On Thu, 3 Sep 2026 13:56:15 GMT, Jorn Vernee <[email protected]> wrote:
> See the JBS issue for the extended problem description. > > Native threads that were attached to the JVM through an FFM upcall are > automatically detached from the VM when they join/terminate. However, if a > native thread tries to terminate after the VM has exited without going > through `DestroyJavaVm` (e.g. as a result of calling `System.exit`), they > will block in `VM_Exit::block_if_vm_exited` inside `DetachCurrentThread`. > This may happen for instance when they try to join after the JVM has exited > in an `atexit` handler. > > This patch adds a check before trying to detach the thread to see if the VM > has exited and bails out if it has. This does not prevent issues as a result > of a race between the VM exiting and the thread joining, but it does prevent > issues in the more comment case where a thread simply outlives the VM. > > --------- > - [X] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). test/lib/native/testlib_threads.hpp line 46: > 44: } > 45: > 46: class TestThread { I've refactored this helper library (originally written by me) quite a bit to allow starting and joining threads as separate operations. Since this is a C++ library, I've also just removed the `extern "C"` declaration. I think I originally added that when I was trying to make the library usable from C code, but it's currently a header-only library with C++ code, so requires C++ either way. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/32686#discussion_r3935176441
