RFR: 8341273: JVMTI is not properly hiding some continuation related methods [v8]

[Alan Bateman]

On Tue, 22 Oct 2024 19:16:21 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> This fixes a problem in the VTMS (Virtual Thread Mount State) transition frames hiding mechanism.
>> Please, see a fix description in the first comment.
>> 
>> Testing:
>>  - Verified with new test `vthread/CheckHiddenFrames`
>>  - Mach5 tiers 1-6 are passed
>
> Serguei Spitsyn has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 11 commits:
> 
>  - Merge
>  - review: explain better what methods can be annotated with JvmtiMountTransition
>  - review: clarify the use of annotation @JvmtiMountTransition in yield/yield0
>  - review: moved notifyJvmtiStart/notifyJvmtiEnd calls from VirtualThread.run to the caller
>  - review: tweaked disabler for carrier threads; more hiddenjvmti_mount_transition frames
>  - Disallow NotifyFramePop for enter/enter0/VirtualThread.run/VThreadContinuation.run
>  - review: 1. Minor tweaks in new test; 2. Refactor skip_hidden_frames in two
>  - fix one more place with trailing spaces
>  - fix trailing spaces
>  - add new test coverage with  vthread/CheckHiddenFrames
>  - ... and 1 more: https://git.openjdk.org/jdk/compare/d6eddcda...54dc2b4a

Marked as reviewed by alanb (Reviewer).

src/java.base/share/classes/jdk/internal/vm/annotation/JvmtiMountTransition.java line 32:

> 30: /**
> 31:  * A method may be annotated as "jvmti mount transition" to hint
> 32:  * it is desirable to omit it from JVMTI stack traces.

Might be better to replace both usages of "jvmti mount transition" with JvmtiMountTransition.

"virtual thread mount state transition (VTMS transition)" should probably be "Virtual Thread Mount State (VTMS) transition".

The updated wording is better but I think this still hard to audit to know if you've got the usages in the right place. Maybe we can re-visit it in the future.

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PR Review: https://git.openjdk.org/jdk/pull/21397#pullrequestreview-2387552132
PR Review Comment: https://git.openjdk.org/jdk/pull/21397#discussion_r1812046832