Modern Python Standard Library Cookbook

How to do it...

Pretty much like in the ThreadPool recipe, we will need two functions that will act as our tasks running concurrently in the processes.

In the case of processes, we don't need to perform I/O actually to run concurrently, so our tasks could be doing anything. What I'm going to use is the computing of the Fibonacci series while printing out progress, so that we can see how the output of the two processes will interleave:

import os

def fib(n, seen):
    if n not in seen and n % 5 == 0:
        # Print out only numbers we didn't yet compute
        print(os.getpid(), '->', n)
        seen.add(n)

    if n < 2:
        return n
    return fib(n-2, seen) + fib(n-1, seen)

So, now we need to create the multiprocessing Pool that will run the fib function and spawn computation: ...