8309956: Shenandoah: Strengthen the mark word check in string dedup

[shipilev]

Clean backport to improve Shenandoah reliability.

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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

Issue

• JDK-8309956: Shenandoah: Strengthen the mark word check in string dedup (Enhancement - P4)

Reviewers

• Roman Kennke (@rkennke - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21.git pull/19/head:pull/19
$ git checkout pull/19

Update a local copy of the PR:
$ git checkout pull/19
$ git pull https://git.openjdk.org/jdk21.git pull/19/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 19

View PR using the GUI difftool:
$ git pr show -t 19

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21/pull/19.diff

Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back shade! 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]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

@shipilev 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

• 00: Full (eaeefacf)

[rkennke]

Looks good, thanks!

[openjdk]

@shipilev 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:

8309956: Shenandoah: Strengthen the mark word check in string dedup

Reviewed-by: rkennke

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 no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential 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.

[shipilev]

/integrate

[openjdk]

Going to push as commit 0ac9275.

[openjdk]

@shipilev Pushed as commit 0ac9275.

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