On Tue, 27 Jan 2026 01:48:03 GMT, Serguei Spitsyn <[email protected]> wrote:
> The `interp-only` mechanism is based on the `JavaThread` objects. Carrier and > virtual threads can temporary share the same `JavaThread`. The > `java_thread->jvmti_thread_state()` is re-linked to a virtual thread at > `mount` and to the carrier thread at `unmount`. The `JvmtiThreadState` has a > back link to the `JavaThread` which is also set for virtual thread at a > `mount` and carrier thread at an `unmount`. Just one of these two links at > the same time is set to the `JavaThread`, the other one has to be set to > `nullptr`. The `interp-only` mechanism needs this invariant. > However, there is a corner case when this invariant is broken. It happens > when the `JvmtiThreadState` for carrier thread has just been created. In such > case, the link to `JavaThread` is always `non-nullptr` even though a virtual > thread is currently mounted on a carrier thread. This simple update fixes the > issue in the `JvmtiThreadState` ctor. > > Also, this update the includes the `interp_only` implementation > simplifications and more asserts are added to relevant places. One of the > simplification is a removal of the field `JvmtiThreadState::_thread_saved`. > > Testing: > - TBD: Mach5 tiers 1-6 This pull request has now been integrated. Changeset: dc06fede Author: Serguei Spitsyn <[email protected]> URL: https://git.openjdk.org/jdk/commit/dc06fede2af2f10011695b0539b6f4d2cb1f07df Stats: 81 lines in 7 files changed: 29 ins; 20 del; 32 mod 8373367: interp-only mechanism fails to work for carrier threads in a corner case Reviewed-by: amenkov, lmesnik ------------- PR: https://git.openjdk.org/jdk/pull/29436
