RFR: 8318706: Implementation of JDK-8276094: JEP 423: Region Pinning for G1 [v3]

[Thomas Schatzl]

On Mon, 30 Oct 2023 13:43:33 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Maybe rename `should_retain_evac_failed_region` to `should_keep_retained_region[_in_old]` or something?
>
> Is it possible to drop 1 so that an obj is evac-fail iff it's pinned or OOM? (I feel "retain" is on region-level.)

The `G1EvacFailureRegions` class is on region level. 

There is a need for a term that encompasses both pinned and evac-failed regions. So far we used "retained" (i.e. contents partially not moved), also in logging. I am obviously open for suggestions, but I am not sure "OOM" in any variant is a good name to replace current "evac-fail" regions. Right now I don't see a good name.

Maybe if we change `handle_evacuation_failure_par()` to something else? Like `handle_unmovable_object` or so to get rid of "evacuation failure" for objects? To some degree, we don't "fail" evacuation due to pinning, pinning is a conscious decision.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16342#discussion_r1376612711