只能在linux使用的，win10不能正常运行的

from multiprocessing import cpu_count, Pool, Array, Manager
import numpy as np
N = 20
M = 20
L = 20
ret = Array('f', N*M*L)
def calcul(i, j, k, num,):
    # global ret
    ret._obj[num] = 10.0 #i+j+k
    kk = 0

def main():
    p = Pool(2, initargs=ret)
    num = 0
    for i in range(N):
        for j in range(M):
            for k in range(L):
                # Perform some computations
                # calcul(i, j, k, num)
                p.apply_async(calcul, args=(i, j, k, num,))
                # p.apply(calcul, args=(i, j, k, num,))
                num += 1
    p.close()
    p.join()
    
if __name__=="__main__":
    main()
    kk = []
    for i in range(N*M*L):
        kk.append(ret._obj[i])
    k = 0