RFR: 8247972: incorrect implementation of JVM TI GetObjectMonitorUsage [v4]

[Serguei Spitsyn]

On Wed, 14 Feb 2024 01:52:16 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Thank you for the comment, David.
>> Now the test checks:
>> - the threads waiting to enter the monitor are returned correctly with all permutations of threads waiting to be notified and threads waiting to re-enter the monitor
>> Initially, there are 4 threads waiting to be notified and zero threads waiting to re-enter the monitor.
>> They are notified one by with the subsequent checks, so all the pairs are checked `<re-enter,wait-for-notif>`: `<0,4>, <1,3>, <2,2>, <3,1>, <4,0>`
>> 
>> I'm not sure why do you think all permutations covering zero and non-zero for each one are needed.
>> At least, it looks like an overkill to me. But if you still think it is really important then I can add cases with zero threads waiting to enter the monitor with the same permutations of threads waiting to be notified and threads re-entering the monitor.
>
> If you don't check all the zero/non-zero permutations for the three counts of interest then you don't know that you are combining them the right way to give the two counts reported by the API.
> Note that checking "all the pairs" is not really necessary as all non-zero values fall in the same equivalence class for testing purposes.

The last suggestion has been addressed by adding missing test cases to the `nsk/jvmti/GetObjectMonitorUsage/objmonusage003` test.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17680#discussion_r1490889210