63_multiprocessing.py

# multiprocessing = running tasks in parallel on different CPU cores, bypasses GIL used for threading
# multiprocessing = better for CPU bound tasks (heavy CPU usage)
# multithreading = better for io bound tasks (waiting around)


from multiprocessing import Process, cpu_count
import time


def counter(num):
    count = 0
    while count < num:
        count += 1


def main():

    print(cpu_count())

    a = Process(target=counter, args=(250000000,))
    b = Process(target=counter, args=(250000000,))
    c = Process(target=counter, args=(250000000,))
    d = Process(target=counter, args=(250000000,))

    a.start()
    b.start()
    c.start()
    d.start()

    a.join()
    b.join()
    c.join()
    d.join()

    start_time = time.time()
    print(start_time)
    print(time.time())
    print("finished in:", time.perf_counter(), "seconds")


if __name__ == '__main__':
    main()