抢票模拟

#!/usr/bin/env python
# encoding: utf-8  
# Date: 2018/6/17
import json, time
from multiprocessing import Process, Lock


def search(name):
    time.sleep(1)  # 模拟网页延迟
    dic = json.load(open('db.txt', 'r', encoding='utf-8'))
    print('<%s>查看剩余票数(%s)' % (name, dic['count']))


def get(name):
    time.sleep(1)
    dic = json.load(open('db.txt', 'r', encoding='utf-8'))
    if dic['count'] > 0:
        dic['count'] -= 1
        time.sleep(3)  # 模拟网络写入数据库，还有支付
        json.dump(dic, open('db.txt', 'w', encoding='utf-8'))
        print('<%s> 购票成功' % name)


def task(name, mutex):
    search(name)  # 查票应该是并发执行
    mutex.acquire()
    get(name)  # 购票应该是串行
    mutex.release()


if __name__ == '__main__':
    mutex = Lock()  # 互斥锁
    for i in range(10):  # 模拟是个人抢票
        p = Process(target=task, args=('路人%s' % i, mutex))
        p.start()

　　#  p.join()  # 会把看都变成串行，代码整体受影响

        
db.txt
{"count": 1}