RFR: 8369097: Parallel: Support allocation in from space when heap is too full [v2]

[Francesco Andreuzzi]

On Tue, 7 Oct 2025 18:25:47 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Support allocation in from-space of young-gen in extreme cases (heap is almost full), so that gc-log shows used-heap is almost at max-heap when OOM is thrown.
>> 
>> Test: tier1-5
>
> Albert Mingkun Yang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'master' into pgc-allocate-in-from-space
>  - pgc-allocate-in-from-space

Marked as reviewed by fandreuzzi (Author).

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PR Review: https://git.openjdk.org/jdk/pull/27620#pullrequestreview-3323226509