在Python中通过threading模块定义和调用线程的方法

定义线程

最简单的方法：使用target指定线程要执行的目标函数，再使用start()启动。

语法：

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

group恒为None，保留未来使用。target为要执行的函数名。name为线程名，默认为Thread-N，通常使用默认即可。但服务器端程序线程功能不同时，建议命名。

#!/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()

执行结果：

$ ./threading_define.py

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

确定当前线程

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

import threading
import time

def first_function():
 print (threading.currentThread().getName()+ str(' is Starting \n'))
 time.sleep(3)
 print (threading.currentThread().getName()+ str( ' is Exiting \n'))

def second_function():
 print (threading.currentThread().getName()+ str(' is Starting \n'))
 time.sleep(2)
 print (threading.currentThread().getName()+ str( ' is Exiting \n'))

def third_function():
 print (threading.currentThread().getName()+\
 str(' is Starting \n'))
 time.sleep(1)
 print (threading.currentThread().getName()+ str( ' is Exiting \n'))

if __name__ == "__main__":
 t1 = threading.Thread(name='first_function', target=first_function)
 t2 = threading.Thread(name='second_function', target=second_function)
 t3 = threading.Thread(name='third_function',target=third_function)
 t1.start()
 t2.start()
 t3.start()

执行结果：

$ ./threading_name.py

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

配合logging模块一起使用：

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

import logging
import threading
import time

logging.basicConfig(
 level=logging.DEBUG,
 format='[％(levelname)s] (％(threadName)-10s) ％(message)s',
 )

def worker():
 logging.debug('Starting')
 time.sleep(2)
 logging.debug('Exiting')

def my_service():
 logging.debug('Starting')
 time.sleep(3)
 logging.debug('Exiting')

t = threading.Thread(name='my_service', target=my_service)
w = threading.Thread(name='worker', target=worker)
w2 = threading.Thread(target=worker) # use default name
w.start()
w2.start()
t.start()

执行结果：

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

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

在子类中使用线程

前面我们的线程都是结构化编程的形式来创建。通过集成threading.Thread类也可以创建线程。Thread类首先完成一些基本上初始化，然后调用它的run()。run()方法会会调用传递给构造函数的目标函数。

#!/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")

执行结果：

$ ./threading_subclass.py

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