RFR: 8247972: incorrect implementation of JVM TI GetObjectMonitorUsage [v21]

[Serguei Spitsyn]

On Mon, 11 Mar 2024 02:18:57 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> I have an idea how to fix it but it will add extra complexity. Not sure it is worth it.
>> It is possible to identify there was a spurious wakeup and invalidate the sub-test result in such a case.
>> Not sure if it is important to rerun the sub-test then.
>> What do you think?
>
> Sorry I missed this response. I can't see a way to address spurious wakeups in this case as it needs to be a per-thread flag (so that each thread knows it was notified) but you don't know which thread will be notified in any given call to `notify()`. I also can't see how you can detect a spurious wakeup in this code. If they happen then a subtest may fail due to an unexpected number of re-entering threads.
> I think we will just have to see how stable the test is in practice.

Okay, thanks! I'll add some diagnostic code to catch spurious wakups.
Let's see if we ever encounter any spurious wakeup in this test.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/17680#discussion_r1520204046