8351000: StringBuilder getChar and putChar robustness

[RogerRiggs]

Improve StringBuilder getChar and putChar robustness with racy updates to StringBuilder.
Test racing threads with append, insert, and reading characters.

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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-8351000: StringBuilder getChar and putChar robustness (Bug - P4)

Reviewers

• Chen Liang (@liach - Reviewer)
• Raffaello Giulietti (@rgiulietti - Reviewer) Review applies to 0feabe83
• Per Minborg (@minborg - Reviewer) Review applies to 0feabe83
• Lance Andersen (@LanceAndersen - Reviewer)

Reviewing

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$ git checkout pull/24951

Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/24951/head

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Using Webrev

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[bridgekeeper]

👋 Welcome back rriggs! 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]

@RogerRiggs 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:

8351000: StringBuilder getChar and putChar robustness

Reviewed-by: liach, lancea, rgiulietti, pminborg

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 38 new commits pushed to the master branch:

• 482538b: 8351884: Refactor bug8033699.java test code
• 0110aca: 8354791: Use Hashtable.putIfAbsent in CSS constructor
• 526951d: 8354145: G1: UseCompressedOops boundary is calculated on maximum heap region size instead of maxiumum ergonomic heap region size
• ... and 35 more: https://git.openjdk.org/jdk/compare/2f8448034f28276ad5ac1edfa0fb8650e47d4ffa...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.

[openjdk]

@RogerRiggs The following label will be automatically applied to this pull request:

• core-libs

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

[mlbridge]

Webrevs

• 01: Full - Incremental (e2b842cb)
• 00: Full (0feabe83)

[liach]

Thanks, other changes look good to me!

[rgiulietti]

Looks fine.
Thanks @RogerRiggs

[minborg]

LGTM. Thanks for these improvements.

[turbanoff]

Let's cleanup test a bit

[liach]

Good cleanup, thanks @turbanoff!

[wenshao]

It may be easier to understand if initString is renamed to repeat

[LanceAndersen]

Test cleanup looks fine Roger

[RogerRiggs]

/integrate

[openjdk]

Going to push as commit 4c695fa.
Since your change was applied there have been 38 commits pushed to the master branch:

• 482538b: 8351884: Refactor bug8033699.java test code
• 0110aca: 8354791: Use Hashtable.putIfAbsent in CSS constructor
• 526951d: 8354145: G1: UseCompressedOops boundary is calculated on maximum heap region size instead of maxiumum ergonomic heap region size
• ... and 35 more: https://git.openjdk.org/jdk/compare/2f8448034f28276ad5ac1edfa0fb8650e47d4ffa...master

Your commit was automatically rebased without conflicts.

[openjdk]

@RogerRiggs Pushed as commit 4c695fa.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.