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multi process version of the prime number counter from https://www.youtube.com/watch?v=hGyJTcdfR1E
import multiprocessing as mp
import time
#max number to look up to
max_number = 10000
#four processes per cpu
num_processes = mp.cpu_count() * 4
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 = chunks(range(2, max_number, 1), 1)
#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()
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