8322732: ForkJoinPool may underutilize cores in async mode

[DougLea]

This set of changes address causes of poor utilization with small numbers of cores due to overly aggressive contention avoidance. A number of further adjustments were needed to still avoid most contention effects in deployments with large numbers of cores

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issues

• JDK-8322732: ForkJoinPool may underutilize cores in async mode (Bug - P4)
• JDK-8327854: Test java/util/stream/test/org/openjdk/tests/java/util/stream/WhileOpStatefulTest.java failed with RuntimeException (Bug - P4)

Reviewers

• Alan Bateman (@AlanBateman - Reviewer)

Reviewing

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[AlanBateman]

Viktor (mostly) and I have been testing and reviewing these changes at each iteration. I think we are happy with where things are at, significantly very positive in some of the streams/gatherer tests. The Starvation test is the canary to catch a scenario that has been observed along the way, but not with the current version. So I think this is good to integrate.

[viktorklang-ora]

Seconding @AlanBateman, I've reviewed and provided feedback on this PR multiple times, and have had numerous runs of parallel streams / gatherers and I think this is good to go. If I was a reviewer my vote would matter, but I'm adding this comment here as an "enthusiastic supporter". :)

[DougLea]

/issue JDK-8327854

[openjdk]

@DougLea
Adding additional issue to issue list: 8327854: Test java/util/stream/test/org/openjdk/tests/java/util/stream/WhileOpStatefulTest.java failed with RuntimeException.

[DougLea]

/integrate

[openjdk]

Going to push as commit 789f704.
Since your change was applied there have been 74 commits pushed to the master branch:

• 2c1b311: 8331854: ubsan: copy.hpp:218:10: runtime error: addition of unsigned offset to 0x7fc2b4024518 overflowed to 0x7fc2b4024510
• 765ad0e: 8331947: Preview creates checkbox for JEP-less preview feature
• 8e903ee: 8331896: JFR: Improve check for JDK classes
• 3cbdf8d: 8333554: Parallel: Remove unused PSParallelCompact::is_in
• 3944e67: 8312132: Add tracking of multiple address spaces in NMT
• d0052c0: 8333326: Linux Alpine build fails after 8302744
• 4369856: 8333130: MakeJAR2.sh uses hard-coded JDK version
• 1f09467: 8327368: javac crash when computing exhaustiveness checks
• 7dbd033: 8332499: Gtest codestrings.validate_vm fail on linux x64 when hsdis is present
• 9db7c95: 8332750: Broken link in CatalogFeatures.html
• ... and 64 more: https://git.openjdk.org/jdk/compare/7ab74c5f268dac82bbd36355acf8e4f3d357134c...master

Your commit was automatically rebased without conflicts.

[openjdk]

@DougLea Pushed as commit 789f704.

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