cadonna commented on a change in pull request #10851: URL: https://github.com/apache/kafka/pull/10851#discussion_r695633134
########## 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); Review comment: ```suggestion final Map<TaskId, Integer> tasksToRemainingStandbys = computeTasksToRemainingStandbys( numStandbyReplicas, statefulTasksWithClients ); ``` ########## 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)); Review comment: ```suggestion statefulTasksWithClients.forEach((taskId, clientId) -> assignStandbyTasksForActiveTask( numStandbyReplicas, taskId, clientId, rackAwareAssignmentTags, clients, tasksToRemainingStandbys )); ``` ########## 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) { Review comment: Yes, I think that makes sense. In this way you can also directly test the method. BTW, you can simply pass `statefulTaskIds` to this method instead of `statefulTasksWithClients`. The keys in `statefulTasksWithClients` should be the task IDs in `statefulTaskIds` and the values in `statefulTasksWithClients` are never used. ########## 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; + }); + + clientsPerTagValue.compute(tagValue, (key, currentValue) -> { + final Set<UUID> clientIdsForTagValue = Optional.ofNullable(currentValue).orElse(new HashSet<>()); + clientIdsForTagValue.add(clientId); + return clientIdsForTagValue; + }); Review comment: Isn't this the same as: ``` clientsPerTagValue.computeIfAbsent(tagValue, (ignored) -> new HashSet<>()).add(clientId); ``` ########## 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; + }); + + clientsPerTagValue.compute(tagValue, (key, currentValue) -> { + final Set<UUID> clientIdsForTagValue = Optional.ofNullable(currentValue).orElse(new HashSet<>()); + clientIdsForTagValue.add(clientId); + return clientIdsForTagValue; + }); + }); + } + } + + private static void assignStandbyTasksForActiveTask(final int numStandbyReplicas, + final TaskId activeTaskId, + final UUID activeTaskClient, + final Set<String> rackAwareAssignmentTags, + final Map<UUID, ClientState> clientStates, + final Map<TaskId, Integer> tasksToRemainingStandbys) { + final Map<String, Set<String>> tagKeyToTagValuesMapping = new HashMap<>(); + final Map<String, Set<UUID>> clientsPerTagValue = new HashMap<>(); + + fillClientsTagStatistics(clientStates, clientsPerTagValue, tagKeyToTagValuesMapping); Review comment: Why is the map from tag key to tag values computed for each active task? The should not change during the assignment and we can just compute it once in `assign()`. Do you agree? ########## 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; + }); + + clientsPerTagValue.compute(tagValue, (key, currentValue) -> { + final Set<UUID> clientIdsForTagValue = Optional.ofNullable(currentValue).orElse(new HashSet<>()); + clientIdsForTagValue.add(clientId); + return clientIdsForTagValue; + }); + }); + } + } + + private static void assignStandbyTasksForActiveTask(final int numStandbyReplicas, + final TaskId activeTaskId, + final UUID activeTaskClient, + final Set<String> rackAwareAssignmentTags, + final Map<UUID, ClientState> clientStates, + final Map<TaskId, Integer> tasksToRemainingStandbys) { + final Map<String, Set<String>> tagKeyToTagValuesMapping = new HashMap<>(); + final Map<String, Set<UUID>> clientsPerTagValue = new HashMap<>(); + + fillClientsTagStatistics(clientStates, clientsPerTagValue, tagKeyToTagValuesMapping); + + final ConstrainedPrioritySet standbyTaskClientsByTaskLoad = new ConstrainedPrioritySet( + (client, t) -> !clientStates.get(client).hasAssignedTask(t), + client -> clientStates.get(client).assignedTaskLoad() + ); + + final Set<UUID> usedClients = new HashSet<>(); + + standbyTaskClientsByTaskLoad.offerAll(clientStates.keySet()); + + int numRemainingStandbys = tasksToRemainingStandbys.get(activeTaskId); + + usedClients.add(activeTaskClient); + + while (numRemainingStandbys > 0) { + final Set<UUID> clientsOnAlreadyUsedTagDimensions = findClientsOnUsedTagDimensions(usedClients, + rackAwareAssignmentTags, + clientStates, + clientsPerTagValue, + tagKeyToTagValuesMapping); Review comment: ```suggestion final Set<UUID> clientsOnAlreadyUsedTagDimensions = findClientsOnUsedTagDimensions( usedClients, rackAwareAssignmentTags, clientStates, clientsPerTagValue, tagKeyToTagValuesMapping ); ``` ########## 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: Isn't this the same as: ``` tagKeyToTagValuesMapping.computeIfAbsent(tagKey, (ignored) -> new HashSet<>()).add(tagValue); ``` ########## 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) { Review comment: IMO, the code is easier readable if you name the variables consistently like `tagValueToClients` and `tagKeyToTagValues` or `clientsForTagValue` and `tagValuesForTagKey`. I prefer the former because it better visualises the mapping, but that is a matter of taste, I guess. -- 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
