container.py

import threading
import itertools
from time import sleep
from random import random


def main():
    c = Container(value=0)
    adders = [threading.Thread(target=lambda x: x.add(1), args=(c,))
              for _ in xrange(10000)]
    subers = [threading.Thread(target=lambda x: x.add(-1), args=(c,))
              for _ in xrange(10000)]
    printers = [threading.Thread(target=printer, args=(c,))
                for _ in xrange(5)]
    for thread in itertools.chain(printers, adders, subers):
        thread.start()
    for thread in itertools.chain(adders, subers):
        thread.join()
    print('!!! {} !!!'.format(c.get()))


def printer(x):
        sleep(random())
        print(x.get())


class Container(object):

    def __init__(self, value=None):
        self.value = value
        self.lock = threading.Lock()

    def get(self):
        return self.value

    def set(self, value):
        self.value = value

    def add(self, value):
        with self.lock:
            self.value += value

if __name__ == '__main__':
    main()