Define and call threads through the threading module in Python-Python Tutorial-php.cn

Define and call threads through the threading module in Python

高洛峰

Release： 2017-02-28 17:22:31

Original

1397 people have browsed it

Define thread

The simplest method: use target to specify the target function to be executed by the thread, and then use start() to start.

Syntax:

class threading.Thread(group=None, target=None, name=None, args=(), kwargs={})

Copy after login

group is always None and is reserved for future use. target is the name of the function to be executed. name is the thread name, the default is Thread-N, usually the default can be used. However, when the server-side program thread functions are different, it is recommended to name them.

#!/usr/bin/env python3
# coding=utf-8
import threading

def function(i):
  print ("function called by thread {0}".format(i))
threads = []

for i in range(5):
  t = threading.Thread(target=function , args=(i,))
  threads.append(t)
  t.start()
  t.join()

Copy after login

Execution result:

$ ./threading_define.py

Copy after login

function called by thread 0
function called by thread 1
function called by thread 2
function called by thread 3
function called by thread 4

Copy after login

Determine the current thread

#!/usr/bin/env python3
# coding=utf-8

import threading
import time

def first_function():
  print (threading.currentThread().getName()+ str(&#39; is Starting \n&#39;))
  time.sleep(3)
  print (threading.currentThread().getName()+ str( &#39; is Exiting \n&#39;))
  
def second_function():
  print (threading.currentThread().getName()+ str(&#39; is Starting \n&#39;))
  time.sleep(2)
  print (threading.currentThread().getName()+ str( &#39; is Exiting \n&#39;))
  
def third_function():
  print (threading.currentThread().getName()+\
  str(&#39; is Starting \n&#39;))
  time.sleep(1)
  print (threading.currentThread().getName()+ str( &#39; is Exiting \n&#39;))
  
if __name__ == "__main__":
  t1 = threading.Thread(name=&#39;first_function&#39;, target=first_function)
  t2 = threading.Thread(name=&#39;second_function&#39;, target=second_function)
  t3 = threading.Thread(name=&#39;third_function&#39;,target=third_function)
  t1.start()
  t2.start()
  t3.start()

Copy after login

Execution result:

$ ./threading_name.py

Copy after login

first_function is Starting 
second_function is Starting 
third_function is Starting 
third_function is Exiting 
second_function is Exiting 
first_function is Exiting

Copy after login

Use with logging module:

#!/usr/bin/env python3
# coding=utf-8

import logging
import threading
import time

logging.basicConfig(
  level=logging.DEBUG,
  format=&#39;[%(levelname)s] (%(threadName)-10s) %(message)s&#39;,
  )
  
def worker():
  logging.debug(&#39;Starting&#39;)
  time.sleep(2)
  logging.debug(&#39;Exiting&#39;)
  
def my_service():
  logging.debug(&#39;Starting&#39;)
  time.sleep(3)
  logging.debug(&#39;Exiting&#39;)
  
t = threading.Thread(name=&#39;my_service&#39;, target=my_service)
w = threading.Thread(name=&#39;worker&#39;, target=worker)
w2 = threading.Thread(target=worker) # use default name
w.start()
w2.start()
t.start()

Copy after login

Execution result:

$ ./threading_names_log.py[DEBUG] (worker  ) Starting

Copy after login

[DEBUG] (Thread-1 ) Starting
[DEBUG] (my_service) Starting
[DEBUG] (worker  ) Exiting
[DEBUG] (Thread-1 ) Exiting
[DEBUG] (my_service) Exiting

Copy after login

Using threads in subclasses

In front of us Threads are created in the form of structured programming. Threads can also be created by integrating the threading.Thread class. The Thread class first completes some basic initialization and then calls its run(). The run() method will call the target function passed to the constructor.

#!/usr/bin/env python3
# coding=utf-8

import logging
import threading
import time

exitFlag = 0

class myThread (threading.Thread):
  def __init__(self, threadID, name, counter):
    threading.Thread.__init__(self)
    self.threadID = threadID
    self.name = name
    self.counter = counter
    
  def run(self):
    print ("Starting " + self.name)
    print_time(self.name, self.counter, 5)
    print ("Exiting " + self.name)
    
def print_time(threadName, delay, counter):
  while counter:
    if exitFlag:
      thread.exit()
    time.sleep(delay)
    print ("%s: %s" %(threadName, time.ctime(time.time())))
    counter -= 1
    
# Create new threads
thread1 = myThread(1, "Thread-1", 1)
thread2 = myThread(2, "Thread-2", 2)
# Start new Threads
thread1.start()
thread2.start()
print ("Exiting Main Thread")

Copy after login

Execution result:

$ ./threading_subclass.py

Copy after login

Starting Thread-1
Starting Thread-2
Exiting Main Thread
Thread-1: Tue Sep 15 11:03:21 2015
Thread-2: Tue Sep 15 11:03:22 2015
Thread-1: Tue Sep 15 11:03:22 2015
Thread-1: Tue Sep 15 11:03:23 2015
Thread-2: Tue Sep 15 11:03:24 2015
Thread-1: Tue Sep 15 11:03:24 2015
Thread-1: Tue Sep 15 11:03:25 2015
Exiting Thread-1
Thread-2: Tue Sep 15 11:03:26 2015
Thread-2: Tue Sep 15 11:03:28 2015
Thread-2: Tue Sep 15 11:03:30 2015
Exiting Thread-2

Copy after login

More For articles related to defining and calling threads through the threading module in Python, please pay attention to the PHP Chinese website!