python 多进程买票demo

import threading
import time
num=100
lock=threading.Lock()
#卖票
def sale(name):
    lock.acquire()
    global num
    if num>0:
        num=num-1
        print(name,"卖出一张票，还剩",num,"张！")
    lock.release()

while 1==1:
    if num>0:
        ta=threading.Thread(target=sale,args=("A窗口",))
        tb=threading.Thread(target=sale,args=("B窗口",))
        tc=threading.Thread(target=sale, args=("C窗口",))
        ta.start()
        tb.start()
        tc.start()
        time.sleep(5)
    else:
        break
print("票已卖完！！")