r1489620291