8293613: need to properly handle and hide tmp VTMS transitions

[sspitsyn]

There are several places in VirtualThread class implementation where virtual threads are being mounted or unmounted, so there is a transition of the JavaThread identity from carrier thread to virtual thread and back. The execution state in such transitions is inconsistent, and so, has to be invisible to JVM TI agents. Such transitions are named as VTMS (virtual thread mount state) transitions, and there is a JVM TI mechanism which supports them. Besides normal VTMS transitions there are also a couple of performance-critical contexts (in VirtualThread methods: scheduleUnpark(), cancel() and unpark()) which can be named as temporary VTMS transitions. Execution state of such temporary VTMS transitions has to be also invisible to the JVM TI agent which is implemented in the current update.

There are a couple of details of this fix to highlight:

• A JavaThread which is in temporary VTMS transition is marked with a special bit _is_in_tmp_VTMS_transition. It is done with the native notification method toggleJvmtiTmpVTMSTrans().
• A couple of lambda form classes can be created in context of temporary VTMS transitions, so their ClassLoad, ClassPrepare and CFLH events are ignored.
• Suspending threads in temporary transition is allowed.

The fix was tested in Loom repository by using JTREG_MAIN_WRAPPER=Virtual mode of execution which forces all main threads to be run as virtual. All JVM TI and JDI tests were run on all platforms. It includes Kitchensink and JCK tests. Additionally, the fix was tested in the jdk 20 repository. It includes JVM TI and JDI tests and tiers 1-6.

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Issue

• JDK-8293613: need to properly handle and hide tmp VTMS transitions

Reviewers

• Chris Plummer (@plummercj - Reviewer)
• Leonid Mesnik (@lmesnik - Reviewer)

Reviewing

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[AlanBateman]

/label remove build

[openjdk]

@AlanBateman
The build label was successfully removed.

[sspitsyn]

Alan is currently investigating and testing his approach to get rid of temporary transitions.
If it comes to be successful then I'll close this PR.
Getting rid of temporary transitions is preferable as it will simplify the code a lot.

However, I've pushed an update to complete my current chunk of work for safety.
It includes two items:

• an update from Alan, to get rid of some lambda form classes loading in context of temporary VTMS transition
• update which address comments from Chris:
  • renaming of Thread class functions
  • changes in the function: JvmtiEnvBase::get_cthread_last_java_vframe()

[openjdk]

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

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

8293613: need to properly handle and hide tmp VTMS transitions

Reviewed-by: cjplummer, lmesnik

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At the time when this comment was updated there had been 138 new commits pushed to the master branch:

• 6ad151d: 8293143: Workaround for JDK-8292217 when doing "step over" of bytecode with unresolved cp reference
• 22b59b6: 8294471: SpecTaglet is inconsistent with SpecTree for inline property
• 763d4bf: 8293592: Remove JVM_StopThread, stillborn, and related cleanup
• 739fdec: 8289162: runtime/NMT/ThreadedMallocTestType.java should print out memory allocations to help debug
• a11477c: 8289797: tools/launcher/I18NArgTest.java fails on Japanese Windows environment
• 7151128: 8294317: Insufficient build rules for tzdb.dat
• fb4979c: 8290401: Support dump all phases and print nodes in ascending order of index
• 112ca2b: 8293964: Unused check_for_duplicates parameter in ClassLoaderExt::process_jar_manifest
• 99017b0: 8293064: Remove unused NET_xxx functions
• 3419363: 8294361: Cleanup usages of StringBuffer in SQLOutputImpl
• ... and 128 more: https://git.openjdk.org/jdk/compare/3beca2db0761f8172614bf1b287b694c8595b498...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.

[sspitsyn]

Thank you for review, Chris!

[sspitsyn]

Thank you for review, Leonid!

[sspitsyn]

/integrate

[openjdk]

Going to push as commit 79ccc79.
Since your change was applied there have been 143 commits pushed to the master branch:

• 5e1e449: 8290920: sspi_bridge.dll not built if BUILD_CRYPTO is false
• d827fd8: 8294430: RISC-V: Small refactoring for movptr_with_offset
• 9d76ac8: 8292158: AES-CTR cipher state corruption with AVX-512
• e5b65c4: 8290482: Update JNI Specification of DestroyJavaVM for better alignment with JLS, JVMS, and Java SE API Specifications
• f8d9fa8: 8294483: Remove vmTestbase/nsk/jvmti/GetThreadState tests.
• 6ad151d: 8293143: Workaround for JDK-8292217 when doing "step over" of bytecode with unresolved cp reference
• 22b59b6: 8294471: SpecTaglet is inconsistent with SpecTree for inline property
• 763d4bf: 8293592: Remove JVM_StopThread, stillborn, and related cleanup
• 739fdec: 8289162: runtime/NMT/ThreadedMallocTestType.java should print out memory allocations to help debug
• a11477c: 8289797: tools/launcher/I18NArgTest.java fails on Japanese Windows environment
• ... and 133 more: https://git.openjdk.org/jdk/compare/3beca2db0761f8172614bf1b287b694c8595b498...master

Your commit was automatically rebased without conflicts.

[openjdk]

@sspitsyn Pushed as commit 79ccc79.

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