RFR: 8311602 GenShen: Decouple generational mode heuristics [v3]

[William Kemper]

On Wed, 12 Jul 2023 20:59:01 GMT, Y. Srinivas Ramakrishna <ysr at openjdk.org> wrote:

>> William Kemper has updated the pull request incrementally with three additional commits since the last revision:
>> 
>>  - Use interface in heuristic initialization methods
>>  - Call base class method with more intuitive syntax.
>>  - Remove unused fields and methods
>
> src/hotspot/share/gc/shenandoah/heuristics/shenandoahHeapCharacteristics.hpp line 30:
> 
>> 28: #include "utilities/globalDefinitions.hpp"
>> 29: 
>> 30: class ShenandoahHeapCharacteristics {
> 
> Please include a brief documentation comment of what it represents and what its intended use is.

I'll do this on the `openjdk/jdk` PR:  https://github.com/openjdk/jdk/pull/14856

> src/hotspot/share/gc/shenandoah/shenandoahGeneration.cpp line 953:
> 
>> 951: void ShenandoahGeneration::record_success_concurrent(bool abbreviated) {
>> 952:   ShenandoahHeap* heap = ShenandoahHeap::heap();
>> 953:   abbreviated = abbreviated && heap->mode()->is_generational();
> 
> You'll need to explain this change. Why should it matter here if we are generational or not for an abbreviated collection to be counted as one. This is confusing to the lay reader like me :-)

I've reverted this. The idea here was to restrict the scope of this change to only the generational mode, but it doesn't really solve the underlying problems.

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/292#discussion_r1268504100
PR Review Comment: https://git.openjdk.org/shenandoah/pull/292#discussion_r1268464031