RFR: 8273617: UninitializedDisplayModeChangeTest.java times out on macOS 12 [v2]

[Phil Race]

On Tue, 28 Sep 2021 10:02:52 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

>> java/awt/FullScreen/UninitializedDisplayModeChangeTest/UninitializedDisplayModeChangeTest.java is timing out every time on macOS 12 even though the test passed.
>> Looks like the the main process waits for child process created in the test forever, making it timeout after jtreg timeout of 2min.
>> Modified to wait for childprocess for 30secs.
>
> Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove thread blocking

If changing waiting to NO doesn't fix the hang, then test would still hang and time out wouldn't it ?
It would be nice to know what *actually happens* on the system with that change.
And if it does fix it .. why ? Could it be a deadlock ? But if so who's and where ?
If the problem is anything like that then a simple native test case may not show it.
But the child process that hangs and does all the display mode changing doesn't create a lot of threads.
And why does it hang and the (several) other tests we have that change display modes etc not hang ?
If you just directly (no jtreg, no parent process) run the child from the command line does it hang ?
Without your updates I mean ..

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PR: https://git.openjdk.java.net/jdk/pull/5647