8327501: Common ForkJoinPool prevents class unloading in some cases

[shipilev]

First change fixes the regression since JDK 19. Second change fixes the regression from the fix.

Additional testing:

• Linux x86_64 server fastdebug, all

---

Progress

• JDK-8327501 needs maintainer approval
• JDK-8328366 needs maintainer approval
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issues

• JDK-8327501: Common ForkJoinPool prevents class unloading in some cases (Bug - P4 - Approved)
• JDK-8328366: Thread.setContextClassloader from thread in FJP commonPool task no longer works after JDK-8327501 (Bug - P3 - Approved)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk22u.git pull/206/head:pull/206
$ git checkout pull/206

Update a local copy of the PR:
$ git checkout pull/206
$ git pull https://git.openjdk.org/jdk22u.git pull/206/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 206

View PR using the GUI difftool:
$ git pr show -t 206

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk22u/pull/206.diff

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.

[shipilev]

/issue add JDK-8328366
/clean

Both backports are clean.

[openjdk]

@shipilev 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:

8327501: Common ForkJoinPool prevents class unloading in some cases
8328366: Thread.setContextClassloader from thread in FJP commonPool task no longer works after JDK-8327501

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 18 new commits pushed to the master branch:

• 5a659b7: 8326446: The User and System of jdk.CPULoad on Apple M1 are inaccurate
• e32e05b: 8329840: Fix ZPhysicalMemorySegment::_end type
• a3e51ec: 8329109: Threads::print_on() tries to print CPU time for terminated GC threads
• ae8dae9: 8325587: Shenandoah: ShenandoahLock should allow blocking in VM
• b0cd610: 8332253: Linux arm32 build fails after 8292591
• 4541823: 8329605: hs errfile generic events - move memory protections and nmethod flushes to separate sections
• f539469: 8330464: hserr generic events - add entry for the before_exit calls
• da980f9: 8331031: unify os::dont_yield and os::naked_yield across Posix platforms
• 1e173f9: 8330814: Cleanups for KeepAliveCache tests
• 9836209: 8261433: Better pkcs11 performance for libpkcs11:C_EncryptInit/libpkcs11:C_DecryptInit
• ... and 8 more: https://git.openjdk.org/jdk22u/compare/c3e90844a72cf79cbc7dc5fe6ee234839d0b4f2b...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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[openjdk]

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

[openjdk]

@shipilev
Adding additional issue to issue list: 8328366: Thread.setContextClassloader from thread in FJP commonPool task no longer works after JDK-8327501.

[openjdk]

@shipilev This backport pull request is now marked as clean

[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 (8c5fd61f)

[shipilev]

/approval 8327501 request Fixes the class unloading regression since JDK 19. Applies cleanly. Tests pass, but there is a regression, which is fixed by JDK-8328366. Risk is medium: affects common paths, has bugtail with easily detectable failures. Doing this patch in 22.0.2 exposes the fix to larger group of users, paving the way to 21u backport.

/approval 8328366 request Fixes the regression introduced by JDK-8327501. Applies cleanly. Tests pass.

[openjdk]

@shipilev
8327501: The approval request has been created successfully.

[openjdk]

@shipilev
8328366: The approval request has been created successfully.

[shipilev]

/integrate

[openjdk]

Going to push as commit 3663b2d.
Since your change was applied there have been 19 commits pushed to the master branch:

• b96b4f6: 8332490: JMH org.openjdk.bench.java.util.zip.InflaterInputStreams.inflaterInputStreamRead OOM
• 5a659b7: 8326446: The User and System of jdk.CPULoad on Apple M1 are inaccurate
• e32e05b: 8329840: Fix ZPhysicalMemorySegment::_end type
• a3e51ec: 8329109: Threads::print_on() tries to print CPU time for terminated GC threads
• ae8dae9: 8325587: Shenandoah: ShenandoahLock should allow blocking in VM
• b0cd610: 8332253: Linux arm32 build fails after 8292591
• 4541823: 8329605: hs errfile generic events - move memory protections and nmethod flushes to separate sections
• f539469: 8330464: hserr generic events - add entry for the before_exit calls
• da980f9: 8331031: unify os::dont_yield and os::naked_yield across Posix platforms
• 1e173f9: 8330814: Cleanups for KeepAliveCache tests
• ... and 9 more: https://git.openjdk.org/jdk22u/compare/c3e90844a72cf79cbc7dc5fe6ee234839d0b4f2b...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit 3663b2d.

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