RFR: 8351077: Shenandoah: Update comments in ShenandoahConcurrentGC::op_reset_after_collect

[duke]

On Mon, 3 Mar 2025 20:12:34 GMT, Xiaolong Peng <xpeng at openjdk.org> wrote:

> This is a trivial PR to update the code comments in ShenandoahConcurrentGC::op_reset_after_collect.
> 
> After doing more test and analysis, we have a better understanding why reset bitmap of young gen after concurrent cycle may cause crash if there is pending old GC cycle to execute: When there is soft reference in old gen, but the referent is in young, reseting bitmap of young will cause wrong state of the soft reference, which may lead to expected cashes.

@pengxiaolong 
Your change (at version 3764bf7d41619a2b51bb860e7ae4005e7f8c0e37) is now ready to be sponsored by a Committer.

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PR Comment: https://git.openjdk.org/jdk/pull/23872#issuecomment-2695464781