[Python] Getting started with multithreading

Original: http://blog.csdn.net/ice110956/article/details/28421807

There are two ways to implement multithreading in Python:

function, Thread class

1. Functions

Call the Start_new_thread () function in the thread module to create a thread that tells the thread what to do in the form of a thread function

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2. #-*-Coding:utf-8-*-
4. Import Thread
10. def f (name):
12. #定义线程函数
14. Print "This is" + name
20. if __name__ = = ' __main__ ':
22. Thread.start_new_thread (F, ("Thread1",))
24. #用start_new_thread () calling thread functions and other parameters
26. while 1:
28. Pass

However, this method has not been able to find other auxiliary methods, even the main thread waits to use while 1 this method to solve.

2. Threading Class

Call the threading module to create the threading. The subclass of thread to get the custom thread class.

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2. #-*-Coding:utf-8-*-
4. Import threading
10. Class Th (threading. Thread):
12. def __init__ (self, name):
14. Threading. Thread.__init__ (self)
16. self.t_name = name
18. #调用父类构造函数
22. def run (self):
24. #重写run () function, the thread starts execution from this function by default
26. Print "This is" + self.t_name
30. if __name__ = = ' __main__ ':
32. Thread1 = Th ("Thread_1")
34. Thread1.start ()
36. #start () function starts the thread and executes the run () function automatically

Threading. Inheritable functions for the thread class:

GetName () Gets the thread object name

SetName () Set Thread object name

Join () wait for the calling thread to end before running the command

Setdaemon (BOOL) blocking mode, True: Parent thread does not wait for child threads to end, false waits, default is False

Isdaemon () Determines whether the child thread ends with the parent thread, that is, the value set by the Setdaemon ()

IsAlive () Determine if the thread is running

Instance

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2. Import threading
4. Import time
10. Class Th (threading. Thread):
12. def __init__ (self, thread_name):
14. Threading. Thread.__init__ (self)
16. self.setname (thread_name)
20. def run (self):
22. Print "This is thread" + self.getname ()
24. For I in range (5):
26. Time.sleep (1)
28. Print str (i)
30. print self.getname () + " is Over"

Join () Blocking wait

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1. if __name__ = = ' __main__ ':
2. Thread1 = Th ("T1")
3. Thread1.start ()
4. #thread1. Join ()
5. print "main thread is over"

Without Thread1.join (), the following results are obtained:

This is thread T1

Main thread is over

0

1

2

T1 is Over

Do not wait for Thread1 to complete after executing the statement.

Add Thread1.join () to get the following result:

This is thread T1

0

1

2

T1 is Over

Main thread is over

Blocking waits for thread1 to end before executing the following statement

Main thread Wait

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1. if __name__ = = ' __main__ ':
2. Thread1 = Th ("T1")
3. Thread1.setdaemon (True)
4. #要在线程执行之前就设置这个量
5. Thread1.start ()
6. print "main thread is over"

Error: Exception in thread T1 (most likely raised during interpreter shutdown):

That is, the main thread does not wait for the child threads to end.

Multiple Child threads

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1. if __name__ = = ' __main__ ':
2. For I in range (3):
3. t = Th (str (i))
4. T.start ()
5. print "main thread is over"

Here t can handle multiple threads at the same time, i.e. T is the thread handle, and re-assignment does not affect the thread.

It is strange here that when you run T.run (), no more threads are executed. Although it is unclear, use Start (). It is understood that start () is non-blocking parallel, while run is blocked.

Thread Lock

The threading provides the thread lock, which enables threading synchronization.

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2. Import threading
4. Import time
10. Class Th (threading. Thread):
12. def __init__ (self, thread_name):
14. Threading. Thread.__init__ (self)
16. self.setname (thread_name)
20. def run (self):
22. Threadlock.acquire ()
24. #获得锁之后再运行
26. Print "This is thread" + self.getname ()
28. For I in range (3):
30. Time.sleep (1)
32. Print str (i)
34. print self.getname () + " is Over"
36. Threadlock.release ()
38. #释放锁
44. if __name__ = = ' __main__ ':
46. Threadlock = Threading. Lock ()
48. #设置全局锁
50. Thread1 = Th (' thread_1 ')
52. Thread2 = Th (' thread_2 ')
54. Thread1.start ()
56. Thread2.start ()

Get results:

This is thread thread_1

0

1

2

Thread_1 is Over

This is thread thread_2

0

1

2

Thread_2 is Over

[Python] Getting started with multithreading