8325754: Dead AbstractQueuedSynchronizer$ConditionNodes survive minor garbage collections

[viktorklang-ora]

More aggressively breaking chains in order to prevent nodes promoted to older generations standing in the way for collecting younger nodes. I decided that it was most efficient to add this logic to the else-branch of updating the firstWaiter and lastWaiter.

There's a race with unlinkCancelledWaiters() but according to @DougLea it should be a benign one.

There's a performance impact of this, but as it is a plain write, and one to null at that, it should be acceptable.

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Issue

• JDK-8325754: Dead AbstractQueuedSynchronizer$ConditionNodes survive minor garbage collections (Bug - P4)

Reviewers

• Alan Bateman (@AlanBateman - Reviewer)

Reviewing

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• 00: Full (fbc45be1)

[AlanBateman]

If the race with unlinking non-waiting nodes is benign then this should be okay.

[openjdk]

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8325754: Dead AbstractQueuedSynchronizer$ConditionNodes survive minor garbage collections

Reviewed-by: alanb

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At the time when this comment was updated there had been 43 new commits pushed to the master branch:

• 4406915: 8323274: C2: array load may float above range check
• cc1e216: 8326461: tools/jlink/CheckExecutable.java fails as .debuginfo files are not executable
• 10eafdc: 8325870: Zap end padding bits for ArrayOops in non-release builds
• 0f4cd8f: 8326414: Serial: Inline SerialHeap::create_rem_set
• 8b30503: 8323695: RenderPerf (2D) enhancements (23.12)
• 8e5f6dd: 8324243: Compilation failures in java.desktop module with gcc 14
• 0bcece9: 8325342: Remove unneeded exceptions in compare.sh
• 64f7972: 8326158: Javadoc for java.time.DayOfWeek#minus(long)
• f0f4d63: 8326351: Update the Zlib version in open/src/java.base/share/legal/zlib.md to 1.3.1
• 51e2dde: 8326235: RISC-V: Size CodeCache for short calls encoding
• ... and 33 more: https://git.openjdk.org/jdk/compare/5c5a282f91dd28b306673ca2bcc30dec451e7a7d...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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[DougLea]

Thanks for doing this. Looks good.

[viktorklang-ora]

/integrate

[openjdk]

Going to push as commit 60cbf29.
Since your change was applied there have been 93 commits pushed to the master branch:

• da14aa4: 8017234: Hotspot should stop using mapfiles
• d482c1a: 8326524: Rename agent_common.h
• e85355a: 8320005: Allow loading of shared objects with .a extension on AIX
• 5d3d40d: 8326659: Serial: Remove redundant TenuredSpace::print_on
• 7583419: 8324828: Avoid multiple search of reserved regions during splitting
• c5f1dcc: 8325082: Rename headers named 'heapRegion*' of G1
• 4d82ea1: 8325144: C1: Optimize CriticalEdgeFinder
• a48f596: 8322179: RISC-V: Implement SHA-1 intrinsic
• 5daf63b: 8326636: Problem list StartupOutput.java due to 8326615
• 97aca09: 8326717: Disable stringop-overflow in shenandoahLock.cpp
• ... and 83 more: https://git.openjdk.org/jdk/compare/5c5a282f91dd28b306673ca2bcc30dec451e7a7d...master

Your commit was automatically rebased without conflicts.

[openjdk]

@viktorklang-ora Pushed as commit 60cbf29.

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