python multiprocessing benchmarks

mp_benchmark.py

"""
Testing python multiprocessing speed. Based on
http://blogs.warwick.ac.uk/dwatkins/entry/benchmarking_parallel_python_1_2/
"""

import time
import math
import multiprocessing as mp

def isprime(n):
    """Returns True if n is prime and False otherwise"""
    if not isinstance(n, int):
        raise TypeError("argument passed to is_prime is not of 'int' type")
    if n < 2:
        return False
    if n == 2:
        return True
    max = int(math.ceil(math.sqrt(n)))
    i = 2
    while i <= max:
        if n % i == 0:
            return False
        i += 1
    return True

def sum_primes(n):
    """Calculates sum of all primes below given integer n"""
    return sum([x for x in xrange(2,n) if isprime(x)])

if __name__=="__main__":
    inputs = range(100000, 1000000, 100000)
    n_cpu = mp.cpu_count()
    pool = mp.Pool(n_cpu)

    print("\nParallel processing with %d cores"%n_cpu)
    start_time = time.time()
    jobs = zip(inputs, pool.map(sum_primes,inputs))
    for input, job in jobs:
        print "Sum of primes below", input, "is", job
    print "Time elapsed: ", time.time() - start_time, "s"

    print("\nSerial processing")
    start_time = time.time()
    for x in inputs:
        print "%d: %d" % (x, sum_primes(x))
    print "Time elapsed: ", time.time() - start_time, "s"

Gitpod
CPU: AMD EPYC 7B13
Arch: x86_64
OS: Linux

Parallel processing with 16 cores
Sum of primes below 100000 is 454396537
Sum of primes below 200000 is 1709600813
Sum of primes below 300000 is 3709507114
Sum of primes below 400000 is 6458901531
Sum of primes below 500000 is 9914236195
Sum of primes below 600000 is 14071826345
Sum of primes below 700000 is 18910286312
Sum of primes below 800000 is 24465663438
Sum of primes below 900000 is 30689332265
Time elapsed: 6.813516616821289 s

Serial processing
100000: 454396537
200000: 1709600813
300000: 3709507114
400000: 6458901531
500000: 9914236195
600000: 14071826345
700000: 18910286312
800000: 24465663438
900000: 30689332265