プール

import logging
import multiprocessing
import time

logging.basicConfig(level=logging.DEBUG, format='%(processName)s: %(message)s')


def worker1(i):
    logging.debug('start')
    time.sleep(5)
    logging.debug('end')
    return i


if __name__ == '__main__':
    with multiprocessing.Pool(3) as p:　#3個まで同時にプロセスを実行できる
        logging.debug(p.apply(worker1, (200,))) #値が返ってくるまで次に進まない
        logging.debug('excuted apply')
        p1 = p.apply_async(worker1, (100,)) #非同期なので値が返ってくるのを待たずに次に進む
        p2 = p.apply_async(worker1, (100,)) 
        logging.debug('excuted')
        logging.debug(p1.get())
        logging.debug(p2.get())

ForkPoolWorker-1: start
ForkPoolWorker-1: end
MainProcess: 200
MainProcess: excuted apply
MainProcess: excuted
ForkPoolWorker-2: start
ForkPoolWorker-3: start
ForkPoolWorker-2: end
ForkPoolWorker-3: end
MainProcess: 100
MainProcess: 100