Python concurrent.futures ProcessPoolExecutor

"""
The ProcessPoolExecutor class is an Executor subclass that uses a pool of processes to execute calls asynchronously. 

ProcessPoolExecutor uses the multiprocessing module
"""

from concurrent.futures import ProcessPoolExecutor
import math
import multiprocessing
import os
import sys
import time

PRIMES = [
    112272535095293,
    112582705942171,
    112272535095293,
    115280095190773,
    115797848077099,
    109972689928541]

def is_prime(n):
    if n == 2:

        return True

    if n % 2 == 0:
        return False

    sqrt_n = int(math.floor(math.sqrt(n)))
    for i in range(3, sqrt_n + 1, 2):
        if n % i == 0:
            return False
    return True

def main():
    print('No of CPUs/Processors: {}' . format(multiprocessing.cpu_count()))
    a = time.time()
    #default max_workers is number of processors on the machine
    with ProcessPoolExecutor() as executor:
        for number, prime in zip(PRIMES, executor.map(is_prime, PRIMES)):
            print('%d is prime: %s' % (number, prime))
    b = time.time()
    print('Time taken: {:.2f} secs'.format(b-a))

if __name__ == '__main__':
    main()


Output:
No of CPUs/Processors: 4
112272535095293 is prime: True
112582705942171 is prime: True
112272535095293 is prime: True
115280095190773 is prime: True
115797848077099 is prime: True
109972689928541 is prime: False
Time taken: 12.67 secs