Threads with lock

threads_with_lock.py

from time import sleep
from threading import Thread, Lock

counter = 10000

lock = Lock() # Instantiate Python thread lock

def decrease_with_thread_locking(by):
    global counter
    
    # use the lock instance as a context manager
    with lock:
        print(f"Initial Balance: {counter}")
        local_counter = counter
        local_counter -= by
        sleep(1)
        counter = local_counter
        print(f"Updated balance: {counter}")


thread_1 = Thread(target=decrease_with_thread_locking, args=(500,))
thread_2 = Thread(target=decrease_with_thread_locking, args=(500,))
thread_3 = Thread(target=decrease_with_thread_locking, args=(500,))
thread_4 = Thread(target=decrease_with_thread_locking, args=(500,))
thread_5 = Thread(target=decrease_with_thread_locking, args=(500,))
thread_6 = Thread(target=decrease_with_thread_locking, args=(500,))
thread_7 = Thread(target=decrease_with_thread_locking, args=(500,))

thread_1.start()
thread_2.start()
thread_3.start()
thread_4.start()
thread_5.start()
thread_6.start()
thread_7.start()

thread_1.join()
thread_2.join()
thread_3.join()
thread_4.join()
thread_5.join()
thread_6.join()
thread_7.join()


# P.S: Locking can affect performance a little bit as each process trying to work on the same balance need to wait for one process to release the lock before they can acquire it and subsequently complete execution