Python 多线程

 1 import threading    # 封装了thread模块
 2 import time
 3 
 4 
 5 def foo(k):
 6     time.sleep(1)
 7     print("%s now running : %s" % (k, threading.current_thread().name))
 8 
 9 
10 if __name__ == "__main__":
11     print("now running: ", threading.current_thread().name)  
12     thread_list = []    # 这里我们创建一个列表用于存放创建的子线程对象
13     for i in range(5):
14         t = threading.Thread(target=foo, args=(i, ))    # 创建线程对象t
15         thread_list.append(t)
16 
17     for t in thread_list:
18         t.start()
19 
20 
21 # 第一次执行：
22     # now running: MainThread
23     # main thread end !      time used: 0.001002   #  主线程耗时极短 
24     # 1 now running : Thread-2
25     # 2 now running : Thread-3
26     # 0 now running : Thread-1
27     # 4 now running : Thread-5
28     # 3 now running : Thread-4
29 
30 # 第二次执行：
31     # now running: MainThread
32     # main thread end !      time used: 0.001970
33     # 1 now running : Thread-2
34     # 0 now running : Thread-1
35     # 4 now running : Thread-5
36     # 3 now running : Thread-4
37     # 2 now running : Thread-3
38     # 实现了并发的效果， 并且可以看出， 主线程开了之后， 主线程、子线程各自执行直至程序执行结束。 其实， 在子线程结束前，主线程依旧存在。

 1 # 现对线程的执行部分（以上17-18行）做个修改
 2      for t in thread_list:
 3          t.start()
 4          t.join()  # join后所join的线程执行完才能执行下一个线程
 5  
 6  # 加入join后，执行结果
 7      # now running:  MainThread
 8      # 0 now running : Thread-1
 9      # 1 now running : Thread-2
10      # 2 now running : Thread-3
11      # 3 now running : Thread-4
12      # 4 now running : Thread-5
13      # main thread end !      time used: 5.004852

 1 import threading   
 2 import time
 3 
 4 
 5 def foo():
 6     time.sleep(1)
 7     print("now running : %s" %  threading.current_thread().name)
 8 
 9 
10 if __name__ == "__main__":
11     print("now running: ", threading.current_thread().name)
12     start = time.time()
13     t = threading.Thread(target=foo))
14     # t.setDaemon(True)
15     t.start()
16     end = time.time()
17     print("main thread end ! \t time used: %f" % (end - start))
18     
19     # 以下为输出结果：
20 
21     # now running:  MainThread
22     # main thread end !      time used: 0.000974
23     # 1 now running : Thread-1
24 
25 
26     # t.setDaemon(True)执行后：
27 
28     # now running:  MainThread
29     # main thread end !      time used: 0.001004
30     # 线程t未完全执行
31