Is this the right way to use multiprocessing queue with python?

Question

I am trying to speed up my code by using multiprocessing with Python. The only problem I ran into when trying to implement multiprocessing was that my function has a return statement and I needed to save that data to a list. The best way I found using google was to use queue as "q.put()" and retrieve it using "q.get()". The only issue is that I think i'm not utilizing this the right way because when I use command prompt after compiling, it shows i'm hardly using my cpu and I only see one Python process running. If I remove "q.get()" the process is super fast and utilizes my cpu. Am I doing this the right way?

import time
import numpy as np
import pandas as pd
import multiprocessing 
from multiprocessing import Process, Queue


def test(x,y,q):

    q.put(x * y)


if __name__ == '__main__':

    q = Queue()

    one = []
    two = []
    three = []

    start_time = time.time()


    for x in np.arange(30, 60, 1):
        for y in np.arange(0.01, 2, 0.5):

            p = multiprocessing.Process(target=test, args=(x, y, q))
            p.start()
            one.append(q.get())
            two.append(int(x))
            three.append(float(y))
            print(x, ' | ', y, ' | ', one[-1])

    p.join()

    print("--- %s seconds ---" % (time.time() - start_time))

    d = {'x' : one, 'y': two, 'q' : three}
    data = pd.DataFrame(d)
    print(data.tail())

Answer 1

No, this is not correct. You start a process and wait for the result through q.get at once. Therefore only one process running at the same time. If you want to operate on many tasks, use multiprocessing.Pool :

import time
import numpy as np
from multiprocessing import Pool
from itertools import product

def test((x,y)):
    return x, y, x * y

def main():
    start_time = time.time()
    pool = Pool()
    result = pool.map(test, product(np.arange(30, 60, 1), np.arange(0.01, 2, 0.5)))
    pool.close()
    print("--- %s seconds ---" % (time.time() - start_time))
    print(result)

if __name__ == '__main__':
    main()