wait initialized of all threads in pool

Question

I have main thread where I created ThreadPool. Before call function, makes initialization each thread in pool. How wait when all threads will be initialized?

Example:

from multiprocessing.pool import ThreadPool

def main():
    # in main thread
    pool = ThreadPool(processes=5, initializer=init_pool)

    # >>> here it is I want to wait for initialized

    pool.map_async(do_smth).get()

 def init_pool():
    # initialized new thread in pool
    pass

def do_smth():
    # do somethings
    pass

It is necessary not to cause map_async if initialization of a thread exception occurred

I can use Value from multiprocessing for this purpose, but it isn't pretty solution — deniska369, Dec 14 '16 at 13:10

score 2 · Accepted Answer · answered Dec 14 '16 at 14:33

I would implement a barrier in your do_smth()-function and skip the init_pool. But that works only beginning with Python 3.2.

Barriers have a predefined number of parties that have to call the wait-function of the barrier. When the barrier registers the correct number of calls it "drops" and the calling parties return to there their work simultaneously.

Something like that:

from multiprocessing.pool import ThreadPool
from threading import Barrier

b = Barrier(parties=5)

def main():
    # in main thread
    pool = ThreadPool(processes=5)

    pool.map_async(do_smth).get()

def do_smth():
    #initialize here
    b.wait() #call to the barrier
    # do somethings
    pass

Cool, thanks! Despite the fact that I write in Python 2.7, your answer helped me! I can simulate the barrier like this http://stackoverflow.com/a/26703365/4181533 — deniska369, Dec 15 '16 at 07:32

wait initialized of all threads in pool

1 Answers1