Python中定义和调用线程 在Python中通过threading模块定义和调用线程的方法
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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
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