RFR: 8246585: ForkJoin updates [v3]

[Martin Buchholz]

> 8246585: ForkJoin updates

Martin Buchholz has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:

  JDK-8246585

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Changes: https://git.openjdk.java.net/jdk/pull/1646/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1646&range=02
  Stats: 3291 lines in 7 files changed: 1312 ins; 890 del; 1089 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1646.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1646/head:pull/1646

PR: https://git.openjdk.java.net/jdk/pull/1646