RFR: 8336707: Contention of ForkJoinPool grows when stealing works [v29]

[Doug Lea]

> This addresses tendencies in previous update to increase fencing, scanning, and signalling that can increase contention, and slow down performance especially on ARM platforms. It also uses more ARM-friendly constructions to reduce overhead (leading to several changes that all of the same form),

Doug Lea has updated the pull request incrementally with one additional commit since the last revision:

  Ensure InnocuousForkJoinWorkerThread usable with or without SecurityManager

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21507/files
  - new: https://git.openjdk.org/jdk/pull/21507/files/a32e818d..0f5aa3dc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21507&range=28
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21507&range=27-28

  Stats: 66 lines in 2 files changed: 44 ins; 11 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/21507.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21507/head:pull/21507

PR: https://git.openjdk.org/jdk/pull/21507