8268364: jmethod clearing should be done during unloading

[krk]

Backport of 8268364, single hunk conflict resolved by accepting "empty" from the backport commit vs. clear_jmethod_ids invocation in the dtor. Backport commit moves the clear_jmethod_ids invocation to unload method instead.

It fixes crashes when accessing jmethodIDs of a class being unloaded.

Here is the reproducer that crashes JVM in ~1 second without the patch, but works fine with it: gist.

This fix also resolves the issue reported at async-profiler/async-profiler#974 for Java 11.

To run the repro:

javac Main.java
gcc -shared -I"$JAVA_HOME/include" -I"$JAVA_HOME/include/linux" -fPIC repro.cpp -orepro.so

java -agentpath:"$(pwd)/repro.so" -Xmx100m -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -XX:+ExplicitGCInvokesConcurrent Main

---

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
• JDK-8268364 needs maintainer approval

Warning

 ⚠️ Found leading lowercase letter in issue title for 8268364: jmethod clearing should be done during unloading

Issue

• JDK-8268364: jmethod clearing should be done during unloading (Bug - P4 - Approved)

Reviewers

• Coleen Phillimore (@coleenp - Reviewer)

Reviewing

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[bridgekeeper]

👋 Welcome back krk! 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]

@krk This change now passes all automated pre-integration checks.

After integration, the commit message for the final commit will be:

8268364: jmethod clearing should be done during unloading

Reviewed-by: coleenp

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 33 new commits pushed to the master branch:

• 1c80800: 8340552: Harden TzdbZoneRulesCompiler against missing zone names
• 874b25e: 8339637: (tz) Update Timezone Data to 2024b
• 2155f8d: 8339803: Acknowledge case insensitive unambiguous keywords in tzdata files
• c99638d: 8335801: [11u] Backport of 8210988 to 11u removes gcc warnings
• 513a67a: 8303920: Avoid calling out to python in DataDescriptorSignatureMissing test
• cf53387: 8342629: [11u] Properly message out that shenandoah is disabled
• 249144c: 8225045: javax/swing/JInternalFrame/8146321/JInternalFrameIconTest.java fails on linux-x64
• 04e6f37: 8247706: Unintentional use of new Date(year...) with absolute year
• add9000: 8232367: Update Reactive Streams to 1.0.3 -- tests only
• 827528c: 8339470: [17u] More defensive fix for 8163921
• ... and 23 more: https://git.openjdk.org/jdk11u-dev/compare/2232d1f7b497d782edb6fa5f41ec9fd2a90ca33d...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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@coleenp) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[openjdk]

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

[krk]

• MacOS builds are failing for unrelated reason: error: 'sprintf' is deprecated.
• linux-x86 / test - Test (tier1) failing while uploading test artifacts:

Error: Failed to CreateArtifact: Failed to make request after 5 attempts: Request timeout: /twirp/github.actions.results.api.v1.ArtifactService/CreateArtifact

[mlbridge]

Webrevs

• 01: Full - Incremental (032138d9)
• 00: Full (4cc13c48)

[krk]

cc @coleenp @fisk

[coleenp]

This looks like a good backport.

[openjdk]

⚠️ @krk 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.

[krk]

/approval request The fix is required to allow JVM TI tools, especially profilers, run safely with class unloading enabled. Low risk: a small localized change that only affects liveness of jmethodIDs.

[openjdk]

@krk
8268364: The approval request has been created successfully.

[krk]

/approval request All checks passing. The fix is required to allow JVM TI tools, especially profilers, to run safely with class unloading enabled. Low risk: a small localized change that only affects liveness of jmethodIDs.

[openjdk]

@krk
8268364: The approval request has been updated successfully.

[shipilev]

@GoeLin, @jerboaa -- do you see any blockers for approving this?

[jerboaa]

@shipilev JDK 11u is done and only very select fixes will be allowed in going forward. For this one, I'll let @theRealAph handle approval. On the surface it seems OK, but it's another change to a done release which only seems to affect corner cases (profilers when classes get unloaded).

FWIW, SAP stopped work on JDK 11u (11.0.25 was the last one) so you can not expect answers from them for 11u.

[bridgekeeper]

@krk 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!

[jerboaa]

@krk @shipilev Andrew Haley has approved this PR. Do you plan to integrate it?

[krk]

/integrate

[openjdk]

@krk
Your change (at version 032138d) is now ready to be sponsored by a Committer.

[shipilev]

/sponsor

[openjdk]

Going to push as commit 50da3f6.
Since your change was applied there have been 33 commits pushed to the master branch:

• 1c80800: 8340552: Harden TzdbZoneRulesCompiler against missing zone names
• 874b25e: 8339637: (tz) Update Timezone Data to 2024b
• 2155f8d: 8339803: Acknowledge case insensitive unambiguous keywords in tzdata files
• c99638d: 8335801: [11u] Backport of 8210988 to 11u removes gcc warnings
• 513a67a: 8303920: Avoid calling out to python in DataDescriptorSignatureMissing test
• cf53387: 8342629: [11u] Properly message out that shenandoah is disabled
• 249144c: 8225045: javax/swing/JInternalFrame/8146321/JInternalFrameIconTest.java fails on linux-x64
• 04e6f37: 8247706: Unintentional use of new Date(year...) with absolute year
• add9000: 8232367: Update Reactive Streams to 1.0.3 -- tests only
• 827528c: 8339470: [17u] More defensive fix for 8163921
• ... and 23 more: https://git.openjdk.org/jdk11u-dev/compare/2232d1f7b497d782edb6fa5f41ec9fd2a90ca33d...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev @krk Pushed as commit 50da3f6.

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

[gnu-andrew]

@krk @shipilev Andrew Haley has approved this PR. Do you plan to integrate it?

This really should have waited until the rampdown changes were in place. I've manually moved this one to 11.0.27.

[krk]

Sorry for the confusion, thanks for moving it.

[gnu-andrew]

Sorry for the confusion, thanks for moving it.

Thanks. I'm a little late in doing the transition myself with being away at the beginning of the week, but the right version should be used automatically once https://bugs.openjdk.org/browse/JDK-8345509 is integrated. I just thought you should be aware that this will be in the April release. The cut-off for January was Friday.