RFR: 8321816: GenShen: Provide a minimum amount of time for an old collection to run [v3]

[Y. Srinivas Ramakrishna]

On Wed, 20 Dec 2023 23:27:29 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> Young collections are allowed to interrupt old collections. Under heavy load, this may result in starvation of old collections - which may in turn lead to even more memory pressure on the young generation. Adding a minimum guaranteed amount of time for the old gc to make progress will help avoid this situation.
>
> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Only start global cycles when metaspace is out of memory

src/hotspot/share/gc/shenandoah/shenandoahRegulatorThread.hpp line 80:

> 78:   bool start_global_cycle();
> 79: 
> 80:   bool should_unload_classes();

Could you also please write a 1-line documentation comment for this as well?

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/371#discussion_r1433326071