8345423: Shenandoah: Parallelize concurrent cleanup

[pengxiaolong]

Clean backport, improve performance of concurrent cleanup of Shenandoah and GenShen, remove the use of heap lock from concurrent cleanup.

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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-8345423: Shenandoah: Parallelize concurrent cleanup (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/22991/head:pull/22991
$ git checkout pull/22991

Update a local copy of the PR:
$ git checkout pull/22991
$ git pull https://git.openjdk.org/jdk.git pull/22991/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 22991

View PR using the GUI difftool:
$ git pr show -t 22991

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Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/22991.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back xpeng! A progress list of the required criteria for merging this PR into jdk24 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 change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

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

[openjdk]

@pengxiaolong 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 (720e8c92)