import time import threading begin = False def numCounter(): num = 60 global begin while True: if begin: num = num -1 print(f'num={num}, begin={begin}') time.sleep(1) if num<=0: num = 60 else: pass def keyDectect(): # TODO:need to be revised by using the threading lock global begin while True: key = input() if key == 'b': begin = True elif key == 't': begin = False else: print('wrong input..') if __name__ == '__main__': t1 = threading.Thread(target=numCounter) t2 = threading.Thread(target=keyDectect) t1.setDaemon(False) t2.setDaemon(False) t1.start() t2.start()