Run X processes in background and wait before each of this processes will end.

multiprocessing-demo.py

#!/usr/bin/env python
#
# Run X processes in background and wait before each of this processes will
# end.
#

import sys
import time

from argparse import ArgumentParser
from multiprocessing import Process, Value


DEFAULT_NUMBER = 25


def main():
    parser = ArgumentParser()
    parser.add_argument('number', default=DEFAULT_NUMBER, nargs='?', type=int,
        help='Number of child processes. By default: {}'.\
             format(DEFAULT_NUMBER))

    args = parser.parse_args(sys.argv[1:])
    storage = Value('i', 0)
    processes = []

    print('Start time: {:d}'.format(int(time.time())))
    print

    for i in xrange(args.number):
        process = Process(target=print_and_sleep,
                          args=(storage, i + 1))
        process.start()

        processes.append(process)

    for process in processes:
        process.join()

    print
    print('Total result: {:d}'.format(storage.value))
    print('End time: {:d}'.format(int(time.time())))


def print_and_sleep(storage, number):
    print('    Hello, World! From process #{:d}'.format(number))
    time.sleep(number)
    print('    Bye, World! From process #{:d}'.format(number))
    storage.value += number


if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        print('\n\nOK! OK! Exiting...')