python 线程信号量 -5

from atexit import register
from random import randrange
from threading import BoundedSemaphore, Lock, Thread
from time import sleep,ctime

lock = 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()

@register
def _atexit():
    print('all DONE at:', ctime())

if __name__ == '__main__':
    _main()