进程 线程（二）

进程锁

为了数据安全

12306售票一个文件{"ticket":1}，有1张票，有10个人过来买票，每个人都看到为1张票，抢票。

# 锁

# 火车票
import json
import time
from multiprocessing import Process
from multiprocessing import Lock

# def show(i):
#     with open('ticket') as f:
#         dic = json.load(f)
#     print('余票: %s'%dic['ticket'])

def buy_ticket(i,lock):
    lock.acquire() #拿钥匙进门
    with open('ticket') as f:
        dic = json.load(f)
        time.sleep(0.1)
    if dic['ticket'] > 0 :
        dic['ticket'] -= 1
        print('\033[32m%s买到票了\033[0m'%i)
    else:
        print('\033[31m%s没买到票\033[0m'%i)
    time.sleep(0.1)
    with open('ticket','w') as f:
        json.dump(dic,f)
    lock.release()      # 还钥匙

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

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