A demo script for threading.Condition synchromization primitive.

condition_tut.py

import random, time
from threading import Condition, Thread

# This will be used to represent the availability of a produced item.
condition = Condition()
box = []

def producer(box, nitems):
    for i in range(nitems):
    time.sleep(random.randrange(2, 5)) # Sleeps for some time.
    condition.acquire()
    num = random.randint(1, 10)
    box.append(num) # Puts an item into box for consumption.
    condition.notify() # Notifies the consumer about the availability.
    print(“Produced:”, num)
    condition.release()

def consumer(box, nitems):
    for i in range(nitems):
    condition.acquire()
    condition.wait() # Blocks until an item is available for consumption.
    print(“%s: Acquired: %s” % (time.ctime(), box.pop()))
    condition.release()
  
threads = []
nloops = random.randrange(3, 6) # Number of times an item will be produced and consumed.

for func in [producer, consumer]:
    threads.append(Thread(target=func, args=(box, nloops)))
    threads[-1].start() # Starts the thread.
  
for thread in threads:
    ‘’’
    Waits for the threads to complete before moving on
    with the main script.
    ‘’’
    thread.join()

print(“All done.”)