ejercicio3.py

#!/usr/bin/env python

import threading


PRODUCTS = 5
CONSUMERS = 7


def use_screen(message):
    screen.acquire()
    print message
    screen.release()


class Producer(threading.Thread):

    def __init__(self, name='Yo'):
        threading.Thread.__init__(self)
        self.name = name

    def run(self):
        for item in xrange(1, PRODUCTS):
            context['empty_buffer'].acquire()
            context['item'] = "Item " + str(item)
            use_screen(context['item'] + " delivered.")
            context['full_buffer'].release()


class Consumer(threading.Thread):

    def __init__(self, name='Yo'):
        threading.Thread.__init__(self)
        self.name = name

    def run(self):
        for time in xrange(1, PRODUCTS):
            context['full_buffer'].acquire()
            if context['consumed'] < CONSUMERS - 1:
                use_screen(
                    "I'm consumer [" + str(self.name) + "] reading " +
                    context['item'])
                context['consumed'] += 1
                context['full_buffer'].release()
                context['barrier'].acquire()
            else:
                context['consumed'] = 1
                context['empty_buffer'].release()
                for each in xrange(0, CONSUMERS):
                    context['barrier'].release()


if __name__ == "__main__":
    context = {
        'barrier': threading.Semaphore(0),
        'consumed': 1,
        'full_buffer': threading.Semaphore(0),
        'empty_buffer': threading.Semaphore()
    }

    screen = threading.Semaphore()
    prod = Producer('prod')
    consumers = [Consumer(pid) for pid in xrange(1, CONSUMERS)]

    prod.start()
    for consumer in consumers:
        consumer.start()