8327501: Common ForkJoinPool prevents class unloading in some cases

[shipilev]

The change is stabilizing in mainline, but it looks simple, so we start testing it for JDK 21 pickup here.

Additional testing:

• Linux x86_64 server fastdebug, all
• Linux AArch64 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/jdk21u-dev.git pull/338/head:pull/338
$ git checkout pull/338

Update a local copy of the PR:
$ git checkout pull/338
$ git pull https://git.openjdk.org/jdk21u-dev.git pull/338/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 338

View PR using the GUI difftool:
$ git pr show -t 338

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u-dev/pull/338.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.

[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

• 03: Full (a5c81e39)
• 02: Full (febeb48b)
• 01: Full - Incremental (f17aeca1)
• 00: Full (bce8bcfc)

[jerboaa]

Lets wait on getting this one backported until the compatibility impact wrt. setting the context class loader of a thread in the common pool is addressed.

[shipilev]

Lets wait on getting this one backported until the compatibility impact wrt. setting the context class loader of a thread in the common pool is addressed.

Yup. With this PR, I just confirmed all tests that I throw at this change pass in jdk21u-dev.

[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 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.

[shipilev]

/issue add JDK-8328366

[openjdk]

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

[shipilev]

Both backports are clean.

/clean

[openjdk]

@shipilev This backport pull request is now marked as clean

[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.

/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]

Lets wait on getting this one backported until the compatibility impact wrt. setting the context class loader of a thread in the common pool is addressed.

Checking, @jerboaa, are you good with this going into jdk21u-dev?

[jerboaa]

@shipilev Yes, though, a bit uneasy. It fixes the unloading issue. We'll have a close look once EA builds are available. Worst case we'll have to back it out during stabilization closer to the 21.0.5 release.

[shipilev]

All right, I am waiting a bit more to see if JDK 23 and 22.0.2 testing finds any issues with it. I plan to integrate this later in July if no issues are found.

[bridgekeeper]

@shipilev This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 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!

[shipilev]

Not now, bot, everything goes according to plan.

[openjdk]

@shipilev Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

[shipilev]

Re-based, re-tested, ready to integrate. Checking with @jerboaa -- go or no-go?

[jerboaa]

Re-based, re-tested, ready to integrate. Checking with @jerboaa -- go or no-go?

@shipilev Please go ahead and integrate it.

[shipilev]

Aye.

/integrate

[openjdk]

Going to push as commit eb103b0.
Since your change was applied there have been 18 commits pushed to the master branch:

• 27b1e1a: 8330146: assert(!_thread->is_in_any_VTMS_transition()) failed
• 27abeb8: 8328642: Convert applet test MouseDraggedOutCauseScrollingTest.html to main
• e4d27d0: 8334618: ubsan: support setting additional ubsan check options
• 953846d: 8333639: ubsan: cppVtables.cpp:81:55: runtime error: index 14 out of bounds for type 'long int [1]'
• fd4ce63: 8322971: KEM.getInstance() should check if a 3rd-party security provider is signed
• d578221: 8335237: ubsan: vtableStubs.hpp is_vtable_stub exclude from ubsan checks
• dac39de: 8333622: ubsan: relocInfo_x86.cpp:101:56: runtime error: pointer index expression with base (-1) overflowed
• 4989165: 8321509: False positive in get_trampoline fast path causes crash
• b79e185: 8331731: ubsan: relocInfo.cpp:155:30: runtime error: applying non-zero offset to null pointer
• ee21571: 8335493: check_gc_overhead_limit should reset SoftRefPolicy::_should_clear_all_soft_refs
• ... and 8 more: https://git.openjdk.org/jdk21u-dev/compare/c2daaa63aba87c801db76478802a87a3bbb326db...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit eb103b0.

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