RFR: 8277736: G1: Allow forced evacuation failure of first N regions in collection set [v2]

[Thomas Schatzl]

On Wed, 1 Dec 2021 09:27:15 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> I will refine the explanation specifically.
>> As Thomas suggested, an random selection will be added later, I plan to add another bool option to indicate if it's random selection or not, so will keep `G1EvacuationFailureALotCSetPercent`.
>
> Another, imo better way would be allowing a string for the type of selection algorithm, like `VerifyGCType`, with current possible values being `NthObject` (or just default) and `FirstRegions` or so.

That could be extended to `RandomRegions` later.

This needs another flag though, maybe something like `G1EvacuationFailureALotObjectSelectionType` (random name right now, probably you will come up with something better).

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PR: https://git.openjdk.java.net/jdk/pull/6561