A demo script for threading.Event synchronization primitive

event_tut.py

import random, time
from threading import Event, Thread

event = Event()

def waiter(event, nloops):
    for i in range(nloops):
    print(“%s. Waiting for the flag to be set.” % (i+1))
    event.wait() # Blocks until the flag becomes true.
    print(“Wait complete at:”, time.ctime())
    event.clear() # Resets the flag.
    print()

def setter(event, nloops):
    for i in range(nloops):
    time.sleep(random.randrange(2, 5)) # Sleeps for some time.
    event.set()

threads = []
nloops = random.randrange(3, 6)

threads.append(Thread(target=waiter, args=(event, nloops)))
threads[-1].start()
threads.append(Thread(target=setter, args=(event, nloops)))
threads[-1].start()

for thread in threads:
    thread.join()

print(“All done.”)