网络编程-线程-5、多个线程共享全局变量造成资源争抢，数据混乱

#!/usr/bin/env python
# coding=utf-8
# author:刘仲
# datetime:2018/7/23 14:18
# software: PyCharm

import threading
import time

num = 0
# 线程函数1修改num值，循环一百万次，每次加一，理论上num结果为1000000
def test1(temp):
    global num
    for i in range(temp):
        num += 1
    print('test1-num:%d' % num)

# 线程函数2修改num值，也是循环一百万次，每次加一，理论上test1执行完后，此时test2num结果为2000000
def test2(temp):
    global num
    for i in range(temp):
        num += 1
    print('test2-num:%d' % num)

def main():
    t1 = threading.Thread(target=test1, args=(1000000,))
    t2 = threading.Thread(target=test2, args=(1000000,))
    t1.start()
    t2.start()
    time.sleep(1)
    print('num:%d' % num)


if __name__ == '__main__':
    main()

运行效果如下：
test1-num:1255312
test2-num:1319790
num:1319790