On Thu, 24 Oct 2024 14:52:27 GMT, Serguei Spitsyn <sspit...@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 incrementally with one
> additional commit since the last revision:
>
> review: removed asserts from continuationFreezeThaw.cpp again
src/hotspot/share/prims/jvmtiEnvBase.cpp line 667:
> 665:
> 666: javaVFrame*
> 667: JvmtiEnvBase::check_and_skip_hidden_frames(bool is_in_VTMS_transition,
> javaVFrame* jvf) {
reworked function looks much better! Now it's clear what the function does and
I have a question what it should do.
The function checks `@JvmtiMountTransition` annotation first even if the thread
is in transition.
If `@JvmtiMountTransition` is present, the code doesn't care about
`@ChangesCurrentThread` (and doesn't case about `@JvmtiMountTransition` if
in_transition + `@ChangesCurrentThread`).
But we have 2 methods in VirtualThread class (`switchToCarrierThread()` and
`switchToVirtualThread()`) with both annotations.
So if the function is called when `switchToCarrierThread` is on top, the
function skips this frame, but if the thread calls some other function without
`@JvmtiMountTransition` annotation from `switchToCarrierThread`, the function
returns `switchToCarrierThread`.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/21397#discussion_r1815790409
