8373120: Virtual thread stuck in BLOCKED state

[shipilev]

Fixes another Virtual Thread issue that manifests in JDK 26.

Additional testing:

• New regression test passes; 1000x iterations
• Linux x86_64 server fastdebug, jdk_loom hotspot_loom, 10x
• Linux x86_64 server fastdebug, java/lang/Thread/virtual/stress/, 10x

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Progress

• Change must not contain extraneous whitespace
• JDK-8373120 needs maintainer approval
• Commit message must refer to an issue

Issue

• JDK-8373120: Virtual thread stuck in BLOCKED state (Bug - P3 - Requested)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk26u.git pull/111/head:pull/111
$ git checkout pull/111

Update a local copy of the PR:
$ git checkout pull/111
$ git pull https://git.openjdk.org/jdk26u.git pull/111/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 111

View PR using the GUI difftool:
$ git pr show -t 111

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk26u/pull/111.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back shade! 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]

❗ 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]

⚠️ @shipilev This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (a6fe1f44)

[shipilev]

/approval request Fixes another Virtual Threads issue. This JDK 26 backport is inclusive backport on the way to 25u. Applies cleanly. Stress tests pass. Was in mainline for 1.5 months without bugtail.

[openjdk]

@shipilev
8373120: The approval request has been created successfully.