[jdk21u] RFR: 8315692: Parallelize gc/stress/TestStressRSetCoarsening.java test

Wed Nov 22 13:43:24 UTC 2023

The commit includes backporting a564d436c722f14041231158f21c4ad3a2f6a3a5 from upstream tp jdk21u. The hunks were applied cleanly. Below are the results upon running in AL2_x86_64:
* after_release: 1573.15s user 63.94s system 270% cpu 10:05.94 total
* after_fastdebug: 8382.45s user 747.00s system 493% cpu 30:51.02 total
* before_release: 1514.58s user 69.27s system 109% cpu 24:10.98 total
* before_fastdebug: 2934.79s user 66.46s system 112% cpu 44:16.28 total

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Commit messages:
 - Backport a564d436c722f14041231158f21c4ad3a2f6a3a5

Changes: https://git.openjdk.org/jdk21u/pull/397/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=397&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315692
  Stats: 63 lines in 1 file changed: 55 ins; 1 del; 7 mod
  Patch: https://git.openjdk.org/jdk21u/pull/397.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/397/head:pull/397

PR: https://git.openjdk.org/jdk21u/pull/397