Python multiprocessing, how not to start a running process?

Question

Python

Is built-in Multiprocessing Python 3
Actually a question. I start one module before I start working with threads. How can I check if a given thread is busy or not? If it is busy, then do not work with it in the right module, where do I start multithreading?
Or how to do it right? If not difficult, with an example, please.