On Tue, 25 Apr 2023 21:07:34 GMT, Chris Plummer <cjplum...@openjdk.org> wrote:
> Recently [JDK-8305511](https://bugs.openjdk.org/browse/JDK-8305511) removed > the "@ignore 6951287 ", allowing this test to run, which is why this failure > mode is now turning up. > > There is a race condition, leading to the `popFrames()` call being done while > a native method is in the set of frames to be popped. This results in a > `NativeMethodException` instead of the frames being popped. The debuggee has: > > > public static void waiter() { > if (waiting) { > return; > } > waiting = true; > System.out.println(" debuggee: in waiter"); > while (true) { > } > } > > > And the debugger waits for `waiting == true` (checked via JDI calls) before > suspending and doing the `popFrames()`. The problem is the println() after > setting `waiting = true`. The debugger side can detect that `waiting == true` > before the println() is complete, and the println() involves native code. > Once `waiting` is set true, we need to make sure no other method calls are > made so we can be sure that only the `waiter()` method is on the stack. > > Note there is a lot of interesting history to this CR, including > [JDK-6417053](https://bugs.openjdk.org/browse/JDK-6417053), which actually > reproduced this issue long ago (but got closed as CNR), although it failed > with a different error message (even though it was the same issue), and the > different error message was itself the result of another bug that was > inadvertently fixed when virtual threads support was added to JDI. See the CR > for details if you are interested. Marked as reviewed by lmesnik (Reviewer). ------------- PR Review: https://git.openjdk.org/jdk/pull/13657#pullrequestreview-1400777256
