python进程对象操作-互斥锁问题与解决

多进程下车票购买导致的数据冲突问题

'''
JSON文件 tick_data内容：{"tick_num": 0}
'''

import random
import time
from multiprocessing import Process
import json


def search_ticket(name):
    with open(r'ticket_data', mode='rt', encoding='utf-8') as f:
        ticket_dic = json.load(f)
        print(f'用户{name}查询车票剩余{ticket_dic.get("tick_num")}')


def buy_ticket(name):
    with open(r'ticket_data', mode='r', encoding='utf-8') as f:
        ticket_dic = json.load(f)
        # 模拟网络延迟
        time.sleep(random.randint(1, 3))
        if ticket_dic.get("tick_num") > 0:
            ticket_dic['tick_num'] -= 1
            with open(r'ticket_data', mode='w', encoding='utf-8') as f:
                json.dump(ticket_dic, f)
            print(f'用户{name}购票成功!')
        else:
            print(f'用户{name}购票失败!')


def task(name):
    search_ticket(name)
    buy_ticket(name)


if __name__ == "__main__":
    for i in range(1, 11):
        p = Process(target=task, args=(i,))
        p.start()

通过Lock() 类加锁解决数据冲突问题

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

def search_ticket(name):
    with open(r'ticket_data', mode='rt', encoding='utf-8') as f:
        ticket_dic = json.load(f)
        print(f'用户{name}查询车票剩余{ticket_dic.get("tick_num")}')


def buy_ticket(name,mutex):
    with open(r'ticket_data', mode='r', encoding='utf-8') as f:
        ticket_dic = json.load(f)
        # 模拟网络延迟
        time.sleep(random.randint(1, 3))
        if ticket_dic.get("tick_num") > 0:
            ticket_dic['tick_num'] -= 1
            with open(r'ticket_data', mode='w', encoding='utf-8') as f:
                json.dump(ticket_dic, f)
            print(f'用户{name}购票成功!')
        else:
            print(f'用户{name}购票失败!')


def task(name,mutex):
    search_ticket(name)
    #查票不需要锁，买票时需要用锁控制顺序保证数据安全

    #抢锁
    mutex.acquire()
    buy_ticket(name,mutex)
    #释放锁
    mutex.release()


if __name__ == "__main__":
    mutex = Lock()
    for i in range(1, 11):
        p = Process(target=task, args=(i,mutex))
        p.start()