Python multiprocessing - values not appending to the list and the processes remain stuck

Asked Dec 26 '18 at 16:48

Active Dec 26 '18 at 16:48

Viewed 54 times

My function:

value1 = []
value2 = []
def func_test(x):
    time.sleep(0.5)
    value1.append(x**3)
    value2.append(x+1)

The goal is to use the processor pools to parallely append values to the lists.

Here's what I did:

pool = mp.Pool(processes=4)
pool.map(func_test, [1,2,3,4,5])

The processes stays stuck. I am assuming it is probably because of deadlock. Is there any way to resolve this?

asked Dec 26 '18 at 16:48

sjishan

Your code should work as calling `append()` on a list is thread safe. Are you sure it's stuck? Your sleep calls will mean it should take a couple seconds. – Micah Carrick Dec 26 '18 at 16:55
using windows? https://stackoverflow.com/questions/32995897/python-multiprocessing-pool-hangs-on-map-call – Jean-François Fabre Dec 26 '18 at 17:00
@MicahCarrick stuck over 5 minutes – sjishan Dec 26 '18 at 17:18
@Jean-FrançoisFabre ubuntu. but thaniks. – sjishan Dec 26 '18 at 17:18
Can you post the entire code? – Micah Carrick Dec 26 '18 at 17:25
1

Also, are you running a script or doing this in the interactive interpreter? Multiprocessing won't play nice with the interactive interpreter. – Micah Carrick Dec 26 '18 at 18:06

0 Answers0