Thread Based Parallelism - Thread Synchronization With a Condition

 Thread Based Parallelism - Thread Synchronization With a Condition

     from threading import Thread, Condition
     import time

     items = []
     condition = Condition()

     class consumer(Thread):
         def __init__(self):
             Thread.__init__(self)

         def consume(self):
             global condition
             global items

             condition.acquire()
             if len(items) == 0:
                 condition.wait()
                 print("Consumer notify : no item to consume")
             items.pop()
             print("Consumer notify : consumed 1 item")
             print("Consumer notify : items to consume are : " + str(len(items)))
             if len(items) == 0:
                 print("Consumer notify : no items to consume in future")
             condition.notify()
             condition.release()

         def run(self):
             for i in range(0, 10):
                 time.sleep(2)
                 self.consume()

     class producer(Thread):
         def __init__(self):
             Thread.__init__(self)

         def produce(self):
             global condition
             global items

             condition.acquire()
             if len(items) == 4:
                 condition.wait()
                 print("Producer notify : items producted are "  + str(len(items)))
                 print("Producer notify : stop the production!!")
             items.append(1)
             print("Producer notify : total items producted " + str(len(items)))
             condition.notify()
             condition.release()

         def run(self):
             for i in range(0, 10):
                 time.sleep(1)
                 self.produce()

     if __name__ == "__main__":
         producer = producer()
         consumer = consumer()

         producer.start()
         consumer.start()

         producer.join()
         consumer.join()

 Output,
     Producer notify : total items producted 1
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 0
     Consumer notify : no items to consume in future
     Producer notify : total items producted 1
     Producer notify : total items producted 2
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 1
     Producer notify : total items producted 2
     Producer notify : total items producted 3
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 2
     Producer notify : total items producted 3
     Producer notify : total items producted 4
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 3
     Producer notify : total items producted 4
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 3
     Producer notify : items producted are 3
     Producer notify : stop the production!!
     Producer notify : total items producted 4
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 3
     Producer notify : items producted are 3
     Producer notify : stop the production!!
     Producer notify : total items producted 4
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 3
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 2
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 1
     Consumer notify : consumed 1 item
     Consumer notify : items to consume are : 0
     Consumer notify : no items to consume in future