RFR: 8365557: Parallel: Refactor ParallelScavengeHeap::mem_allocate_work

Thu Aug 14 14:55:51 UTC 2025

Extract out multi-thread-safe old-gen allocation API call outside the critical-region to streamline the flow in `mem_allocate_work`.

Test: tier1-3

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Commit messages:
 - pgc-mem-allocate-refactor

Changes: https://git.openjdk.org/jdk/pull/26779/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26779&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365557
  Stats: 47 lines in 2 files changed: 14 ins; 27 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/26779.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26779/head:pull/26779

PR: https://git.openjdk.org/jdk/pull/26779