import torch
from multiprocessing import Pool as ThreadPool

global_array = torch.rand(100000)
numbers = torch.rand(4)

# function called at each iteration
def my_subtractor(number, verbose=True):
    if verbose:
        print("SHOULD PRINT 4 TIMES") # -- prints for every worker in the pool (so 4 times total)
    global_array - number
    return 0

# launch for loop
for number in numbers:
    my_subtractor(number, verbose=False)

# launch equivalent pool of workers
pool = ThreadPool(2)
pool.map(my_subtractor, numbers)