multi process version of the prime number counter from https://www.youtube.com/watch?v=hGyJTcdfR1E

search-for-primes.py

import multiprocessing as mp
import time


#max number to look up to
max_number = 10000
#four processes per cpu
num_processes = mp.cpu_count() * 1

def chunks(seq, chunks):
        size = len(seq)
        start = 0
        for i in range(1, chunks + 1):
            stop = i * size // chunks
            yield seq[start:stop]
            start = stop

def calc_primes(numbers):
    num_primes = 0
    primes = []

    #Loop through each number, then through the factors to identify prime numbers
    for candidate_number in numbers:
        found_prime = True
        for div_number in range(2, candidate_number):
            if candidate_number % div_number == 0:
                found_prime = False
                break
        if found_prime:
            primes.append(candidate_number)
            num_primes += 1
    return  num_primes

def main():
    #Record the test start time
    start = time.time()

    pool = mp.Pool(num_processes)

    #0 and 1 are not primes
    parts = [[x] for x in range(1, max_number)]
    #run the calculation
    results = pool.map(calc_primes, parts)
    total_primes = sum(results)

    pool.close()

    #Once all numbers have been searched, stop the timer
    end = round(time.time() - start, 2)

    #Display the results, uncomment the last to list the prime numbers found
    print('Find all primes up to: ' + str(max_number) + ' using ' + str(num_processes) + ' processes.')
    print('Time elasped: ' + str(end) + ' seconds')
    print('Number of primes found ' + str(total_primes))

if __name__ == "__main__":
    main()

Edited following advice from Simon Pratt https://www.youtube.com/watch?v=hGyJTcdfR1E&lc=UgzO5UL2JbefjznbliN4AaABAg.9JMH3io4d6I9JNdFYWmuii

"... changing that line to a simpler parts = [[x] for x in range(1, max_number)] gives much better results. Because we are now loading up the individual cores properly, we also need to change line 8 to remove the * 4, because we can only run one process on each core..."

Hi,
I got your comment notification, but the comment is gone. I'll look into.
It's my first time working with the multiprocess module. The figures my script returns look fine to me and also my cores are all busy when running the script.
I'll look at your differences later this evening.

Thanks for the heads up.

Hi,
I got your comment notification, but the comment is gone. I'll look into.
It's my first time working with the multiprocess module. The figures my script returns look fine to me and also my cores are all busy when running the script.
I'll look at your differences later this evening.

Thanks for the heads up.

So, the changes I made make it use all cores when using a single node.
I can't test it yet when using multiple nodes.