Examples with StickyTaskAssignor org.apache.kafka.streams.processor.internals.assignment.StickyTaskAssignor used on opensource projects

Example 1 with StickyTaskAssignor

use of org.apache.kafka.streams.processor.internals.assignment.StickyTaskAssignor in project kafka by apache.

the class StreamPartitionAssignor method assign.

/*
     * This assigns tasks to consumer clients in the following steps.
     *
     * 0. check all repartition source topics and use internal topic manager to make sure
     *    they have been created with the right number of partitions.
     *
     * 1. using user customized partition grouper to generate tasks along with their
     *    assigned partitions; also make sure that the task's corresponding changelog topics
     *    have been created with the right number of partitions.
     *
     * 2. using TaskAssignor to assign tasks to consumer clients.
     *    - Assign a task to a client which was running it previously.
     *      If there is no such client, assign a task to a client which has its valid local state.
     *    - A client may have more than one stream threads.
     *      The assignor tries to assign tasks to a client proportionally to the number of threads.
     *    - We try not to assign the same set of tasks to two different clients
     *    We do the assignment in one-pass. The result may not satisfy above all.
     *
     * 3. within each client, tasks are assigned to consumer clients in round-robin manner.
     */
@Override
public Map<String, Assignment> assign(Cluster metadata, Map<String, Subscription> subscriptions) {
    // construct the client metadata from the decoded subscription info
    Map<UUID, ClientMetadata> clientsMetadata = new HashMap<>();
    for (Map.Entry<String, Subscription> entry : subscriptions.entrySet()) {
        String consumerId = entry.getKey();
        Subscription subscription = entry.getValue();
        SubscriptionInfo info = SubscriptionInfo.decode(subscription.userData());
        // create the new client metadata if necessary
        ClientMetadata clientMetadata = clientsMetadata.get(info.processId);
        if (clientMetadata == null) {
            clientMetadata = new ClientMetadata(info.userEndPoint);
            clientsMetadata.put(info.processId, clientMetadata);
        }
        // add the consumer to the client
        clientMetadata.addConsumer(consumerId, info);
    }
    log.info("stream-thread [{}] Constructed client metadata {} from the member subscriptions.", streamThread.getName(), clientsMetadata);
    // ---------------- Step Zero ---------------- //
    // parse the topology to determine the repartition source topics,
    // making sure they are created with the number of partitions as
    // the maximum of the depending sub-topologies source topics' number of partitions
    Map<Integer, TopologyBuilder.TopicsInfo> topicGroups = streamThread.builder.topicGroups();
    Map<String, InternalTopicMetadata> repartitionTopicMetadata = new HashMap<>();
    for (TopologyBuilder.TopicsInfo topicsInfo : topicGroups.values()) {
        for (InternalTopicConfig topic : topicsInfo.repartitionSourceTopics.values()) {
            repartitionTopicMetadata.put(topic.name(), new InternalTopicMetadata(topic));
        }
    }
    boolean numPartitionsNeeded;
    do {
        numPartitionsNeeded = false;
        for (TopologyBuilder.TopicsInfo topicsInfo : topicGroups.values()) {
            for (String topicName : topicsInfo.repartitionSourceTopics.keySet()) {
                int numPartitions = repartitionTopicMetadata.get(topicName).numPartitions;
                // try set the number of partitions for this repartition topic if it is not set yet
                if (numPartitions == UNKNOWN) {
                    for (TopologyBuilder.TopicsInfo otherTopicsInfo : topicGroups.values()) {
                        Set<String> otherSinkTopics = otherTopicsInfo.sinkTopics;
                        if (otherSinkTopics.contains(topicName)) {
                            // use the maximum of all its source topic partitions as the number of partitions
                            for (String sourceTopicName : otherTopicsInfo.sourceTopics) {
                                Integer numPartitionsCandidate;
                                // map().join().join(map())
                                if (repartitionTopicMetadata.containsKey(sourceTopicName)) {
                                    numPartitionsCandidate = repartitionTopicMetadata.get(sourceTopicName).numPartitions;
                                } else {
                                    numPartitionsCandidate = metadata.partitionCountForTopic(sourceTopicName);
                                    if (numPartitionsCandidate == null) {
                                        repartitionTopicMetadata.get(topicName).numPartitions = NOT_AVAILABLE;
                                    }
                                }
                                if (numPartitionsCandidate != null && numPartitionsCandidate > numPartitions) {
                                    numPartitions = numPartitionsCandidate;
                                }
                            }
                        }
                    }
                    // another iteration is needed
                    if (numPartitions == UNKNOWN)
                        numPartitionsNeeded = true;
                    else
                        repartitionTopicMetadata.get(topicName).numPartitions = numPartitions;
                }
            }
        }
    } while (numPartitionsNeeded);
    // augment the metadata with the newly computed number of partitions for all the
    // repartition source topics
    Map<TopicPartition, PartitionInfo> allRepartitionTopicPartitions = new HashMap<>();
    for (Map.Entry<String, InternalTopicMetadata> entry : repartitionTopicMetadata.entrySet()) {
        String topic = entry.getKey();
        Integer numPartitions = entry.getValue().numPartitions;
        for (int partition = 0; partition < numPartitions; partition++) {
            allRepartitionTopicPartitions.put(new TopicPartition(topic, partition), new PartitionInfo(topic, partition, null, new Node[0], new Node[0]));
        }
    }
    // ensure the co-partitioning topics within the group have the same number of partitions,
    // and enforce the number of partitions for those repartition topics to be the same if they
    // are co-partitioned as well.
    ensureCopartitioning(streamThread.builder.copartitionGroups(), repartitionTopicMetadata, metadata);
    // make sure the repartition source topics exist with the right number of partitions,
    // create these topics if necessary
    prepareTopic(repartitionTopicMetadata);
    metadataWithInternalTopics = metadata.withPartitions(allRepartitionTopicPartitions);
    log.debug("stream-thread [{}] Created repartition topics {} from the parsed topology.", streamThread.getName(), allRepartitionTopicPartitions.values());
    // ---------------- Step One ---------------- //
    // get the tasks as partition groups from the partition grouper
    Set<String> allSourceTopics = new HashSet<>();
    Map<Integer, Set<String>> sourceTopicsByGroup = new HashMap<>();
    for (Map.Entry<Integer, TopologyBuilder.TopicsInfo> entry : topicGroups.entrySet()) {
        allSourceTopics.addAll(entry.getValue().sourceTopics);
        sourceTopicsByGroup.put(entry.getKey(), entry.getValue().sourceTopics);
    }
    Map<TaskId, Set<TopicPartition>> partitionsForTask = streamThread.partitionGrouper.partitionGroups(sourceTopicsByGroup, metadataWithInternalTopics);
    // check if all partitions are assigned, and there are no duplicates of partitions in multiple tasks
    Set<TopicPartition> allAssignedPartitions = new HashSet<>();
    Map<Integer, Set<TaskId>> tasksByTopicGroup = new HashMap<>();
    for (Map.Entry<TaskId, Set<TopicPartition>> entry : partitionsForTask.entrySet()) {
        Set<TopicPartition> partitions = entry.getValue();
        for (TopicPartition partition : partitions) {
            if (allAssignedPartitions.contains(partition)) {
                log.warn("stream-thread [{}] Partition {} is assigned to more than one tasks: {}", streamThread.getName(), partition, partitionsForTask);
            }
        }
        allAssignedPartitions.addAll(partitions);
        TaskId id = entry.getKey();
        Set<TaskId> ids = tasksByTopicGroup.get(id.topicGroupId);
        if (ids == null) {
            ids = new HashSet<>();
            tasksByTopicGroup.put(id.topicGroupId, ids);
        }
        ids.add(id);
    }
    for (String topic : allSourceTopics) {
        List<PartitionInfo> partitionInfoList = metadataWithInternalTopics.partitionsForTopic(topic);
        if (!partitionInfoList.isEmpty()) {
            for (PartitionInfo partitionInfo : partitionInfoList) {
                TopicPartition partition = new TopicPartition(partitionInfo.topic(), partitionInfo.partition());
                if (!allAssignedPartitions.contains(partition)) {
                    log.warn("stream-thread [{}] Partition {} is not assigned to any tasks: {}", streamThread.getName(), partition, partitionsForTask);
                }
            }
        } else {
            log.warn("stream-thread [{}] No partitions found for topic {}", streamThread.getName(), topic);
        }
    }
    // add tasks to state change log topic subscribers
    Map<String, InternalTopicMetadata> changelogTopicMetadata = new HashMap<>();
    for (Map.Entry<Integer, TopologyBuilder.TopicsInfo> entry : topicGroups.entrySet()) {
        final int topicGroupId = entry.getKey();
        final Map<String, InternalTopicConfig> stateChangelogTopics = entry.getValue().stateChangelogTopics;
        for (InternalTopicConfig topicConfig : stateChangelogTopics.values()) {
            // the expected number of partitions is the max value of TaskId.partition + 1
            int numPartitions = UNKNOWN;
            if (tasksByTopicGroup.get(topicGroupId) != null) {
                for (TaskId task : tasksByTopicGroup.get(topicGroupId)) {
                    if (numPartitions < task.partition + 1)
                        numPartitions = task.partition + 1;
                }
                InternalTopicMetadata topicMetadata = new InternalTopicMetadata(topicConfig);
                topicMetadata.numPartitions = numPartitions;
                changelogTopicMetadata.put(topicConfig.name(), topicMetadata);
            } else {
                log.debug("stream-thread [{}] No tasks found for topic group {}", streamThread.getName(), topicGroupId);
            }
        }
    }
    prepareTopic(changelogTopicMetadata);
    log.debug("stream-thread [{}] Created state changelog topics {} from the parsed topology.", streamThread.getName(), changelogTopicMetadata);
    // ---------------- Step Two ---------------- //
    // assign tasks to clients
    Map<UUID, ClientState> states = new HashMap<>();
    for (Map.Entry<UUID, ClientMetadata> entry : clientsMetadata.entrySet()) {
        states.put(entry.getKey(), entry.getValue().state);
    }
    log.debug("stream-thread [{}] Assigning tasks {} to clients {} with number of replicas {}", streamThread.getName(), partitionsForTask.keySet(), states, numStandbyReplicas);
    final StickyTaskAssignor<UUID> taskAssignor = new StickyTaskAssignor<>(states, partitionsForTask.keySet());
    taskAssignor.assign(numStandbyReplicas);
    log.info("stream-thread [{}] Assigned tasks to clients as {}.", streamThread.getName(), states);
    // ---------------- Step Three ---------------- //
    // construct the global partition assignment per host map
    partitionsByHostState = new HashMap<>();
    for (Map.Entry<UUID, ClientMetadata> entry : clientsMetadata.entrySet()) {
        HostInfo hostInfo = entry.getValue().hostInfo;
        if (hostInfo != null) {
            final Set<TopicPartition> topicPartitions = new HashSet<>();
            final ClientState state = entry.getValue().state;
            for (final TaskId id : state.activeTasks()) {
                topicPartitions.addAll(partitionsForTask.get(id));
            }
            partitionsByHostState.put(hostInfo, topicPartitions);
        }
    }
    // within the client, distribute tasks to its owned consumers
    Map<String, Assignment> assignment = new HashMap<>();
    for (Map.Entry<UUID, ClientMetadata> entry : clientsMetadata.entrySet()) {
        final Set<String> consumers = entry.getValue().consumers;
        final ClientState state = entry.getValue().state;
        final ArrayList<TaskId> taskIds = new ArrayList<>(state.assignedTaskCount());
        final int numActiveTasks = state.activeTaskCount();
        taskIds.addAll(state.activeTasks());
        taskIds.addAll(state.standbyTasks());
        final int numConsumers = consumers.size();
        int i = 0;
        for (String consumer : consumers) {
            Map<TaskId, Set<TopicPartition>> standby = new HashMap<>();
            ArrayList<AssignedPartition> assignedPartitions = new ArrayList<>();
            final int numTaskIds = taskIds.size();
            for (int j = i; j < numTaskIds; j += numConsumers) {
                TaskId taskId = taskIds.get(j);
                if (j < numActiveTasks) {
                    for (TopicPartition partition : partitionsForTask.get(taskId)) {
                        assignedPartitions.add(new AssignedPartition(taskId, partition));
                    }
                } else {
                    Set<TopicPartition> standbyPartitions = standby.get(taskId);
                    if (standbyPartitions == null) {
                        standbyPartitions = new HashSet<>();
                        standby.put(taskId, standbyPartitions);
                    }
                    standbyPartitions.addAll(partitionsForTask.get(taskId));
                }
            }
            Collections.sort(assignedPartitions);
            List<TaskId> active = new ArrayList<>();
            List<TopicPartition> activePartitions = new ArrayList<>();
            for (AssignedPartition partition : assignedPartitions) {
                active.add(partition.taskId);
                activePartitions.add(partition.partition);
            }
            // finally, encode the assignment before sending back to coordinator
            assignment.put(consumer, new Assignment(activePartitions, new AssignmentInfo(active, standby, partitionsByHostState).encode()));
            i++;
        }
    }
    return assignment;
}

Example 2 with StickyTaskAssignor

use of org.apache.kafka.streams.processor.internals.assignment.StickyTaskAssignor in project apache-kafka-on-k8s by banzaicloud.

the class StreamsPartitionAssignor method assign.

/*
     * This assigns tasks to consumer clients in the following steps.
     *
     * 0. check all repartition source topics and use internal topic manager to make sure
     *    they have been created with the right number of partitions.
     *
     * 1. using user customized partition grouper to generate tasks along with their
     *    assigned partitions; also make sure that the task's corresponding changelog topics
     *    have been created with the right number of partitions.
     *
     * 2. using TaskAssignor to assign tasks to consumer clients.
     *    - Assign a task to a client which was running it previously.
     *      If there is no such client, assign a task to a client which has its valid local state.
     *    - A client may have more than one stream threads.
     *      The assignor tries to assign tasks to a client proportionally to the number of threads.
     *    - We try not to assign the same set of tasks to two different clients
     *    We do the assignment in one-pass. The result may not satisfy above all.
     *
     * 3. within each client, tasks are assigned to consumer clients in round-robin manner.
     */
@Override
public Map<String, Assignment> assign(final Cluster metadata, final Map<String, Subscription> subscriptions) {
    // construct the client metadata from the decoded subscription info
    final Map<UUID, ClientMetadata> clientsMetadata = new HashMap<>();
    int minUserMetadataVersion = SubscriptionInfo.LATEST_SUPPORTED_VERSION;
    for (final Map.Entry<String, Subscription> entry : subscriptions.entrySet()) {
        final String consumerId = entry.getKey();
        final Subscription subscription = entry.getValue();
        final SubscriptionInfo info = SubscriptionInfo.decode(subscription.userData());
        final int usedVersion = info.version();
        if (usedVersion > SubscriptionInfo.LATEST_SUPPORTED_VERSION) {
            throw new IllegalStateException("Unknown metadata version: " + usedVersion + "; latest supported version: " + SubscriptionInfo.LATEST_SUPPORTED_VERSION);
        }
        if (usedVersion < minUserMetadataVersion) {
            minUserMetadataVersion = usedVersion;
        }
        // create the new client metadata if necessary
        ClientMetadata clientMetadata = clientsMetadata.get(info.processId());
        if (clientMetadata == null) {
            clientMetadata = new ClientMetadata(info.userEndPoint());
            clientsMetadata.put(info.processId(), clientMetadata);
        }
        // add the consumer to the client
        clientMetadata.addConsumer(consumerId, info);
    }
    log.debug("Constructed client metadata {} from the member subscriptions.", clientsMetadata);
    // ---------------- Step Zero ---------------- //
    // parse the topology to determine the repartition source topics,
    // making sure they are created with the number of partitions as
    // the maximum of the depending sub-topologies source topics' number of partitions
    final Map<Integer, InternalTopologyBuilder.TopicsInfo> topicGroups = taskManager.builder().topicGroups();
    final Map<String, InternalTopicMetadata> repartitionTopicMetadata = new HashMap<>();
    for (final InternalTopologyBuilder.TopicsInfo topicsInfo : topicGroups.values()) {
        for (final InternalTopicConfig topic : topicsInfo.repartitionSourceTopics.values()) {
            repartitionTopicMetadata.put(topic.name(), new InternalTopicMetadata(topic));
        }
    }
    boolean numPartitionsNeeded;
    do {
        numPartitionsNeeded = false;
        for (final InternalTopologyBuilder.TopicsInfo topicsInfo : topicGroups.values()) {
            for (final String topicName : topicsInfo.repartitionSourceTopics.keySet()) {
                int numPartitions = repartitionTopicMetadata.get(topicName).numPartitions;
                // try set the number of partitions for this repartition topic if it is not set yet
                if (numPartitions == UNKNOWN) {
                    for (final InternalTopologyBuilder.TopicsInfo otherTopicsInfo : topicGroups.values()) {
                        final Set<String> otherSinkTopics = otherTopicsInfo.sinkTopics;
                        if (otherSinkTopics.contains(topicName)) {
                            // use the maximum of all its source topic partitions as the number of partitions
                            for (final String sourceTopicName : otherTopicsInfo.sourceTopics) {
                                final Integer numPartitionsCandidate;
                                // map().join().join(map())
                                if (repartitionTopicMetadata.containsKey(sourceTopicName)) {
                                    numPartitionsCandidate = repartitionTopicMetadata.get(sourceTopicName).numPartitions;
                                } else {
                                    numPartitionsCandidate = metadata.partitionCountForTopic(sourceTopicName);
                                    if (numPartitionsCandidate == null) {
                                        repartitionTopicMetadata.get(topicName).numPartitions = NOT_AVAILABLE;
                                    }
                                }
                                if (numPartitionsCandidate != null && numPartitionsCandidate > numPartitions) {
                                    numPartitions = numPartitionsCandidate;
                                }
                            }
                        }
                    }
                    // another iteration is needed
                    if (numPartitions == UNKNOWN) {
                        numPartitionsNeeded = true;
                    } else {
                        repartitionTopicMetadata.get(topicName).numPartitions = numPartitions;
                    }
                }
            }
        }
    } while (numPartitionsNeeded);
    // ensure the co-partitioning topics within the group have the same number of partitions,
    // and enforce the number of partitions for those repartition topics to be the same if they
    // are co-partitioned as well.
    ensureCopartitioning(taskManager.builder().copartitionGroups(), repartitionTopicMetadata, metadata);
    // make sure the repartition source topics exist with the right number of partitions,
    // create these topics if necessary
    prepareTopic(repartitionTopicMetadata);
    // augment the metadata with the newly computed number of partitions for all the
    // repartition source topics
    final Map<TopicPartition, PartitionInfo> allRepartitionTopicPartitions = new HashMap<>();
    for (final Map.Entry<String, InternalTopicMetadata> entry : repartitionTopicMetadata.entrySet()) {
        final String topic = entry.getKey();
        final int numPartitions = entry.getValue().numPartitions;
        for (int partition = 0; partition < numPartitions; partition++) {
            allRepartitionTopicPartitions.put(new TopicPartition(topic, partition), new PartitionInfo(topic, partition, null, new Node[0], new Node[0]));
        }
    }
    final Cluster fullMetadata = metadata.withPartitions(allRepartitionTopicPartitions);
    taskManager.setClusterMetadata(fullMetadata);
    log.debug("Created repartition topics {} from the parsed topology.", allRepartitionTopicPartitions.values());
    // ---------------- Step One ---------------- //
    // get the tasks as partition groups from the partition grouper
    final Set<String> allSourceTopics = new HashSet<>();
    final Map<Integer, Set<String>> sourceTopicsByGroup = new HashMap<>();
    for (final Map.Entry<Integer, InternalTopologyBuilder.TopicsInfo> entry : topicGroups.entrySet()) {
        allSourceTopics.addAll(entry.getValue().sourceTopics);
        sourceTopicsByGroup.put(entry.getKey(), entry.getValue().sourceTopics);
    }
    final Map<TaskId, Set<TopicPartition>> partitionsForTask = partitionGrouper.partitionGroups(sourceTopicsByGroup, fullMetadata);
    // check if all partitions are assigned, and there are no duplicates of partitions in multiple tasks
    final Set<TopicPartition> allAssignedPartitions = new HashSet<>();
    final Map<Integer, Set<TaskId>> tasksByTopicGroup = new HashMap<>();
    for (final Map.Entry<TaskId, Set<TopicPartition>> entry : partitionsForTask.entrySet()) {
        final Set<TopicPartition> partitions = entry.getValue();
        for (final TopicPartition partition : partitions) {
            if (allAssignedPartitions.contains(partition)) {
                log.warn("Partition {} is assigned to more than one tasks: {}", partition, partitionsForTask);
            }
        }
        allAssignedPartitions.addAll(partitions);
        final TaskId id = entry.getKey();
        Set<TaskId> ids = tasksByTopicGroup.get(id.topicGroupId);
        if (ids == null) {
            ids = new HashSet<>();
            tasksByTopicGroup.put(id.topicGroupId, ids);
        }
        ids.add(id);
    }
    for (final String topic : allSourceTopics) {
        final List<PartitionInfo> partitionInfoList = fullMetadata.partitionsForTopic(topic);
        if (!partitionInfoList.isEmpty()) {
            for (final PartitionInfo partitionInfo : partitionInfoList) {
                final TopicPartition partition = new TopicPartition(partitionInfo.topic(), partitionInfo.partition());
                if (!allAssignedPartitions.contains(partition)) {
                    log.warn("Partition {} is not assigned to any tasks: {}", partition, partitionsForTask);
                }
            }
        } else {
            log.warn("No partitions found for topic {}", topic);
        }
    }
    // add tasks to state change log topic subscribers
    final Map<String, InternalTopicMetadata> changelogTopicMetadata = new HashMap<>();
    for (final Map.Entry<Integer, InternalTopologyBuilder.TopicsInfo> entry : topicGroups.entrySet()) {
        final int topicGroupId = entry.getKey();
        final Map<String, InternalTopicConfig> stateChangelogTopics = entry.getValue().stateChangelogTopics;
        for (final InternalTopicConfig topicConfig : stateChangelogTopics.values()) {
            // the expected number of partitions is the max value of TaskId.partition + 1
            int numPartitions = UNKNOWN;
            if (tasksByTopicGroup.get(topicGroupId) != null) {
                for (final TaskId task : tasksByTopicGroup.get(topicGroupId)) {
                    if (numPartitions < task.partition + 1)
                        numPartitions = task.partition + 1;
                }
                final InternalTopicMetadata topicMetadata = new InternalTopicMetadata(topicConfig);
                topicMetadata.numPartitions = numPartitions;
                changelogTopicMetadata.put(topicConfig.name(), topicMetadata);
            } else {
                log.debug("No tasks found for topic group {}", topicGroupId);
            }
        }
    }
    prepareTopic(changelogTopicMetadata);
    log.debug("Created state changelog topics {} from the parsed topology.", changelogTopicMetadata.values());
    // ---------------- Step Two ---------------- //
    // assign tasks to clients
    final Map<UUID, ClientState> states = new HashMap<>();
    for (final Map.Entry<UUID, ClientMetadata> entry : clientsMetadata.entrySet()) {
        states.put(entry.getKey(), entry.getValue().state);
    }
    log.debug("Assigning tasks {} to clients {} with number of replicas {}", partitionsForTask.keySet(), states, numStandbyReplicas);
    final StickyTaskAssignor<UUID> taskAssignor = new StickyTaskAssignor<>(states, partitionsForTask.keySet());
    taskAssignor.assign(numStandbyReplicas);
    log.info("Assigned tasks to clients as {}.", states);
    // ---------------- Step Three ---------------- //
    // construct the global partition assignment per host map
    final Map<HostInfo, Set<TopicPartition>> partitionsByHostState = new HashMap<>();
    if (minUserMetadataVersion == 2) {
        for (final Map.Entry<UUID, ClientMetadata> entry : clientsMetadata.entrySet()) {
            final HostInfo hostInfo = entry.getValue().hostInfo;
            if (hostInfo != null) {
                final Set<TopicPartition> topicPartitions = new HashSet<>();
                final ClientState state = entry.getValue().state;
                for (final TaskId id : state.activeTasks()) {
                    topicPartitions.addAll(partitionsForTask.get(id));
                }
                partitionsByHostState.put(hostInfo, topicPartitions);
            }
        }
    }
    taskManager.setPartitionsByHostState(partitionsByHostState);
    // within the client, distribute tasks to its owned consumers
    final Map<String, Assignment> assignment = new HashMap<>();
    for (final Map.Entry<UUID, ClientMetadata> entry : clientsMetadata.entrySet()) {
        final Set<String> consumers = entry.getValue().consumers;
        final ClientState state = entry.getValue().state;
        final List<List<TaskId>> interleavedActive = interleaveTasksByGroupId(state.activeTasks(), consumers.size());
        final List<List<TaskId>> interleavedStandby = interleaveTasksByGroupId(state.standbyTasks(), consumers.size());
        int consumerTaskIndex = 0;
        for (final String consumer : consumers) {
            final Map<TaskId, Set<TopicPartition>> standby = new HashMap<>();
            final ArrayList<AssignedPartition> assignedPartitions = new ArrayList<>();
            final List<TaskId> assignedActiveList = interleavedActive.get(consumerTaskIndex);
            for (final TaskId taskId : assignedActiveList) {
                for (final TopicPartition partition : partitionsForTask.get(taskId)) {
                    assignedPartitions.add(new AssignedPartition(taskId, partition));
                }
            }
            if (!state.standbyTasks().isEmpty()) {
                final List<TaskId> assignedStandbyList = interleavedStandby.get(consumerTaskIndex);
                for (final TaskId taskId : assignedStandbyList) {
                    Set<TopicPartition> standbyPartitions = standby.get(taskId);
                    if (standbyPartitions == null) {
                        standbyPartitions = new HashSet<>();
                        standby.put(taskId, standbyPartitions);
                    }
                    standbyPartitions.addAll(partitionsForTask.get(taskId));
                }
            }
            consumerTaskIndex++;
            Collections.sort(assignedPartitions);
            final List<TaskId> active = new ArrayList<>();
            final List<TopicPartition> activePartitions = new ArrayList<>();
            for (final AssignedPartition partition : assignedPartitions) {
                active.add(partition.taskId);
                activePartitions.add(partition.partition);
            }
            // finally, encode the assignment before sending back to coordinator
            assignment.put(consumer, new Assignment(activePartitions, new AssignmentInfo(minUserMetadataVersion, active, standby, partitionsByHostState).encode()));
        }
    }
    return assignment;
}