RFR: 8336707: Contention of ForkJoinPool grows when stealing works [v20]

[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 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 38 additional commits since the last revision:

 - Merge branch 'openjdk:master' into JDK-8336707
 - Add CLEANED runState
 - Merge branch 'openjdk:master' into JDK-8336707
 - More shutdown streamlining
 - Don't report termination while cancellations in progress
 - Reduce read contention
 - Merge branch 'openjdk:master' into JDK-8336707
 - Reduce shutdown overhead and contention
 - dropWaiters now back to releaseAll
 - Merge branch 'openjdk:master' into JDK-8336707
 - ... and 28 more: https://git.openjdk.org/jdk/compare/302782db...96183529

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21507/files
  - new: https://git.openjdk.org/jdk/pull/21507/files/3a88605f..96183529

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21507&range=19
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21507&range=18-19

  Stats: 8940 lines in 387 files changed: 6024 ins; 1491 del; 1425 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