A demo script for threading.Lock

lock_tut.py

from threading import Lock, Thread
lock = Lock()
g = 0

def add_one():
   global g # Just used for demonstration. It’s bad to use the ‘global’ statement in general.
   lock.acquire()
   g += 1
   lock.release()

def add_two():
   global g
   lock.acquire()
   g += 2
   lock.release()

threads = []
for func in [add_one, add_two]:
   threads.append(Thread(target=func))
   threads[-1].start()

for thread in threads: # Waits for threads to complete before moving on with the main script.
   thread.join()

print(g)