使用 Python 进行线程编程

1）使用 Python 进行线程编程, 研究了如何同时使用线程和队列在 Python 中完成线程编程。

2） Queue — A synchronized queue class

The Queue module implements multi-producer, multi-consumer queues. It is especially useful in threaded programming when information must be exchanged safely between multiple threads. The Queue class in this module implements all the required locking semantics.

3） Queue – A thread-safe FIFO implementation，“It can be used to pass messages or other data between producer and consumer threads safely. Locking is handled for the caller, so it is simple to have as many threads as you want working with the same Queue instance.”
 

所以Queue对于调用者来说是线程安全的，可以放心的调用，下面给出一个例子。

 

          #!/usr/bin/env python
          import Queue
          import threading
          import urllib2
          import time
          
          hosts = ["http://yahoo.com", "http://google.com", "http://amazon.com",
          "http://ibm.com", "http://apple.com"]
          
          queue = Queue.Queue()
          
          class ThreadUrl(threading.Thread):
          """Threaded Url Grab"""
            def __init__(self, queue):
              threading.Thread.__init__(self)
              self.queue = queue
          
            def run(self):
              while True:
                #grabs host from queue
                host = self.queue.get()
            
                #grabs urls of hosts and prints first 1024 bytes of page
                url = urllib2.urlopen(host)
                print url.read(1024)
            
                #signals to queue job is done
                self.queue.task_done()
          
          start = time.time()
          def main():
          
            #spawn a pool of threads, and pass them queue instance 
            for i in range(5):
              t = ThreadUrl(queue)
              t.setDaemon(True)
              t.start()
              
           #populate queue with data   
              for host in hosts:
                queue.put(host)
           
           #wait on the queue until everything has been processed     
           queue.join()
          
          main()
          print "Elapsed Time: %s" % (time.time() - start)