RFR: 8355336: GenShen: Resume Old GC even with back-to-back Young GC triggers

[William Kemper]

On Wed, 23 Apr 2025 00:57:53 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

> Allow old-gen concurrent marking cycles to get their full time slice even when young-gc is triggered back-to-back.

I'm okay with this, but it will have the regulator thread give higher priority to the old generation when the collector is idle. Have we looked closely at performance results?

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

> 78:           _old_heuristics->cancel_trigger_request();
> 79:         } else if (start_young_cycle()) {
> 80:             log_debug(gc)("Heuristics request for young collection accepted");

Indentation looks a little off here.

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Changes requested by wkemper (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24810#pullrequestreview-2788071594
PR Review Comment: https://git.openjdk.org/jdk/pull/24810#discussion_r2056487435