Thread is not printing properly

Question

I can't seem to bring multithreading to work. I simplified my problem and I still can't get my threads to print properly (so I guess they're not executing correctly).

import time, threading

s_print_lock = threading.Lock()

def s_print(*a, **b):

    with s_print_lock:
        print(*a, **b)
# Thread safe print function

def a():
    while True:
        s_print('\'a\' is running')
        time.sleep(5)
# Thread 1

def b():
    while True:
        s_print('\'b\' is running')
        time.sleep(5)
# Thread 2

if __name__ == "__main__":
    t1 = threading.Thread(target=a())
    t2 = threading.Thread(target=b())

    t1.start()
    t2.start()

And the output is:

'a' is running
'a' is running
'a' is running
'a' is running
...

Answer 1

The target must be a callable. You are executing a() so it's getting in the while True loop and never ending, so never starting the thread. Try this:

if __name__ == "__main__":
    t1 = threading.Thread(target=a)
    t2 = threading.Thread(target=b)

    t1.start()
    t2.start()