JDK-8298138: Shenandoah: HdrSeq asserts "sub-bucket index (512) overflow for value ( 1.00)"

[ysramakrishna]

JBS link: https://bugs.openjdk.org/browse/JDK-8298138

• Fixed a boundary condition that was triggering an assert.
• Added a simple-minded gtest for HdrSeq, which allows one to exercise the asserting code in a debug build.
• Tested with: CONF=slowdebug make run-test TEST="gtest:BasicShenandoahNumberSeqTest"

---

Progress

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Issue

• JDK-8298138: Shenandoah: HdrSeq asserts "sub-bucket index (512) overflow for value ( 1.00)"

Reviewers

• Roman Kennke (@rkennke - Reviewer)
• Aleksey Shipilev (@shipilev - Reviewer)

Reviewing

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[bridgekeeper]

👋 Welcome back ysr! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@ysramakrishna The following labels will be automatically applied to this pull request:

• hotspot-gc
• shenandoah

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 02: Full - Incremental (a0edcbda)
• 01: Full - Incremental (a714630c)
• 00: Full (fb5cd5d0)

[rkennke]

Hi Ramki,
The change looks good. I have a few minor comments.

[ysramakrishna]

@rkennke & @shipilev : could you folks please review and approve? I made the changes requested by Roman.

Thanks!
-- Ramki

[shipilev]

So the failure is: we want the bucket to cover [a; a+n), but current code makes it cover [a; a+n], which means the right-most value would overflow its assignment for sub-bucket? If so, the fix looks good.

[openjdk]

@ysramakrishna This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8298138: Shenandoah: HdrSeq asserts "sub-bucket index (512) overflow for value ( 1.00)"

Reviewed-by: rkennke, shade

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 12 new commits pushed to the master branch:

• ea108f5: 8298129: Let checkpoint event sizes grow beyond u4 limit
• 165dcdd: 8297718: Make NMT free:ing protocol more granular
• fbe7b00: 8298173: GarbageCollectionNotificationContentTest test failed: no decrease in Eden usage
• d8ef60b: 8298272: Clean up ProblemList
• 9353899: 8298175: JFR: Common timestamp for periodic events
• 94575d1: 8295116: C2: assert(dead->outcnt() == 0 && !dead->is_top()) failed: node must be dead
• 49b8622: 8290850: C2: create_new_if_for_predicate() does not clone pinned phi input nodes resulting in a broken graph
• 2f426cd: 8298375: Bad copyright header in test/jdk/java/lang/Character/Supplementary.java
• b9346e1: 8298033: Character.codePoint{At|Before}(char[], int, int) doesn't do JavaDoc-specified check
• 297bf6a: 8287397: Print top-level exception when snippet fails to read file
• ... and 2 more: https://git.openjdk.org/jdk/compare/1166c8e2c0047869cd50b7ddc5355290ac2a695a...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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[rkennke]

Looks good, thank you!

[ysramakrishna]

Thanks for the reviews, Roman and Alexey!

[ysramakrishna]

/integrate

[openjdk]

Going to push as commit c16eb89.
Since your change was applied there have been 19 commits pushed to the master branch:

• 3dfadee: 8292289: [vectorapi] Improve the implementation of VectorTestNode
• d35e840: 8297295: Remove ThreadGroup.allowThreadSuspension
• 175e3d3: 8296149: Start of release updates for JDK 21
• d562d3f: 8297642: PhaseIdealLoop::only_has_infinite_loops must detect all loops that never lead to termination
• fc52f21: 8298255: JFR provide information about dynamization of number of compiler threads
• e555d54: 8298383: JFR: GenerateJfrFiles.java lacks copyright header
• c084431: 8298379: JFR: Some UNTIMED events only sets endTime
• ea108f5: 8298129: Let checkpoint event sizes grow beyond u4 limit
• 165dcdd: 8297718: Make NMT free:ing protocol more granular
• fbe7b00: 8298173: GarbageCollectionNotificationContentTest test failed: no decrease in Eden usage
• ... and 9 more: https://git.openjdk.org/jdk/compare/1166c8e2c0047869cd50b7ddc5355290ac2a695a...master

Your commit was automatically rebased without conflicts.

[openjdk]

@ysramakrishna Pushed as commit c16eb89.

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