Python重新加载模块的实现方法

# 在主进程中启动多进程
def begin():
  """ 启动多进程 """
  plist = []
  for i in xrange(Num_process):
    p = Process(target=pre_run)
    p.start()
    plist.append(p)
  # 此进程监听redis消息，收到消息，即执行reload方法
  p = Process(target=reload_spider)
  p.start()
  plist.append(p)
  for p in plist:
    p.join()

# 监听redis，执行reload方法
def reload_spider():
  """ 监听文件变化，自动reload """
  rconn = redis.Redis(host=settings.REDIS_HOST, port=settings.REDIS_PORT, db=settings.REDIS_DB, password=settings.REDIS_PW)
  while True:
    try:
      key = 'reload-spider'
      value = rconn.get(key)
      print value
      if value == '1':
        crawler_module = importlib.import_module('crawlers.%s' % 'temp'.lower())
        reload(crawler_module)
        crawlerClass = getattr(crawler_module, 'temp'.upper())
        print 'reload_spider 中的class： %s' % (crawlerClass.name)
      # rconn.delete(key)
    except Exception, e:
      pass
    time.sleep(3)

crawler = get_crawler_from_factory(mq_service, message)
  print crawler.name

def pre_run():
  t = threading.Thread(target=reload_spider, name='LoopThread')
  t.start()
  # t.join()
 
  """ 在每个进程里面再使用多线程 """
  pool = ThreadPool(Num_Thread)
  # 初始化mq通道
  mq_service = RabbitMqService()
 
  def callback(ch, method, properties, body):
    # 消息确认
    mq_service.input_channel.basic_ack(delivery_tag=method.delivery_tag)
    # 获取当前线程的名字
    current_process_name = multiprocessing.current_process().name
    logger.debug('当前进程名称：%s - pid: %s' % (current_process_name, os.getpid()))
    logger.debug('进程 %s，收到消息： %s' % (current_process_name, body))
    # 收到任务消息，丢给线程池处理
    pool.apply_async(run, (properties, body, mq_service))
  # 开始监听入口通道
  mq_service.receive(callback)

def reload_spider():
  """ 监听文件变化，自动reload """
  rconn = redis.Redis(host=settings.REDIS_HOST, port=settings.REDIS_PORT, db=settings.REDIS_DB, password=settings.REDIS_PW)
  while True:
    try:
      key = 'reload-spider'
      value = rconn.get(key)
      print value
      if value == '1':
        crawler_module = importlib.import_module('crawlers.%s' % 'temp'.lower())
        reload(crawler_module)
        crawlerClass = getattr(crawler_module, 'temp'.upper())
        print 'reload_spider 中的class： %s' % (crawlerClass.name)
      # rconn.delete(key)
    except Exception, e:
      pass
    time.sleep(3)