Python用上锁和解锁  lock lock.acquire lock.release 模拟抢火车票

import json
import time
from multiprocessing import Process, Lock

# with open('catalogue.json', 'w') as fp:
#     dic = {'total': 3}
#     json.dump(dic, fp)


def check(buyers):
    with open('catalogue.json', mode='r') as fp:
        dic = json.load(fp)
        # print(dic,type(dict))
        print('%s 查询余票：%s' % (buyers, dic['total']))


def buy_tickets(buyers):
    with open('catalogue.json', mode='r') as fp:
        dic = json.load(fp)
    time.sleep(0.8)
    if dic['total'] > 0:
        print('%s 买到票了' % buyers)
        dic['total'] -= 1
        with open('catalogue.json', 'w') as fp:
            json.dump(dic, fp)
    else:
        print('%s 没买到这个票' % buyers)


def ticket_grabbing(buyers, lock):
    check(buyers)
    lock.acquire()
    buy_tickets(buyers)
    lock.release()


if __name__ == '__main__':
    lock = Lock()
    for i in range(10):
        p = Process(target=ticket_grabbing, args =('buyers%s' % i, lock))
        p.start()