python多线程编程

python提供多线程编程模块有三个：thread、threading、Queen，主要使用threading模块
主要原因是因为：首先threading模块比thread模块更先进，对线程支持更为完善。其次，thread模块同步语言很少，而threading模块则很多。

1、thread模块

start_new_thread()函数是thread 模块的一个关键函数，它的语法与内建的apply()函数完全
一样，其参数为：函数，函数的参数以及可选的关键字参数。不同的是，函数不是在主线程里运行，而是产生一个新的线程来运行这个函数。
start_new_thread()要求一定要有前两个参数。所以，就算我们想要运行的函数不要参数，我们也要传一个空的元组。

import thread
 from time import ctime,sleep
 loops[4,2]
 def loop(nloop,nsec,lock):
 print 'start loop', nloop 'at',ctime()
 sleep(nsec)
 print 'loop',nloop 'done at',ctime()
 lock.release() #释放线程锁
 
 
def mian():
 print 'starting at',ctime()
 nloops=range(len(loops))
 locks=[]
 
 
  for i in nloops:
        lock=thread.allocate_lock()   #产生一个线程锁
        lock.acquire()                        #获得线程锁的实例
        locks.append(lock)

  for i in nloops:
        thread.start_new_thread(loop,(i,loops[i],locks[i])  #开启线程  

  for i in nloops :
        while locks[i].locked():pass
 
 
if __name__== '__main__':
 main()

2、threding模块

from time import ctime ,sleep
 import thread,threading
 loops=[4,2]
 
 
class Mythread(threading.Thread):
 
 
 def __init__(self,func,args,name):        
       threading.Thread.__init__(self)        
       self.func=func        
       self.args=args        
       self.name=name

 def run(self):        
       apply(self.func,self.args)
 
 
def loop(nloop,nsec):
 print 'start loop',nloop,' at:',ctime()
 sleep(nsec)
 print 'loop',nloop,' done at',ctime()
 
 
def main():
 print 'start at',ctime()
 threads=[]
 nloops=range(len(loops))
 for i in nloops:
 t=Mythread(loop,(i,loops[i]),loop.name)
 threads.append(t)
 for i in nloops:
 threads[i].start()
 for i in nloops:
 threads[i].join()
 print 'all done at',ctime()
 
 
if __name__ == '__main__':
 main()

3、Queue模块可以实现线程同步先进先出

 from Queue import Queue
 import threading
 from time import sleep
 from random import randint
 
 
def writeQ(queue):
 print 'prducing object for Q...'
 queue.put('xxx',1)
 print 'Size now...',queue.qsize()
 
 
def readQ(queue):
 val=queue.get(1)
 print 'consumed object from Q... size Now',queue.qsize()
 
 
def writer(queue,loops):
 for i in loops:
 writeQ(queue)
 sleep(4)
 
 
def reader(queue,loops):
 for i in loops:
 readQ(queue)
 sleep(2)
 
 
funcs=[writer,reader]
 nloops=range(len(funcs))
 
 
def main():
 threads=[]
 queue= Queue(32)
 loops=range(randint(2,5))
 for i in nloops:
 t=threading.Thread(target=funcs[i],args=(queue,loops))
 threads.append(t)
 for i in nloops:
 threads[i].start()
 for i in nloops:
 threads[i].join()
 print 'all done'
 
 
if __name__ == '__main__':
 main()