This test fails after [JDK-8338713](https://bugs.openjdk.org/browse/JDK-8338713) when using JTREG_TEST_THREAD_FACTORY=Virtual. The test uses JVMTI StopThread on a thread expecting it to be mounted. Before [JDK-8338713](https://bugs.openjdk.org/browse/JDK-8338713) it would be mounted because it was blocked on a syncrhonized, which resulted in the thread being pinned. After [JDK-8338713](https://bugs.openjdk.org/browse/JDK-8338713) this is no longer the case and the virtual thread has unmounted. This causes JVMTI StopThread to fail with JVMTI_ERROR_OPAQUE_FRAME because it only supports mounted virtual threads.
Fixed by using the VThreadPinner class to make sure the virtual threads remains pinned, and therefore mounted. Testing: - [x] Ran jdb tests locally in both virtual thread mode and platform thread mode. - [ ] tier1 - [ ] tier2 svc - [ ] tier5 svc ------------- Commit messages: - Use VThreadPinner to make sure virtual threads are mounted when StopThread is called. Changes: https://git.openjdk.org/jdk/pull/22620/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22620&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8338714 Stats: 26 lines in 3 files changed: 15 ins; 9 del; 2 mod Patch: https://git.openjdk.org/jdk/pull/22620.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/22620/head:pull/22620 PR: https://git.openjdk.org/jdk/pull/22620
