RFR: 8338714: vmTestbase/nsk/jdb/kill/kill001/kill001.java fails with JTREG_TEST_THREAD_FACTORY=Virtual.

[Serguei Spitsyn]

On Fri, 6 Dec 2024 22:28:29 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

> 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

The fix looks good modulo potential renaming of the `run1()` method.

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PR Review: https://git.openjdk.org/jdk/pull/22620#pullrequestreview-2490055623