Kafka consumer group partition assignment strategy. Monitoring and Logging Having robust .
Kafka consumer group partition assignment strategy. One of the crucial aspects of Kafka is how it distributes partitions among consumers in a consumer group. Dec 19, 2018 · I'm confused to what degree partition assignment is a client side concern partition. Oct 14, 2025 · Apache Kafka is a distributed streaming platform that has gained significant popularity in the world of data streaming and event-driven architectures. Dec 17, 2023 · Partition assignment strategies Kafka provides several values for partition/consumer assignments, the last one is the incremental cooperative rebalancing: RangeAssignor: assign partitions on a per Oct 14, 2025 · Table of Contents Core Concepts Typical Usage Example Common Practices Best Practices Conclusion FAQ References Core Concepts Partition Assignment in Kafka In Kafka, a topic is divided into multiple partitions, and a consumer group consists of one or more consumers. Jun 21, 2020 · RoundRobinAssignor策略对应的partition. The consumer group is a crucial part of Kafka applications Oct 14, 2025 · Kafka uses a partition assignment strategy to distribute partitions among consumers in a consumer group. strategy property on classic consumer is replaced in the new consumer rebalance protocol by the server-side group. Use a hashing strategy for keys in custom partitioners. Default: [RangePartitionAssignor, RoundRobinPartitionAssignor] max_poll_records (int) – The maximum number of records returned in a single call to poll(). PARTITION_ASSIGNMENT_STRATEGY_CONFIG) in the properties provided to the DefaultKafkaConsumerFactory. In conclusion, when implementing a Kafka-based application, it's essential to carefully consider the trade-offs between using consumer groups and partitions. consumer. Learn how the consumer group protocol decouples the processing of events from storage in Kafka. Kafka提供了多种分区策略如 RoundRobin （轮询）、 Range （按范围），可通过参数partition. Similarly, if you remove a consumer or it fails, Kafka reassigns its partitions to other remaining active consumers. Learn how to handle Kafka topic partitioning and develop a winning Kafka partition strategy. The coordinator uses an internal Kafka topic called __consumer_offsets to keep track of group metadata. This comprehensive guide covers essential concepts, triggers, mechanisms, and protocols of Kafka rebalancing. strategy: Controls how partitions are assigned to consumers (e. The default strategy is the "RangeAssignor" which assigns partitions to consumers in a range - based manner. A new consumer will start consuming messages from partitions according to the configured consumer partition strategies (explained later). Apr 27, 2023 · kafka 2. This guide breaks down everything using simple examples, use cases, and visuals to help you understand Kafka at scale. To change the ConsumerPartitionAssignor, you can set the partition. Jun 1, 2022 · Kafka分区分配策略详解：Range策略按分区范围分配，可能导致负载不均；RoundRobin策略轮询分配更均衡，但要求消费者配置相同。文章对比两种策略实现原理及适用场景，帮助开发者优化Kafka消费组性能。 Aug 21, 2024 · Solving Kafka Rebalancing Problems Apache Kafka is a robust distributed messaging system, widely used for building real-time data pipelines and streaming applications. Jul 8, 2025 · Note that they are both sticky, and the goal is to minimize partition movements. 0 4 pods on kubernetes running kafka consumers consumer properties: max poll interval of 5 minutes, session of 45 seconds all consumers "subscribe" to the same topic, using a consumer group. Members of the consumer group subscribe to the topics they are interested in and forward their subscriptions to a Kafka broker serving as the group coordinator. The last point is what makes Kafka highly available - a cluster is composed by multiple brokers with replicated data per topic and Partition Assignor ¶ Kafka Streams ¶ Kafka Streams distributes work across multiple processes by using the consumer group protocol introduced in Kafka 0. apache. One of the critical aspects of Kafka’s operation is the concept of rebalancing, which occurs when Kafka adjusts the distribution of partitions among consumers in a consumer group. A balanced consumer setup in Kafka ensures that partitions of a topic are evenly distributed among the consumers in a group, which helps in . Jun 1, 2025 · If you’ve ever felt confused by Kafka’s partitions, keys, and consumer groups — you’re not alone. In this post I will Oct 22, 2015 · The new consumer currently relies on a server-side coordinator to negotiate the set of consumer processes that form the group and to assign the partitions to each member of the consumer group per some assignment strategy which group members must agree on. An alternative is to implement a custom partition assignment strategy that considers the consumer group lag while assigning partitions. During a rebalance, Kafka may need to pause data consumption temporarily. librdkafka is similar, but obviously cannot load arbitrary Java classes for partition assignments. The partition. This assignor would use a different algorithm than the roundrobin assignor, tracking the number of partitions assigned to each consumer group member, and having the partition assignment assign each partition to the least-loaded eligible In this video exercise, explore how the consumer group protocol controls a Kafka consumer group's behavior as consumers join and leave the group. strategy) is now deprecated. Additionally, custom strategies can be Then, each consumer is assigned one topic or partition. Nov 14, 2024 · Ever wondered what happens when you have multiple consumer groups reading from the same Kafka topic? ️ Scenario: You have one topic with several partitions, and you’re using two consumer Jan 9, 2025 · Kafka Consumer Architecture 2025: Deep dive into consumer groups, the revolutionary KIP-848 rebalance protocol, and modern offset management. Kafka lets you choose how producers should publish messages to partitions and how partitions are assigned to consumers. Partition strategies are supported by the following classes: Oct 14, 2025 · In the world of big data and real - time data processing, Apache Kafka has emerged as a leading distributed streaming platform. 7 The maximum number of active task for a sink connector is equal to the topic with the biggest number of partitions to consume because it's using the RangeAssignor partition assignment strategy (it's not related to the number of partitions of the topic offset. Default: 500 Sep 18, 2024 · Apache Kafka’s partitioning strategy plays a key role in distributing data across brokers and enabling parallel processing. Kafka consumers play a crucial role in consuming data from Kafka topics. (For simplicity of implementation) the assignor is allowed to assign a given topic-partition to any consumer instance and thread-id within that instance. If consumers are part of different consumer groups you cannot avoid duplication, it's how Kafka works. Mar 19, 2021 · Additionally, it seems when a consumer leaves the group, partitions are being shuffled between the remaining consumers (I would expect that cooperative rebalance would only assign partitions from the consumer that left without revoking any). The consumers in a group divides the topic partitions as fairly amongst themselves as possible by establishing that each partition is only consumed by a single consumer from the group. This method is crucial for efficiently distributing Kafka topic partitions among consumers while respecting configured priorities and dynamic assignment strategies. Oct 11, 2024 · No commit option: Partitions do not provide a commit option, which means you cannot mark a specific point in the message stream as consumed. strategy: Determines the partition assignment strategy used by the consumer. What is Apache Kafka? Kafka is a distributed event streaming platform that allows microservices and systems to communicate asynchronously and in real-time using topics May 11, 2024 · Discover the power of partitions in Kafka topics and learn how to consume messages from partitioned topics using Spring Boot. Jan 3, 2024 · Partition Assignment策略：在Consumer Group启动时，Group Coordinator负责为Consumer Group的每个成员分配要消费的Partition。 这个分配是根据Partition Assignment策略来完成的，Kafka提供了不同的策略来实现不同的分配方式，例如Round Robin、Range、或自定义分配策略。 Dec 17, 2024 · Dive deep into the critical process of Apache Kafka rebalancing, which ensures efficient and balanced data processing across consumer instances. Mar 14, 2023 · This video explains the Secrets of Kafka Partition Assignment Strategy across multiple consumers within same Consumer Group. 9. strategy consumer property (ConsumerConfig. Kafka's default rack-aware strategy usually suffices. Monitor partition traffic using Kafka tools and rebalance partitions if necessary. Oct 31, 2019 · The Kafka consumer groups concept is a great and easy-to-approach abstraction over multi-instance consumption of records from topics. Consumer Group中的consumer发生了新增或者 Nov 6, 2020 · route message within a topic to the appropriate partition based on partition strategy, assignment of partitions to consumer within consumer groups, partition rebalancing, replication of logs with other brokers. (Consumer level) max. The Jan 24, 2024 · There’s more than one way to partition a Kafka topic. The latest StickyAssignor strategy Moving the ownership of a partition from one consumer to another is called rebalance Aug 25, 2022 · New to Kafka? Read our beginner's guide to Kafka consumers and learn how to process data from Kafka topics, and configure a Consumer Group. strategy. Jun 21, 2025 · (Topic level) partition. The partition strategy affects the message ordering, consumer scaling, and overall system behavior. strategy property and defining the qualified class name of the assignor to use. Jun 18, 2017 · The prototype prototype implementation achieves this by creating an additional KafkaConsumer joined to the consumer group for which assignment is being performed. Kafka has two allocation strategies, one is roundrobin and the other is range. strategy进行配置。 一般情况下，在topic和消费组不发生变化，Kafka会根据topic分区、消费组情况等确定分区策略，但是当发生以下情况时，会触发Kafka的分区重分配： 1. This interface is used to define custom partition assignment for use in KafkaConsumer. 0 it may be more appropriate to obtain offsets via the new Admin API. strategy consumer config parameter). Nov 25, 2024 · Explore the intricacies of Kafka consumer group rebalancing, partition ownership, and strategies to handle rebalances effectively in distributed systems. declaration: package: org. remote. 11. This blog post aims to provide an in - depth understanding of Feb 3, 2017 · It means that this assignment strategy can be configured on a consumer (see partition. PARTITION_ASSIGNMENT_STRATEGY_CONFIG) configuration property when StreamsConfig is requested for the configuration for the main Kafka Consumer (when StreamThread is requested to create a new StreamThread instance and Default: 300000 partition_assignment_strategy (list) – List of objects to use to distribute partition ownership amongst consumer instances when group management is used. The Group coordinator facilitates partition assignment and helps maintain balance across the group when membership changes occur and as topic metadata changes. Therefore, round-robin assignment is allowed only if: a) Every topic has the same number of streams within a consumer instance b) The set of subscribed topics is identical for every consumer instance within the group. Possible Options for this config are Range, RoundRobin, StickyAssignor, and YourOwnCustomPartitioner. Discover the basics, custom strategies, their impact on performance, and the best practices for efficient data processing. First, it guarantees an assignment that is as balanced as possible, meaning either: the numbers of topic partitions assigned to consumers differ by at most one; or each consumer that has 2+ fewer topic partitions than some other consumer cannot get any of those topic partitions transferred to it. May 4, 2023 · To configure the partition assignment strategy, you must set the partition. RoundRobinAssignor。 使用RoundRobin策略有两个前提条件必须满足： You can configure a consumer group’s assignment strategy by using the partition. Apr 26, 2024 · Partition assignment to consumer groups Consumer rebalancing You can add or remove consumers from a consumer group at run time. A Kafka consumer diagram helps in visualizing the various components and interactions involved in the consumer process. Understanding how Kafka delivers messages across partitions is crucial for building reliable distributed systems. kafka kafka-clients version: 3. bytes: Limits the amount of data fetched from a partition in a single request. Second, it preserved as many existing assignment as A Kafka partition key is a value that a producer uses to direct messages to a specific partition in a Kafka topic. fetch. The default strategy is the RangeAssignor, which divides the partitions of a topic among the consumers in the group based on the range of partition indices. Explanation: Oct 17, 2018 · This assignment strategy, which is implemented for the new consumer, would add a StickyAssignor class that can be used as org. Kafka elects one of the consumers in the consumer group to use its partition assignment strategy to assign partitions to the consumers in the group. Jun 23, 2024 · We will delve deeply into the workings of the Kafka consumer, including concepts such as Consumer Groups, Consumer Leader & Coordinator, partition assignment strategies, and the internal of the Sep 6, 2024 · Priority Partition Assignment Strategy In Kafka, when a consumer group needs to assign partitions to its consumers, it invokes the assign method implemented in a custom partition assignor class like PriorityAssignor. It seems like when you add consumers in a group, however, Kafka (or at least, kafka-python) assumes that you want the group coordinator to do all assignments. consumer, class: ConsumerConfig Oct 10, 2025 · The subscription set denotes the desired topics to consume and this set is provided to the partition assignor (one of the elected group members) for all clients which then uses the configured partition. For example, say I have one kafka topic with 100 partitio Jul 20, 2025 · The `org. Monitoring and Logging Having robust Select an appropriate partition assignment strategy, which determines how Kafka topic partitions are distributed among consumer instances in a group. Nov 10, 2023 · Kafka provides several configuration settings that control message distribution and consumption: partition. Our A Kafka partition strategy refers to the method used to distribute messages across multiple partitions within a Kafka topic. How to reproduce Bring up a consumer and let it start consuming. assignment. Covers load balancing, failover strategies, threading models, and best practices for building resilient consumer applications with KRaft Jul 6, 2025 · Kafka uses a partition assignment strategy to decide which partitions each consumer in the group will consume from. Apr 1, 2025 · What happens behind the scenes when a consumer group is created, when members join or leave, or when partitions are reassigned? In this blog, we’ll break down the mechanics of Kafka consumer groups, the role of the group coordinator, and the steps involved in group startup and partition assignment. As a result, the balanced spread of partitions amongst consumers one would expect, is not happening. assignor on the consumer. This is known as group rebalancing. Each consumer can read from zero, one, or more than one partition. strategy property on your consumer configurations. The previous configuration for setting partition assignment strategies (partition. Topic partitions can be increased to let more consumers work on a topic, having more consumers than the number partitions is not useful. clients. kafka. StreamsPartitionAssignor (as a fully-qualified class name) is registered under partition. Kafka’s own developer community is working on an implementation here. May 14, 2024 · Explore the best Kafka partition strategies for optimal data distribution and processing efficiency. When you configure Kafka consumers, the choice of assignment strategy is important and depends on the specific requirements for partition balancing, consumer group stability, and rebalance behavior. Jan 22, 2024 · Partition Rebalancing Let’s discuss consumer groups and strategies for rebalancing partitions. strategy and what part is handled by Kafka. So in total, this consumer group has 35 Jul 27, 2022 · We were trying out with RoundRobin assignment strategy config; created an application which subscribes with 2 topics ( say topic-1 and topic-2, each having 10 partitions ) and created 10 consumer objects per topic, so that aspiration is that we have got 20 consumer objects processing from each of the partitions (total 20 ) of 2 topics; so far Oct 28, 2024 · Kafka provides several partition assignment strategies: RangeAssignor, RoundRobinAssignor, and StickyAssignor, with RangeAssignor being the default. Jan 7, 2022 · Integrating with Kafka usually starts with subscribing your consumers to Kafka with default configuration and it just works. When consumers join or leave a group, partitions are reassigned. strategy (ConsumerConfig. For example, if there are 10 partitions and 5 consumers, each consumer would be assigned 2 consecutive partitions [4]. This blog post aims to provide an in - depth understanding of Kafka Oct 14, 2025 · Apache Kafka is a distributed streaming platform that has gained significant popularity in the big data and real - time processing ecosystem. partitions) An active task is a task with partition attributed in the consumer-group of the sink connector Jan 22, 2025 · Update Partition Assignment Strategy: If using a custom assignment strategy, ensure it is optimized for your use case. Feb 8, 2025 · How Kafka Manages Consumer Groups in Microservices Kafka assigns partitions to consumers within a consumer group using a partition assignment strategy. Jun 25, 2016 · All consumers in a consumer group are assigned a set of partitions, under two conditions : no two consumers in the same group have any partition in common - and the consumer group as a whole is assigned every existing partition. Feb 25, 2025 · Ensure the partitioning logic produces an even key distribution. strategy to assign the subscription sets's topics's partitions to the consumers, depending on their subscription. Consider using assign() over subscribe() for more control over partition assignment. strategy to CooperativeStickyAssignor 1024 Consumer groups Kafka consumers belonging to the same consumer group share a group id. RangeAssignor` is a built - in partition assignment strategy provided by Kafka. , RangeAssignor, StickyAssignor). Learn how Kafka 4. One topic has 20 partitions, another 10, and the last one 5. The elected group leader will use a strategy supported by The sticky assignor serves two purposes. Oct 8, 2025 · This design enables Kafka to scale horizontally while maintaining performance. Furthermore, each partition can only be assigned to a single consumer at a given time. While rebalancing is essential for maintaining There are multiple consumers in a consumer group, and a topic has multiple partitions, so partition allocation is bound to be involved, that is, to determine which consumer consumes that partition. Sep 20, 2017 · 3 I am trying to manually assign partitions to each consumer within a consumer group. id Setting partition. Discover best practices Jan 21, 2025 · I'm working on a kafka streams application that consumes from a consumer group with three topics. Mar 7, 2022 · Digging into the details of partition assignment in Kafka as well as implementing our own custom partition assignment system. The partition assignment changes as the group members change. strategy simply decides the order in which the partition will be distributed amongst the consumer instances in a given consumer group. The assignment strategy is configurable through the Jul 14, 2024 · In your case with 1 topic and 2 partitions (on 2 brokers), the two consumers each in one different consumer group, will get the same messages from all 2 partitions. This Apache Kafka partition structure plays a key role in system performance, as the choice of Kafka partition assignment strategy and use of an appropriate partition key directly impact how data is distributed and consumed. Oct 14, 2025 · Apache Kafka is a distributed streaming platform that allows you to publish and subscribe to streams of records. The goal of partition assignment is to distribute the partitions of a topic among the consumers in a consumer group so that each Jul 19, 2023 · The page you linked to describes Apache's Kafka library written in Java. Clients can control how partitions are assigned to available […] Jul 13, 2024 · Explore strategies for scaling Apache Kafka consumers effectively using consumer groups, including tips on partition rebalancing, horizontal scaling, partition assignment strategies, and performance monitoring. Some common strategies include: Consumer groups provide scalability by spreading workload across consumer instances. Checking the librdkafka configuration docs, you should set it to "roundrobin": partition. (Consumer level) Behavioral characteristics: Ordering: Records are strictly ordered within a Feb 29, 2016 · Provide a Fair Partition Assignor option for both the original high-level consumer and the new consumer. The PartitionAssignor class acts as the decision-maker within the Kafka architecture. 8 (server) and java org. Multiple consumer instances join a group, and Kafka automatically assigns each partition to exactly one consumer in the group. This reassignment process is known Apr 23, 2025 · The group coordinator, a role assigned to one of the Kafka brokers, orchestrates the rebalancing process. Learn everything you need to know about Kafka partition strategy. When a rebalance is triggered, the coordinator manages the redistribution of partitions, notifying consumers of their new assignments and ensuring a smooth transition from the old assignment to the new one. Learn what a Kafka consumer group ID is and how assigning one to Kafka consumers during configuration helps with detecting new data, work sharing, and data recovery. Let's see how different assignors work and what are their pros and cons. One of the key features of Kafka is its ability to handle multiple consumers efficiently through consumer groups. In a given consumer group, one partition can only be assigned to one consumer. A partition is a fundamental unit that represents a linear, ordered sequence of messages. 0. The `RangeAssignor` is one of the partition assignment strategies in Kafka. 0 eliminates rebalancing downtime, enables massive consumer groups, and introduces queue semantics. Offsets are then obtained via the Consumer API. more Jul 24, 2024 · Kafka operates on a pull-based approach, where the consumer drives the process, unlike RabbitMQ, which is producer-driven. What happens if a consumer does not call poll() within the specified timeout? Kafka assumes the consumer is dead and triggers a rebalance. It plays a vital role in determining which partitions of a topic should be assigned to each consumer within a consumer group. The number of topic partitions determines the maximum level of parallelism that you can achieve, as one partition can only be assigned to one consumer in a consumer group. StickyAssignor for the value of the consumer property partition. One of the key features of Kafka is its support for consumer groups, which allow multiple consumers to work together to consume messages from Kafka topics in a coordinated manner. strategy The name of one or more partition assignment strategies. The group coordinator uses a partition assignment strategy to assign partitions to consumers in the Kafka consumer group. If the user calls the subscribe() API, the Consumer knows that it is being directed to use Kafka's consumer group -based partition assignment. Bring up a second and let it rebalance. assignors configuration (uniform or range, the default is uniform). May 11, 2021 · In kafka-connect 2. In Kafka, the producer sends messages to partitions of topic, and Apr 23, 2025 · This is the default strategy, which assigns contiguous ranges of partitions to consumers in the same consumer group. Here's an example of how you can do this in Java using the Kafka consumer client: Feb 28, 2022 · In my previous article, we had discussed how Kafka works and went through some basic Kafka terminology. Nov 20, 2019 · When creating a new Kafka consumer, we can configure the strategy that will be used to assign the partitions amongst the consumer instances. Jan 4, 2024 · When a producer sends messages to a Kafka topic, Kafka organizes these messages into partitions using a specified partitioning strategy. In this article, we would go over how Partitions and Consumer Groups work in Kafka. Partitions… This is achieved by assigning the partitions in the topic to the consumers in the consumer group so that each partition is consumed by exactly one consumer in the group. If a partitions assignment was handled by a consumer group coordinator, it would be impossible to configure a custom assignment strategy without rebooting the broker. Once a message is produced, it is assigned to a particular partition based on the chosen partitioning strategy. Message ordering If absolute ordering within a topic is important, use a single-partition topic. assignors on the broker and the group. Handle Unbalanced Partitions: Make sure partition distribution is balanced among consumers. g. 2. Nov 13, 2024 · What Triggers a Consumer Group Rebalance? A consumer group rebalance occurs when there is a change in the set of consumers or partitions, which causes Kafka to stop processing messages temporarily Aug 27, 2021 · Dive into the world of Apache Kafka Partitioning Strategy. Mar 10, 2024 · This is part of my personal reading summary of the book — Kafka: The Definitive Guide. Jan 8, 2024 · A consumer group is a set of unique consumers associated with one or more topics. These are set with the new server-side group. The prototype targeted Kafka 0. strategy参数值为：org. storage. In certain cases, however, you might end up with a scenario where only a subset of all consumers in a group is assigned to any partitions. This is the first edition in 2017 and provides a complete overview for developing scalable streaming Apr 8, 2024 · Kafka 的分区分配策略（Partition Assignment Strategy）是决定如何将分区分配给消费者的重要组成部分。消费者组内的每个消费者都需要负责处理一定数量的分区，而分区分配策略决定了如何公平地、有效地分配这些分区，以实现负载均衡和高可用性。本文将深入探讨 Kafka 的分区分配策略、常见的分配算法 Aug 28, 2020 · partition. Dec 17, 2021 · Rebalance & Partition Assignment Strategies in Kafka In common architectures, applications need to use Kafka to read the messages that are written as consumption data. Jan 3, 2024 · Based on the user calling either assign() or subscribe(), a Consumer determines how topic partitions are to be assigned. Jul 9, 2023 · Kafka provides horizontal scalability through partitions and topic consumers. A list of class names or class types, ordered by preference, of supported partition assignment strategies that the client will use to distribute partition ownership amongst consumer instances when group management is used. However, after working a while with Kafka you will encounter various "weird" behaviors originating from rebalancing settings such as chosen assignor implementation. 10. partition. Learn about key configuration parameters, common issues, and advanced techniques to optimize rebalancing performance. In Kafka 0. Jun 21, 2025 · Consumer groups implement Kafka's load-balancing magic. 20 times faster! Kafka then uses the selected partition assignment strategy to assign partitions to each consumer in the group. ptjstohq0elgf178klrslmbxoscvblcnfpzi2ni7nf