from atexit import registerfrom random import randrangefrom threading import BoundedSemaphore, Lock, Threadfrom time import sleep,ctimelock = Lock()MAX = 5  # 最大线程数candytray = BoundedSemaphore(MAX)def refill():    lock.acquire()    print('Refilling candy...')    try:        candytray.release()    except ValueError as e:        print('full, skipping', e)    else:        print('ok')    lock.release()def buy():    lock.acquire()    print('Buying candy...')    if candytray.acquire(False):        print('ok')    else:        print('empty, skipping')    lock.release()def producer(loops):    for i in range(loops):        refill()  # 添加        sleep(randrange(3))def consumer(loops):    for i in range(loops):        buy()  # 购买        sleep(randrange(3))def _main():    print('starting at:', ctime())    nloops = randrange(2,6)    print(nloops)    print('THECHADY MACHINE (full with %d bars)!' % MAX)    Thread(target=consumer, args=(randrange(nloops,nloops+MAX+2),)).start() # buyer    Thread(target=producer, args=(nloops,)).start()@registerdef _atexit():    print('all DONE at:', ctime())if __name__ == '__main__':    _main()