import threading
import time

n = 0
array = [0]*10
sem = threading.Semaphore()

def proc1():
  global n, array
  while True:
    sem.acquire()
    array[n] = n
    n += 1
    sem.release()
    time.sleep(0.25)

def proc2():
  global n, array
  while True:
    sem.acquire()
    array[n] = n
    n += 1
    sem.release()
    time.sleep(0.25)


t = threading.Thread(target = proc1)
t.start()
t2 = threading.Thread(target = proc2)
t2.start()

print (array)