[klibertp]

> Can we avoid the overhead of starting and shutting down processes by running a single Python process and communicating using something like grpc

Actually, that's how ErlPort works. You start a Python process and then you call some functions inside that process. How many functions you'd like to run using a single Python process is up to you - you can spawn a new worker for every call or spawn only one worker and stick to it unless it's killed somehow.

You can also register callbacks on either side (Elixir or Python) and with a bit more effort you can make Python process accept normal Elixir messages and answer in the same way.

> How do web frameworks like Flask handle multiple concurrent requests?

In my experience, they mostly rely on uWSGI and a pool of processes...