线程的互斥锁

【一】未加锁会产生的问题

• 所有子线程都会进行阻塞操作，导致最后的改变只是改了一次

from threading import Thread
import time

money = 100


def task():
    global money
    # 模拟获取到车票信息
    temp = money
    # 模拟网络延迟
    time.sleep(2)
    # 模拟购票
    money = temp - 1


def main():
    task_list = [Thread(target=work) for i in range(100)]
    [task.start() for task in task_list]
    [task.join() for task in task_list]
    # 所有子线程结束后打印 money
    print(money)

if __name__ == '__main__':
    main()
    # 99

【二】加锁后

• 在数据发生变化的地方进行加锁处理

from threading import Thread, Lock
import time

money = 100
# 生成锁
mutex = Lock()


def work():
    global money
    # 数据发生改变之前加锁
    mutex.acquire()
    # 模拟获取到车票信息
    temp = money
    # 模拟网络延迟
    time.sleep(0.6)
    # 模拟购票
    money = temp - 1
    # 数据发生改变后解锁
    mutex.release()


def main():
    task_list = [Thread(target=work) for i in range(100)]
    [task.start() for task in task_list]
    [task.join() for task in task_list]
    # 所有子线程结束后打印 money
    print(money)


if __name__ == '__main__':
    main()
    # 0