RFR: 8369611: Remove safepoint synchronization from ParallelScavengeHeap and SerialHeap

Fri Oct 10 23:15:15 UTC 2025

In the discussion of [JDK-8369392](https://bugs.openjdk.org/browse/JDK-8369392), @kimbarrett pointed out that StringDedup thread is now derived from JavaThread, but ParallelScavengeHeap and SerialHeap still have conditional STS synchronization at safepoint, which is not needed, as a result of removing the conditional STS synchronization, we could remove the remove safepoint synchronization from ParallelScavengeHeap and SerialHeap.

Test:
  - [x] tier1

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Commit messages:
 - 8369611: Remove safepoint synchronization from ParallelScavengeHeap and SerialHeap

Changes: https://git.openjdk.org/jdk/pull/27755/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27755&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8369611
  Stats: 29 lines in 4 files changed: 0 ins; 29 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27755.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27755/head:pull/27755

PR: https://git.openjdk.org/jdk/pull/27755