lkokhreidze commented on a change in pull request #10851: URL: https://github.com/apache/kafka/pull/10851#discussion_r695736026
########## File path: streams/src/main/java/org/apache/kafka/streams/processor/internals/assignment/ClientTagAwareStandbyTaskAssignor.java ########## @@ -0,0 +1,208 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.kafka.streams.processor.internals.assignment; + +import org.apache.kafka.streams.processor.TaskId; +import org.apache.kafka.streams.processor.internals.assignment.AssignorConfiguration.AssignmentConfigs; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.HashMap; +import java.util.HashSet; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Optional; +import java.util.Set; +import java.util.UUID; +import java.util.function.Function; + +import static java.util.stream.Collectors.toMap; + +/** + * Distributes standby tasks over different tag dimensions. + * Only tags specified via {@link AssignmentConfigs#rackAwareAssignmentTags} are taken into account. + * Standby task distribution is on a best-effort basis. For example, if there are not enough clients available + * on different tag dimensions compared to an active and corresponding standby task, + * in that case, the algorithm will fall back to distributing tasks on least-loaded clients. + */ +class ClientTagAwareStandbyTaskAssignor implements StandbyTaskAssignor { + private static final Logger log = LoggerFactory.getLogger(ClientTagAwareStandbyTaskAssignor.class); + + @Override + public boolean assign(final Map<UUID, ClientState> clients, + final Set<TaskId> allTaskIds, + final Set<TaskId> statefulTaskIds, + final AssignorConfiguration.AssignmentConfigs configs) { + final int numStandbyReplicas = configs.numStandbyReplicas; + final Set<String> rackAwareAssignmentTags = new HashSet<>(configs.rackAwareAssignmentTags); + final Map<TaskId, UUID> statefulTasksWithClients = new HashMap<>(); + + statefulTaskIds.forEach(statefulTaskId -> clients.forEach((uuid, clientState) -> { + if (clientState.activeTasks().contains(statefulTaskId)) { + statefulTasksWithClients.put(statefulTaskId, uuid); + } + })); + + final Map<TaskId, Integer> tasksToRemainingStandbys = computeTasksToRemainingStandbys(numStandbyReplicas, + statefulTasksWithClients); + + statefulTasksWithClients.forEach((taskId, clientId) -> assignStandbyTasksForActiveTask(numStandbyReplicas, + taskId, + clientId, + rackAwareAssignmentTags, + clients, + tasksToRemainingStandbys)); + + return true; + } + + @Override + public boolean isAllowedTaskMovement(final ClientState source, final ClientState destination) { + final Map<String, String> sourceClientTags = source.clientTags(); + final Map<String, String> destinationClientTags = destination.clientTags(); + + for (final Entry<String, String> sourceClientTagEntry : sourceClientTags.entrySet()) { + if (!sourceClientTagEntry.getValue().equals(destinationClientTags.get(sourceClientTagEntry.getKey()))) { + return false; + } + } + + return true; + } + + private static Map<TaskId, Integer> computeTasksToRemainingStandbys(final int numStandbyReplicas, final Map<TaskId, UUID> statefulTasksWithClients) { + return statefulTasksWithClients.keySet().stream().collect(toMap(Function.identity(), t -> numStandbyReplicas)); + } + + private static void fillClientsTagStatistics(final Map<UUID, ClientState> clientStates, + final Map<String, Set<UUID>> clientsPerTagValue, + final Map<String, Set<String>> tagKeyToTagValuesMapping) { + for (final Entry<UUID, ClientState> clientStateEntry : clientStates.entrySet()) { + final UUID clientId = clientStateEntry.getKey(); + final ClientState clientState = clientStateEntry.getValue(); + + clientState.clientTags().forEach((tagKey, tagValue) -> { + tagKeyToTagValuesMapping.compute(tagKey, (key, currentValue) -> { + final Set<String> tagValuesForKey = Optional.ofNullable(currentValue).orElse(new HashSet<>()); + tagValuesForKey.add(tagValue); + return tagValuesForKey; + }); Review comment: Fixed -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
