# -*- coding:utf-8 -*-#! python2import subprocessfrom Queue import Queueimport threadingclass Pinger(object):  def __init__(self, ip_list, thread_num=2):    self._ip_list = ip_list    self._thread_num = thread_num    self._queue = Queue(len(ip_list))  def ping(self, thread_id):    while True:      if self._queue.empty():        break      addr = self._queue.get()      print 'Thread %s: Ping %s' % (thread_id, addr)      ret = subprocess.call('ping -c 1 %s' % (addr),                 shell=True,                 stdout=open("/dev/null", 'w'),                 stderr=subprocess.STDOUT)      if ret == 0:        print '%s: is still alive' % addr      else:        print '%s: did not respond ' % addr      self._queue.task_done() #unfinished tasks -= 1  def run(self):    for ip in self._ip_list:      self._queue.put(ip) #unfinished_tasks += 1    print '---------------------task begin------------------'    for i in range(self._thread_num):      thrd = threading.Thread(target=self.ping, args=(i + 1,))      #thrd.setDaemon(True)      thrd.start()    self._queue.join() # 主線程一直阻塞，一直等到Queue.unfiinshed_tasks == 0    print '---------------------task done-------------------'