Added important update below
I just discovered something interesting. When closing the kernel from the splash screen, Mathematica hangs.
This is 11.2 running on windows 7 home edition, 64 bit.
These are the steps to reproduce the problem. (1) start mathematica. (2) Click on the new document from the Welcome screen which comes right after M starts. (3). Now close the document just opened using the
Close option. (4) This gets you to the splash screen, which should look like this
(5) open the Evaluation menu that shows on the above screen and select
Quit kernel ->
Now Mathematica hangs. Here is small movie
The task manager shows FE running at full CPU. Only way to recover is to kill the process. I also never see the pop-up message which asks if I really want to kill the local kernel as normally happens. I searched for that pop-up message window and do not see it on the desktop anywhere.
screen shot of task manager
Does this happen to others? This is reproducible for me. I close M many times and get this hangs each time using the above steps. Why does it happen? Is this known issue?
I think what happens is that FE is not able to display the pop-up windows which asks for confirmation of killing the kernel. And that is where it is stuck at.
I think I discovered something important why it hangs. After doing the steps above, and now the FE is hanged, when I simply moved any other application window over on top of the splash screen to cover it, now the pop-up window asking me if I want to really quit the kernel shows up !
This behavior seems to indicate a dynamic problem. Because with dynamics, when one covers it from display, it goes to sleep also.
Here is a movie showing this. Just blocking the splash screen with any other app on the desktop solves this. You can see once I blocked the splash screen, the pop-up menu shows up ! Now I clicked OK and FE no longer hanged.