RFR: 8373485: JFR Crash during sampling: assert(jt->has_last_Java_frame()) failed: invariant

[Markus Grönlund]

On Sun, 11 Jan 2026 12:39:06 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

> Greetings,
> 
> When sampling threads in state _thread_in_native, there is a missing memory barrier when UseSystemMemoryBarrier is used, because it must be emitted manually.
> 
> Testing: jdk_jfr
> 
> Thanks
> Markus
> 
> PS "threads_lock" local variable was renamed to "lock" not to confuse with the global Threads_lock.

I am going to have to move (back) the Threads_lock acquisition (as part of https://bugs.openjdk.org/browse/JDK-8373106 to where it was placed originally, before JFR Cooperative Sampling).

Hence, I will update this to exactly mirror the Handshake pattern.

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PR Comment: https://git.openjdk.org/jdk/pull/29155#issuecomment-3738645122