RFR: 8357445: G1: Time-Based Heap Uncommit During Idle Periods [v2]

[Thomas Schatzl]

On Thu, 17 Jul 2025 01:41:35 GMT, Monica Beckwith <mbeckwit at openjdk.org> wrote:

>> My argument is related to consistency, if there are reasons to have this logging distinct from the `(gc, ergo, heap)`, that is fine by me.
>
> Thank you for being open to the distinct logging tags. I'll keep (gc,sizing) to maintain the semantic clarity for time-based heap sizing troubleshooting. This will help users and support teams isolate time-based sizing behavior from traditional ergonomic heap management.

Probably I would prefer `gc, ergo, sizing` - heap sizing is part of ergonomics and doing so allows you to specifically enable it and the same time (with `gc+ergo*`) catch it with other ergonomic decisions.

Potentially more log messages should be moved to that logging too. Maybe make a CR that says something like "G1: Consider putting heap sizing decisions under gc+ergo+sizing`.

Note that I think we somewhat already use `gc+ergo+heap` for that, so the new flag might be redundant.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26240#discussion_r2212456529