筛选计算主机，按权重选择并申请资源

712    def _get_sorted_hosts(self, spec_obj, host_states, index):713        """Returns a list of HostState objects that match the required714        scheduling constraints for the request spec object and have been sorted715        according to the weighers.716        """717        filtered_hosts = self.host_manager.get_filtered_hosts(host_states,718            spec_obj, index)719720        LOG.debug("Filtered %(hosts)s", {'hosts': filtered_hosts})721722        if not filtered_hosts:723            return []724725        weighed_hosts = self.host_manager.get_weighed_hosts(726            filtered_hosts, spec_obj)

43    if maxval is None:44        maxval = max(weight_list)4546    if minval is None:47        minval = min(weight_list)4849    maxval = float(maxval)50    minval = float(minval)5152    if minval == maxval:53        return [0] * len(weight_list)5455    range_ = maxval - minval56    return ((i - minval) / range_ for i in weight_list)

155            log_data = {}156157            for i, weight in enumerate(weights):158                obj = weighed_objs[i]159                multiplier = weigher.weight_multiplier(obj.obj)160                weigher_score = multiplier * weight161                obj.weight += weigher_score162163                log_data[(obj.obj.host, obj.obj.nodename)] = (164                    f"{multiplier} * {weight}")165166            LOG.debug(167                "%s: score (multiplier * weight) %s",168                weigher.__class__.__name__,169                {name: log for name, log in log_data.items()}170            )171172        return sorted(weighed_objs, key=lambda x: x.weight, reverse=True)

746        # We randomize the first element in the returned list to alleviate747        # congestion where the same host is consistently selected among748        # numerous potential hosts for similar request specs.749        host_subset_size = CONF.filter_scheduler.host_subset_size750        if host_subset_size < len(weighed_hosts):751            weighed_subset = weighed_hosts[0:host_subset_size]752        else:753            weighed_subset = weighed_hosts754755        chosen_host = random.choice(weighed_subset)756        weighed_hosts.remove(chosen_host)757        return [chosen_host] + weighed_hosts

455                # TODO(jaypipes): Loop through all allocation_requests instead456                # of just trying the first one. For now, since we'll likely457                # want to order the allocation_requests in the future based on458                # information in the provider summaries, we'll just try to459                # claim resources using the first allocation_request460                alloc_req = host.allocation_candidates[0]461                if utils.claim_resources(462                    elevated, self.placement_client, spec_obj, instance_uuid,463                    alloc_req,464                    allocation_request_version=allocation_request_version,465                ):466                    claimed_host = host467                    break468469            if claimed_host is None:470                # We weren't able to claim resources in the placement API471                # for any of the sorted hosts identified. So, clean up any472                # successfully-claimed resources for prior instances in473                # this request and return an empty list which will cause474                # select_destinations() to raise NoValidHost475                LOG.debug("Unable to successfully claim against any host.")476                break

478            claimed_instance_uuids.append(instance_uuid)479            claimed_hosts.append(claimed_host)480            claimed_alloc_reqs.append(alloc_req)481482            # update the provider mapping in the request spec based483            # on the allocated candidate as the _consume_selected_host depends484            # on this information to temporally consume PCI devices tracked in485            # placement486            for request_group in spec_obj.requested_resources:487                request_group.provider_uuids = alloc_req[488                    'mappings'][request_group.requester_id]489490            # Now consume the resources so the filter/weights will change for491            # the next instance.492            self._consume_selected_host(493                claimed_host, spec_obj, instance_uuid=instance_uuid)494495        # Check if we were able to fulfill the request. If not, this call will496        # raise a NoValidHost exception.497        self._ensure_sufficient_hosts(498            context, claimed_hosts, num_instances, claimed_instance_uuids)