守護線程：只起到守護主線程的作用，主線程退出守護線程也跟著退出。

 1 import threading,time
 2 
 3 def run(n):
 4     print("task",n)
 5     time.sleep(2)
 6     print("task done",n)
 7 
 8 start_time = time.time()
 9 t_objs =  []
10 for i in range(50):
11     t = threading.Thread(target=run,args=("t-%s"%i,))
12     t.setDaemon(True)#
 
把當前線程設置為守護線程
13     t.start()
14     t_objs.append(t)#為了不阻塞後面線程的啟動，不在這裏join,先放到一個列表裏
15 
16 # for t in t_objs:#循環線程實例列表，等待所有線程執行完畢
17 #     t.join()
18 
19 print("------all threads has finished....",threading.current_thread(),)
20 print("cost:",time.time()-start_time)
21 
22     # t1 = threading.Thread(target=run,args=("t1",))
 

23     # t2 = threading.Thread(target=run,args=("t2",))
24     # t1.start()
25     # t2.start()
26 
27 # run("t1")
28 # run("t2")

Python學習之路：守護線程