8350765: Need to pin when accessing thread container from virtual thread

[AlanBateman]

Data structures that are accessed by both virtual threads and their carriers require the virtual thread to pin the continuation to avoid potential deadlock. A deadlock can arise when a virtual thread is preempted, is selected and scheduled to be the next owner of the lock/resource, but can't execute because all carriers are blocking on the same lock/resource. There are a small number of places that need to pin. One that was missed is the the notification to the thread container when threads are started or terminate. This is not currently an issue at this time but it is a potential hazard for ongoing and future work that will add further scheduling points to the code. Continuation.pin/unpin have intrinsics since JDK-8338745, and Continuation is initialized early in startup. Finally, the changes have been in the loom repo for several months with no issues.

Testing tier1-5, quick statup/footprint, noreg-hard

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Progress

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Issue

• JDK-8350765: Need to pin when accessing thread container from virtual thread (Bug - P4)

Reviewers

• Viktor Klang (@viktorklang-ora - Reviewer)
• Jaikiran Pai (@jaikiran - Reviewer)

Reviewing

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[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 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:

8350765: Need to pin when accessing thread container from virtual thread

Reviewed-by: vklang, jpai

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At the time when this comment was updated there had been 28 new commits pushed to the master branch:

• 48d2acb: 8356783: CompilerTask hot_method is redundant
• de10644: 8356631: OopHandle replacement methods should not be called on empty handles
• 14d372b: 8356816: JFR: Move printing of metadata into separate class
• ... and 25 more: https://git.openjdk.org/jdk/compare/7ae52ce572794f9d17446c66381f703ea1bb8b7c...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.

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[openjdk]

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[bridgekeeper]

@AlanBateman This pull request has been inactive for more than 8 weeks and will be automatically closed if another 8 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[viktorklang-ora]

Nice work, Alan

[mlbridge]

Webrevs

• 01: Full - Incremental (5ff93aea)
• 00: Full (2959e070)

[jaikiran]

Thank you for the update Alan. The change looks reasonable to me.

[viktorklang-ora]

Nice work, Alan!

[AlanBateman]

/integrate

[openjdk]

Going to push as commit fa41948.
Since your change was applied there have been 28 commits pushed to the master branch:

• 48d2acb: 8356783: CompilerTask hot_method is redundant
• de10644: 8356631: OopHandle replacement methods should not be called on empty handles
• 14d372b: 8356816: JFR: Move printing of metadata into separate class
• ... and 25 more: https://git.openjdk.org/jdk/compare/7ae52ce572794f9d17446c66381f703ea1bb8b7c...master

Your commit was automatically rebased without conflicts.

[openjdk]

@AlanBateman Pushed as commit fa41948.

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