RFR: 8338977: Parallel: Improve heap resizing heuristics [v3]

[Albert Mingkun Yang]

On Mon, 19 May 2025 11:05:40 GMT, Guoxiong Li <gli at openjdk.org> wrote:

>> Added checking for `from_space`.
>> 
>> If all live-objs don't fit in old-gen, leftovers will be kept in its own space.
>> 
>> 
>>   // Summarize the remaining spaces in the young gen.  The initial target space
>>   // is the old gen.  If a space does not fit entirely into the target, then the
>>   // remainder is compacted into the space itself and that space becomes the new
>>   // target.
>
>> If all live-objs don't fit in old-gen, leftovers will be kept in its own space.
> 
> Thanks for clarifying.

I removed this method, and added comments why it's undesirable to do young-gen resizing after a full-gc.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25000#discussion_r2168706034