cadonna commented on code in PR #18652: URL: https://github.com/apache/kafka/pull/18652#discussion_r1930444373
########## group-coordinator/src/main/java/org/apache/kafka/coordinator/group/streams/assignor/StickyTaskAssignor.java: ########## @@ -0,0 +1,401 @@ +/* + * 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.coordinator.group.streams.assignor; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.Comparator; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Iterator; +import java.util.Map; +import java.util.Objects; +import java.util.Optional; +import java.util.Set; +import java.util.stream.Collectors; + +public class StickyTaskAssignor implements TaskAssignor { + + public static final String STICKY_ASSIGNOR_NAME = "sticky"; + private static final Logger log = LoggerFactory.getLogger(StickyTaskAssignor.class); + // helper data structures: + private TaskPairs taskPairs; + Map<TaskId, Member> activeTaskToPrevMember; + Map<TaskId, Set<Member>> standbyTaskToPrevMember; + Map<String, ProcessState> processIdToState; + int allTasks; + int totalCapacity; + int tasksPerMember; + + @Override + public String name() { + return STICKY_ASSIGNOR_NAME; + } + + @Override + public GroupAssignment assign(final GroupSpec groupSpec, final TopologyDescriber topologyDescriber) throws TaskAssignorException { + initialize(groupSpec, topologyDescriber); + //active + Set<TaskId> activeTasks = toTaskIds(groupSpec, topologyDescriber, true); + assignActive(activeTasks); + //standby + final int numStandbyReplicas = + groupSpec.assignmentConfigs().isEmpty() ? 0 + : Integer.parseInt(groupSpec.assignmentConfigs().get("numStandbyReplicas")); + if (numStandbyReplicas > 0) { + Set<TaskId> statefulTasks = toTaskIds(groupSpec, topologyDescriber, false); + assignStandby(statefulTasks, numStandbyReplicas); + } + return buildGroupAssignment(groupSpec.members().keySet()); + } + + private Set<TaskId> toTaskIds(final GroupSpec groupSpec, final TopologyDescriber topologyDescriber, final boolean isActive) { + Set<TaskId> ret = new HashSet<>(); + for (String subtopology : groupSpec.subtopologies()) { + if (isActive || topologyDescriber.isStateful(subtopology)) { + int numberOfPartitions = topologyDescriber.numTasks(subtopology); + for (int i = 0; i < numberOfPartitions; i++) { + ret.add(new TaskId(subtopology, i)); + } + } + } + return ret; + } + + private void initialize(final GroupSpec groupSpec, final TopologyDescriber topologyDescriber) { + allTasks = 0; + for (String subtopology : groupSpec.subtopologies()) { + int numberOfPartitions = topologyDescriber.numTasks(subtopology); + allTasks += numberOfPartitions; + } + totalCapacity = groupSpec.members().size(); + tasksPerMember = computeTasksPerMember(allTasks, totalCapacity); + taskPairs = new TaskPairs(allTasks * (allTasks - 1) / 2); + processIdToState = new HashMap<>(); + activeTaskToPrevMember = new HashMap<>(); + standbyTaskToPrevMember = new HashMap<>(); + for (Map.Entry<String, AssignmentMemberSpec> memberEntry : groupSpec.members().entrySet()) { + final String memberId = memberEntry.getKey(); + final String processId = memberEntry.getValue().processId(); + final Member member = new Member(processId, memberId); + final AssignmentMemberSpec memberSpec = memberEntry.getValue(); + processIdToState.putIfAbsent(processId, new ProcessState(processId)); + processIdToState.get(processId).addMember(memberId); + // prev active tasks + for (Map.Entry<String, Set<Integer>> entry : memberSpec.activeTasks().entrySet()) { Review Comment: As far as I understand, the assignor always receives the latest members as inputs. If a member is fenced before this specific heartbeat, then the assignor will know that because it replayed the consumer offset topic up until the end. All operations on a specific group (also fencing) are executed sequentially in an event loop and with the most up-to-date data from the consumer offset topic. So if a member is fenced the next operations see that immediately. Regarding integration tests, it does not seem we have many integration tests for the client-side `StickyTaskAssignor` which is not good. Currently, we cannot write integration tests because we are still missing some parts like the `GroupMetaManager`, but we definitely need to write them. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
