多进程抢票加锁

code

# 文件db的内容为：{"count":5}

# 注意一定要用双引号，不然json无法识别

# 并发运行，效率高，但竞争写同一文件，数据写入错乱

from multiprocessing import Process,Lock
import time,json,random
def search():
    dic=json.load(open('db'))
    print('剩余票数%s' %dic['count'])
 
 
def get():
    dic=json.load(open('db'))
    time.sleep(random.random())  # 模拟读数据的网络延迟
    if dic['count'] >0:
        dic['count']-=1
        time.sleep(random.random())  # 模拟写数据的网络延迟
        json.dump(dic,open('db','w'))
        print('购票成功')
    else:
        print('购票失败')
 
 
def task(lock):
    search()
    lock.acquire()
    get()
    lock.release()
 
 
if __name__ == '__main__':
    lock = Lock()
    for i in range(100):  # 模拟并发100个客户端抢票
        p=Process(target=task,args=(lock,))
        p.start()

outputs 

macname@MacdeMacBook-Pro py % python3 cccccc.py
剩余票数2
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购票成功
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购票失败
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macname@MacdeMacBook-Pro py %