I've tried to use IOCP with Python and the pywin32 module few years ago. I was never able to make it work, even reading c++ code as a guiding source. Also documentation and resources for IOCP when I looked at the time were very scarce and almost looked like an obscure topic to dive in, and finally gave up. On the other side kqueue and epoll are almost trivial to use. If everything fails there is always select which is easy to use as well.
Making IOCP work underneath stateful protocols like TLS is more complicated still, and then add on multithreaded handlers and things get messy real quick. It’s a similar story with io_uring. It can be done (I’ve done it) but its not easy to reason about (at least for me, maybe I just don’t have the mental horsepower or proper brain wiring to grasp it easily).
