JDK-8272065: jcmd cannot rely on the old core reflection implementation which will be changed after JEP 416

[tstuefe]

VM.metaspace, VM.classloaders and VM.class_hierarchy all print out reflection invocation targets for delegating reflection class loaders. Post JEP 416 we don't use DelegatingClassLoaders anymore.

This patch removes the display of reflection targets from these commands as well as associated helper code and tests.

I don't have enough time atm to reimplement this feature using method handles. But at least we can remove the old code, and prepare the way for more code removal.

The patch does not touch vmClasses, reflect_ConstructorAccessor and reflect_MethodAccessor are both still there.

Tests: GHAs, manually testing the commands.

---

Progress

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Issue

• JDK-8272065: jcmd cannot rely on the old core reflection implementation which will be changed after JEP 416

Reviewers

• Mandy Chung (@mlchung - Reviewer)
• Coleen Phillimore (@coleenp - Reviewer)
• David Holmes (@dholmes-ora - Reviewer)

Reviewing

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[mlbridge]

Webrevs

• 00: Full (c1ba707d)

[mlchung]

Looks good to me. Thanks for following this up. The new implementation does not spin any new class loader and so I don't think jcmd needs to extend its support for the new implementation using method handles.

[openjdk]

@tstuefe 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:

8272065: jcmd cannot rely on the old core reflection implementation which will be changed after JEP 416

Reviewed-by: mchung, coleenp, dholmes

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 27 new commits pushed to the master branch:

• 8e17ce0: 8275185: Remove dead code and clean up jvmstat LocalVmManager
• 396132f: 8275509: ModuleDescriptor.hashCode isn't reproducible across builds
• 9ad4d3d: 8276025: Hotspot's libsvml.so may conflict with user dependency
• e21b5c7: 8276650: GenGraphs does not produce deterministic output
• 7b1916e: 8233557: [TESTBUG] DoubleClickTitleBarTest.java fails on macOs
• 8ec80c4: 8276653: Missing row headers in j.l.Character docs
• 7e87f94: 8276652: Missing row headers in MethodHandles.Lookup docs
• dcf36f8: 8275670: ciReplay: java.lang.NoClassDefFoundError when trying to load java/lang/invoke/LambdaForm$MH
• 81203ef: 8276655: Use blessed modifier order in SCTP
• 2b5a32c: 8275718: Relax memory constraint on exception counter updates
• ... and 17 more: https://git.openjdk.java.net/jdk/compare/558ee40a4ac158e5be8269c87b7e18af77dd14c5...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.

[tstuefe]

Looks good to me. Thanks for following this up. The new implementation does not spin any new class loader and so I don't think jcmd needs to extend its support for the new implementation using method handles.

Thank you Mandy!

[coleenp]

Yes, looks good to me also.

[dholmes-ora]

I never realized we needed special handling for these classloaders so I'm glad to see this gone too.

Thanks,
David

[tstuefe]

Thanks @mlchung, @coleenp and @dholmes-ora.

/integrate

[openjdk]

Going to push as commit 7281861.
Since your change was applied there have been 27 commits pushed to the master branch:

• 8e17ce0: 8275185: Remove dead code and clean up jvmstat LocalVmManager
• 396132f: 8275509: ModuleDescriptor.hashCode isn't reproducible across builds
• 9ad4d3d: 8276025: Hotspot's libsvml.so may conflict with user dependency
• e21b5c7: 8276650: GenGraphs does not produce deterministic output
• 7b1916e: 8233557: [TESTBUG] DoubleClickTitleBarTest.java fails on macOs
• 8ec80c4: 8276653: Missing row headers in j.l.Character docs
• 7e87f94: 8276652: Missing row headers in MethodHandles.Lookup docs
• dcf36f8: 8275670: ciReplay: java.lang.NoClassDefFoundError when trying to load java/lang/invoke/LambdaForm$MH
• 81203ef: 8276655: Use blessed modifier order in SCTP
• 2b5a32c: 8275718: Relax memory constraint on exception counter updates
• ... and 17 more: https://git.openjdk.java.net/jdk/compare/558ee40a4ac158e5be8269c87b7e18af77dd14c5...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tstuefe Pushed as commit 7281861.

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