8297295: Remove ThreadGroup.allowThreadSuspension

[AlanBateman]

Another small step in the multi-release/multi-year effort to remove cruft from Thread/ThreadGroup.

java.lang.ThreadGroup.allowThreadSuspension(boolean) dates from JDK 1.1 and the Classic VM. The method controlled whether threads were suspended when the GC failed. It appears to have interacted with a callback mechanism that could potentially free memory, allowing the GC to retry. The method was never specified .

The method was deprecated and changed to do nothing in JDK 1.2. It was deprecated for removal in Java 14.

A corpus analysis of 30M classes in 130k artifacts found 0 usages of this method.

It is time to finally remove this method. The compatibility impact should be negligible. Joe, Stuart and I discussed briefly and think early in JDK 21 is a good time to do this.

---

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
• Change requires a CSR request to be approved

Issues

• JDK-8297295: Remove ThreadGroup.allowThreadSuspension
• JDK-8297331: Remove ThreadGroup.allowThreadSuspension (CSR)

Reviewers

• Jaikiran Pai (@jaikiran - Reviewer) ⚠️ Review applies to 427025eb
• Stuart Marks (@stuart-marks - Reviewer) ⚠️ Review applies to 427025eb
• Chris Hegarty (@ChrisHegarty - Reviewer) ⚠️ Review applies to 427025eb
• Joe Darcy (@jddarcy - Reviewer) ⚠️ Review applies to 427025eb

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk pull/11373/head:pull/11373
$ git checkout pull/11373

Update a local copy of the PR:
$ git checkout pull/11373
$ git pull https://git.openjdk.org/jdk pull/11373/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 11373

View PR using the GUI difftool:
$ git pr show -t 11373

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/11373.diff

[bridgekeeper]

👋 Welcome back alanb! 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]

@AlanBateman 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.

[AlanBateman]

/csr

[openjdk]

@AlanBateman has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@AlanBateman please create a CSR request for issue JDK-8297295 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

[mlbridge]

Webrevs

• 02: Full - Incremental (3b06acd6)
• 01: Full - Incremental (639b6b58)
• 00: Full (427025eb)

[jaikiran]

Joe, Stuart and I discussed briefly and think early in JDK 21 is a good time to do this.

I guess, this would then mean this PR will be integrated into mainline after 8th December when the branch for JDK 20 will be forked https://openjdk.org/projects/jdk/20/#Schedule?

[jaikiran]

Looks fine to me.

[stuart-marks]

@jaikiran wrote:

I guess, this would then mean this PR will be integrated into mainline after 8th December when the branch for JDK 20 will be forked

Yes, I'm sure this will go in soon after the JDK 20 fork.

[ChrisHegarty]

LGTM

[jddarcy]

Good for JDK 21.

[AlanBateman]

/csr unneeded
/csr needed

[openjdk]

@AlanBateman determined that a CSR request is not needed for this pull request.

[openjdk]

@AlanBateman 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:

8297295: Remove ThreadGroup.allowThreadSuspension

Reviewed-by: jpai, smarks, chegar, darcy

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.

[openjdk]

@AlanBateman has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@AlanBateman please create a CSR request for issue JDK-8297295 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

[jddarcy]

Still looks good.

[AlanBateman]

/integrate

[openjdk]

Going to push as commit d35e840.

[openjdk]

@AlanBateman Pushed as commit d35e840.

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