8335356: Shenandoah: Improve concurrent cleanup locking

[earthling-amzn]

Not clean, but conflicts were easy to resolve.

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Progress

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

Issue

• JDK-8335356: Shenandoah: Improve concurrent cleanup locking (Bug - P4)

Reviewers

• Y. Srinivas Ramakrishna (@ysramakrishna - Committer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/106/head:pull/106
$ git checkout pull/106

Update a local copy of the PR:
$ git checkout pull/106
$ git pull https://git.openjdk.org/shenandoah-jdk21u.git pull/106/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 106

View PR using the GUI difftool:
$ git pr show -t 106

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/shenandoah-jdk21u/pull/106.diff

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[openjdk]

@earthling-amzn 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:

8335356: Shenandoah: Improve concurrent cleanup locking

Reviewed-by: ysr

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[openjdk]

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

[mlbridge]

Webrevs

• 00: Full (070339c9)

[ysramakrishna]

This looks good. Would be good to backport this into JDK 21u-dev directly too.
(cc @pengxiaolong)

[earthling-amzn]

Yes, I'll open a PR to integrate to 21u-dev also.

/integrate

[openjdk]

Going to push as commit 2c22b6a.

[openjdk]

@earthling-amzn Pushed as commit 2c22b6a.

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