进程加锁处理，防止竞争带来的错乱结果

from multiprocessing import Process, Lock
import json
import time
import random
import os


def search():
    time.sleep(0.1)
    with open(‘db.json‘,‘r‘, encoding=‘utf-8‘) as f:
        dic = json.load(f)
        print(‘%s正在查票%s‘%(os.getpid(),dic[‘count‘]))
        return dic[‘count‘]

def get():
    with open(‘db.json‘, ‘r‘, encoding=‘utf-8‘) as f:
        dic = json.load(f)
        if dic[‘count‘] > 0:
            dic[‘count‘] -= 1
            time.sleep(random.randint(1,3))
            with open(‘db.json‘, ‘w‘, encoding=‘utf-8‘) as f:
                json.dump(dic, f)
            print(‘%s 购票成功‘%os.getpid())


def task(lock):
　　##lock.acquire() ###只能一个一个的查看余票数，但是这样做不合理。
    search()        ###并发查票
    lock.acquire()  ###大家可以共同查找网站余票，在同一时间看到的票数相同。  购票的时候抢锁  lock.acquire()
    get()           ###查看完余票之后才能去购票，购票的过程模拟先到先得。不能同时多个人得到同一张余票
    lock.release()  ###

# def task():
#     search()
#     get()

if __name__ == ‘__main__‘:
    lock = Lock()
    for i in range(10):
        p = Process(target=task, args= (lock,))
        # p = Process(target=task)
        p.start()