线程（调用的两种方法、全局变量共享、线程数量）

 1 # -*- coding:utf-8 -*-
 2 # Author:Sure Feng
 3 
 4 
 5 import threading
 6 import time
 7 
 8 
 9 num = 0
10 
11 
12 def sing():
13     # 线程间共享全局变量，可能导致数据混乱
14     global num
15     for i in range(5000):
16         num += 1
17         print("--第【%d】次sing----" % num)
18         # time.sleep(0.1)
19 
20 
21 class Dance(threading.Thread):
22     def run(self):
23         global num
24         for i in range(5000):
25             num += 1
26             print("---第【%d】次dance---" % num)
27             # time.sleep(0.1)
28 
29 
30 def main():
31     # 调用线程的第一种方法
32     t1 = threading.Thread(target=sing)
33     # 调用线程的第二种方法
34     t2 = Dance()
35     t1.start()
36     t2.start()
37 
38     while True:
39         # 查看当前线程数量
40         threading_num = len(threading._enumerate())
41         print("当前的线程数量为%d" % threading_num)
42         if threading_num <= 1:
43             break
44 
45         # time.sleep(0.3)
46 
47 if __name__ == "__main__":
48     main()