Why is the Opencv application hanging?

Question

Python

I created an application for streaming video processing (Windows), I read video, I process it, everything is more or less good, not taking into account periodic cases when img = None. The problem is that the application stops responding, no errors, nothing, the percentage does not load, only 1 MB of memory is added and taken away. And as I noticed, this often happens due to the fact that I remove the focus on this application. What is the reason?

Answer 1

Debugger in hand and look ahead)