code: def _fetch_router_chunk_data(self, router_ids=None):
  
          
  
          curr_router = []
          if len(router_ids) > self.sync_routers_chunk_size:
              # fetch routers by chunks to reduce the load on server and
              # to start router processing earlier
              for i in range(0, len(router_ids),
                             self.sync_routers_chunk_size):
                  routers = self.plugin_rpc.get_routers(
                                  self.context, (router_ids[i:i +
                                                 self.sync_routers_chunk_size]))
                  LOG.debug('Processing :%r', routers)
                  for r in routers:
                      curr_router.append(r)
          else:
              curr_router = self.plugin_rpc.get_routers(
                  self.context, router_ids=router_ids)
          return curr_router
docs: Fetch router data from the routing plugin in chunks.
  
                  :param router_ids: List of router_ids of routers to fetch
                  :return: List of router dicts of format:
                           [ {router_dict1}, {router_dict2},.....]