Python: cross-function threading

Question

Does anyone know a way to acquire a lock so that not only the called function but also other functions are locked.

Let's say I have a bunch of functions ( a(),b(),c() ) an when I call function a() I want also functions b() & c() to be locked.

import threading
from time import sleep

def a():
    for i in range(5):
        print(i)
        sleep(1)

def b():
    for i in range(5):
        print(i)
        sleep(1)

def c():
    for i in range(5):
        print(i)
        sleep(1)

thread_a=threading.Thread(target=a)
thread_a.start()
thread_b=threading.Thread(target=b)
thread_b.start()
thread_c=threading.Thread(target=c)
thread_c.start()

How would I have to use the lock if i wanted the above code to give the output:

0
1
2
3
4
0
1
2
3
4
0
1
2
3
4

?

Any help appreciated, Greetz

Answer 1

You must in a way or another use the same Lock instance shared between your functions.

lock = threading.Lock()

def a():
    with lock:
        for i in range(5):
            print(i)
            sleep(1)

Do this for each function and it will output what you want.