线程之间共享全局变量存在问题

 1 import time
 2 from threading import*
 3 #定义全局变量num
 4 num = 0
 5 def test1():
 6     global num
 7     for i in range(100000):
 8         num+=1
 9     print('test1输出num:',num)
10 
11 def test2():
12     global num
13     for i in range(100000):
14         num+=1
15     print('test2输出num:',num)
16 
17 if __name__=='__main__':
18     t1 = Thread(target=test1)
19     t2 = Thread(target=test2)
20     t1.start()
21     t2.start()
22     t1.join()
23     t2.join()

1 test1输出num: 100000
2 test2输出num: 146137