shared_memory.py

import time
from multiprocessing import Process, Value
from multiprocessing import Pool


def sum_numbers(numbers):
    result = 0
    for number in numbers:
        result += number
    return result

def sum_numbers_shared(numbers, shared_sum):
    for number in numbers:
        shared_sum.value += number


if __name__ == '__main__':
    numbers = list(range(1, 100_000))

    start_time = time.time()
    sum_without_multiprocessing = sum_numbers(numbers)
    end_time = time.time()
    print(f'Sum without multiprocessing: {sum_without_multiprocessing}')
    print(f'Time without multiprocessing: {end_time - start_time}')

    shared_sum = Value('i', 0)

    start_time = time.time()
    p = Process(target=sum_numbers_shared, args=(numbers, shared_sum))
    p.start()
    p.join()
    sum_with_shared_memory = shared_sum.value
    end_time = time.time()
    print(f'Sum with shared memory: {sum_with_shared_memory}')
    print(f'Time with shared memory: {end_time - start_time}')


    pool = Pool(processes=4)

    start_time = time.time()
    sum_with_multiprocessing = sum(pool.map(sum_numbers, [numbers[i::4] for i in range(4)]))
    end_time = time.time()
    print(f'Sum with multiprocessing: {sum_with_multiprocessing}')
    print(f'Time with multiprocessing: {end_time - start_time}')