Non-blocking back-and-front server cohabitation in Python?

Question

Python

A front server in Python that responds to visitor requests and needs backserver data,
and
a Backserver that regularly collects data on the network, blocking in its thread waiting for answers (synchronous, because responses for requests are needed for the next request)
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actually the question is, how to run them in one environment, from one input file, so that the backserver not only does not block the work of the frontserver, but actually works in parallel?
Multithreads? Multiprocessing? Two runtimes?
How to keep hundreds of MB of backserver data quickly accessible to the frontserver?
I ask for at least a thesis structure for understanding.
RAM on hardware is sufficient.
Front and back in endless loops that don't break.