Using processpool executor in Python3

processpool_executor.py

import concurrent.futures

def test_function(n):
    return n ** 2

# initiate a process pool executor
# by default, number of workers = number of CPU cores 
executor = concurrent.futures.ProcessPoolExecutor(max_workers=10)

# 1. submit jobs to the executor and track in a list
jobs = []
for i in range(10):
    jobs.append(executor.submit(test_function, i))

for future in concurrent.futures.as_completed(jobs):
    result = future.result()
    print(result)
    # do whatever you want to do here:
    # if the exception is thrown from the child fn catch here

# 2. if we want to track the input or other identifier with the result,
# track the submitted jobs to the executor using a dict
jobs = {}
for id in range(10):
    jobs[executor.submit(test_function, id)] = id

for future in concurrent.futures.as_completed(jobs):
    id = jobs[future] # this reflects id above
    result = future.result()
    print(id, result)