Kafka consumer multiple topics java. This was an example of .
Kafka consumer multiple topics java Jan 10, 2024 · Learn how to create a Kafka listener and consume messages from a topic using Kafka's Consumer API. listener. utils. After some research, I found that Kafka by default uses Range assigner. Download the Source Code. 6. common. When fetching records from Kafka bootstrap servers, we can specify one consumer to subscribe to more than one topic. How Kafka Works The need to process data from different topics concurrently. By specifying a list of topics, you can consume messages from them simultaneously. asList() allows to subscribe the consumer to multiple topics. If yes can you show me? – Aug 10, 2022 · java -jar target/java-kafka-example-1. We can use the below Kafka command line tool. A Kafka consumer can subscribe to multiple topics. When multiple consumers are subscribed to a topic, Kafka behaves like a pub/sub model with messages being received by multiple consumers. This tutorial will walk you through the process of configuring a Kafka consumer to subscribe to multiple topics simultaneously using Java. edit: this also means you can get messages out of order if your single topic Consumer switches partitions for some reason. To create a Kafka consumer that listens to multiple topics, you can use the KafkaConsumer API provided by Kafka. Kafka message consumption; Kafka consumer Java; Related Guides ⦿ Java Array Find Missing Number: A Comprehensive Guide ⦿ Jdbc Get Insert Id: A Comprehensive Guide ⦿ Hibernate Persist JSON Object: A Comprehensive Guide ⦿ Understanding JUnit 5 ParameterResolutionException: Causes and Solutions ⦿ Java Byte to Integer Conversion: A Aug 19, 2021 · In the previous article, i wrote about how to change kafka consumer state at runtime. This can be done in the init function by passing a list of topics: camel. processing applications that can independently consume and process messages from the same Kafka topic. We would like to show you a description here but the site won’t allow us. Whether through the Kafka Consumer API, Spring Kafka, or Kafka CLI, these methods offer flexibility and scalability for efficiently managing Kafka topics in diverse applications. topics is taken from my property file and contains the comma separated topics to which my listener should listen to. C:\kafka>. AppInfoParser - Kafka commitId: b172a0a94f4ebb9f [Thread-1] INFO org. split(',')}" where kafka. A consumer can subscribe multiple topics. One of its key components is the Kafka consumer, which is responsible for reading data from topics. single threading, and learn to write multi-threaded Kafka consumers for effective parallel processing. concurrency or you can simply run multiple Java processes on the same machine or multiple machines with the same configs. These processes can either be running on the same machine or they can be distributed over many machines to provide scalability and fault tolerance for processing. This is useful for applications that need to consume from multiple topics and can handle the different types of data the topics will contain. We may still use the custom thread pool with the Kafka consumer concurrency feature as shown below (through the concurrency parameter). 概述. kafka. Mar 10, 2024 · Scaling with Consumer Groups: — When multiple consumers belong to the same consumer group and subscribe to a topic, each consumer in the group receives messages — To scale data consumption Jun 16, 2022 · The requirement provided here is on the very high level. g. Jun 16, 2024 · 1. You can have as many Topics as you want in Apache Kafka and the way to identify a Topic is by its name. . Spring boot doesn’t provide support for multiple Kafka consumer configurations through a property file but we can leverage existing Kafka properties to create a custom configuration to support multiple consumers. In partitioning a topic, Kafka breaks it into fractions and stores each of them in different nodes of its distributed system. We started with the Producer and Consumer configuration and continued with the different ways to add multiple listeners for the same topic. See full list on howtodoinjava. There are also lots of answers across SO that address consuming from multiple topics with the same Broker, and it isn’t always as simple as that. This was an example of Jan 8, 2024 · In this article, we learned how to configure multiple listeners for the same topic using the Spring Kafka library, looking at a practical example of a book library. Handle records from all subscribed topics in a single poll loop. Broker: Kafka server, part of a cluster. camel. Cluster: Group of brokers managing multiple topics. bat . Multithreading is “the ability of a central processing unit (CPU) (or a single core in a multi-core processor) to provide multiple threads of execution concurrently, supported by the May 30, 2024 · Step 7: Sending Messages to the Topic. I want to create 6 or 12 kafka consumers under the same consumer group. 2. \config\server. properties. Offsets are maintained by zookeeper, as kafka-server itself is stateless. Feb 19, 2021 · There are a few ways to do this, and unfortunately Spring-Boot and Spring-Kafka do not make it clear the best practice to implement this. Mar 16, 2022 · Spring Kafka multiple consumer for single topic consume different messages. Both the messages are posted to different topic. Aug 27, 2018 · I am seeing a random lag of consumer , although the topic has data my consumer fetches no records from topic and fetches sometimes. Oct 19, 2024 · In this enhanced version of the Kafka Streams approach, Kafka Streams instances read from multiple topics, process the data (joins, aggregations, filtering, etc. In an Apache Kafka consumer group, the number of partitions is the parallelism limit. Apr 30, 2023 · Scenario 4: Process in Multiple Threads. Jul 10, 2018 · Let's create consumers for that topic, you wan't to read the news and your sister or brother also, each one on your time, then every one needs a consumer group id, this way kafka will know that threads a,b,c are for one consumer group and the d,e,c are for the second consumer group, every consumer group will receive the same messages, process Consumer Groups and Topic Subscriptions Kafka uses the concept of consumer groups to allow a pool of processes to divide the work of consuming and processing records. Setup Jun 14, 2023 · The @KafkaListener and @KafkaHandler annotations are part of Spring for Apache Kafka integration. It would be great if you can tell us your actual requirement from the business logic implementation perspective. Each Kafka topic is divided into partitions. All the topics have a single partition. A separate Kafka consumer (or consumers) can then read from this topic and handle the writes to the database. Listening to multiple topics may impact Kafka’s performance. The first two methods are based on Kafka Consumer API and Spring Kafka and can be integrated into an existing application. Mar 19, 2025 · Producer: Sends messages to Kafka topics. "test-x", "tes The Confluent Parallel Consumer is an open-source Apache 2. Advantages: Jan 26, 2025 · Previously, we ran command-line tools to create Kafka “topics”: $ bin/kafka-topics. This structure offers flexibility and efficiency in various use cases. For a Java developer Hi, So I have a Java application that spins up multiple threads, and each thread starts a kafka consumer in a different consumer group, consuming from one partition of a kafka topic with 100 partitions (some consumers may share a partition, but still be in different consumer groups). 5000. In below example, I am have 2 consumer factory which will be accpet 2 different JSON messages (one is user type and other is Event type). Below is a step-by-step guide and code example to help you implement a Kafka consumer for multiple topics in Java. Suppose you have a topic with 12 partitions. We’ll learn the configurable properties that can directly impact how many messages the Kafka Consumer reads at once. When you subscribe to multiple topics with a single Consumer, that Consumer is assigned a topic/partition pair for each requested topic. Mar 22, 2018 · We are working on an application where we want to listen for more than one topics in Kafka. When I work out with a single topic instead of looping through three topics it is working but unable to reproduce. Consume multiple topics in one listener in spring boot kafka. The last one uses Kafka CLI and can be used to verify multiple topics quickly. But with the introduction of AdminClient in Kafka, we can now create topics programmatically. My case need to connect one Kafka topic to fetch data using spring boot this data having another Kafka topic name read this information and connect to new topic fetch the data and perform some business logic . create-consumer-backoff-max-attempts. create-consumer-backoff-interval. sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic mytopic. Step 1: Add Kafka Dependencies Jul 3, 2019 · I use @KafkaListener(topics = "#{'${kafka. 前两种方法基于 Kafka Consumer API 和 Spring Kafka，可以集成到现有应用程序中。 Jan 23, 2020 · In your example where a topic correlates to a table you should probably have a consumer per topic because if your consumer is consuming from many unrelated topics then the consumption will slow down. This ensures that Kafka can handle large amounts of data by spreading the load. Maximum attempts to create the kafka consumer (kafka-client), before eventually giving up and failing. Aug 11, 2018 · I am not able to listen the kafka topic (my case 2 topics) when there are multiple consumer. These challenges can be addressed with proper cluster configuration and by adding hardware. jar [Thread-1] INFO org. Jan 16, 2020 · If you have one consumer then there will be one thread (Kafka consumer is not thread safe), if you need paralellism you need to have more than one partition in topic and same number of consumers in the same consumer group. Long. ), and then write the processed output to a new Kafka topic. Partitions in a Kafka Topic. Then i started to think, what if I have a logic process that I want to apply for some kafka topics? Do I have Oct 18, 2022 · So a Kafka Topic is going to be pretty similar to what a table is in a database without all the constraints, so if you have many tables in a database you will have many topics in Apache Kafka. 2. Run the following command to send the JSON object from Kafka Topics. Feb 19, 2020 · The source kafka topic has 12 partitions. Setting up the Environment Feb 28, 2022 · But if you have a use case where you want multiple consumers to consume the same messages of a topic, then having multiple consumer groups subscribed to the topic, and adding consumers as per your Apr 8, 2024 · A consumer can subscribe to multiple topics at once by passing in the ID of each one in you’ve created a Kafka consumer in Java that streams records from the Consumer Group: Kafka consumer group that the Data Collector belongs to. Finally, we’ll explore how adjusting these settings affects the Consumer‘s behavior. That number of fractions is determined by us or by the cluster default configurations. This example is pretty simple but Jul 2, 2020 · Thank you @Salavat Yalalo ! I am able to create multiple consumers but how do we know which consumer has handled/read the message from the topic? Will there be any consumer id printed in the logs? I see "[ntainer#0-5-C-1]" in your answer and I assume somewhere in the logs the consumer id(If exists) is getting printed. We need to add the KafkaAdmin Spring bean, which will automatically add Mar 31, 2017 · Here is a very simple example. Summary. They provide convenient ways to consume and handle messages from Kafka topics. You can read more about this structure in Feb 3, 2022 · The first time any new-to-Kafka engineer tries to do anything more complex than a simple read-quick process-write, they inevitably need to work around the fact that the KafkaConsumer is not thread Jun 2, 2023 · To create a parallel consumer for Apache Kafka in a Java Spring Boot application, you can utilize the Spring Kafka library and leverage the May 2, 2023 · ️ In this video We demonstrates "How kafka producer consumer works on spring boot application along with multiple topics". AppInfoParser - Kafka version: 3. Click here to learn more about how to optimize a Kafka consumer. bat --broker-list localhost:9092 --topic NewTopic. How many consumers can Kafka have? Kafka can have multiple consumers subscribed to the same topic. Whenever a consumer consumes a message,its offset is commited with zookeeper to keep a future track to process each message only once. There is no use of Zookeeper in consumer side. could you please help me to write spring boot code. If you have 2 Kafka consumers with the same Group Id, they will both read 6 partitions, meaning they will read different set of partitions = different set of messages. Partition: Ordered, immutable message sequence in a topic. All the topic names will have a common prefix e. 0-SNAPSHOT-jar-with-dependencies. 0-licensed Java library that enables you to consume from a Kafka topic with more parallelism than the number of partitions. \bin\windows\kafka-topics. apache. You can either set spring. Dec 25, 2018 · It depends on Group ID. Jan 8, 2024 · In this article, we learned how to configure multiple listeners for the same topic using the Spring Kafka library, looking at a practical example of a book library. So the consumers are smart enough and they will know which broker to read from and which partitions to read from. 在这个教程中，我们将学习如何使用 Kafka 订阅消费者到多个主题。 当相同的业务逻辑应用于多个主题时，这是常见的 Aug 30, 2023 · Make note of containerFactory passed in @KafkaListener annotation, which tells which consumer configuration to use. Therefore, Arrays. \bin\windows\kafka-server-start. Use the `subscribe` method of the `KafkaConsumer` class and pass a list of topic names to subscribe to multiple topics at once. Conclusion. Consuming is less efficient than producing so the most common use case is to split your topic into multiple partitions and have multiple consumers Oct 8, 2017 · Kafka only guarantees message order for a single topic/partition. This is useful when implementing the same functionality for several topics. Efficiently scaling application performance by consolidating data streams. topics}'. Jan 8, 2024 · Learn about Kafka consumer groups and their role in enhancing scalability by enabling multiple consumers to read from the same topic in parallel. Apr 24, 2025 · Kafka Consumer is used to reading data from a topic and remember a topic again is identified by its name. AppInfoParser - Kafka startTimeMs Code description. component. But may be, during start up u can add a logic to generate all the possible topics and assign to a variable, which can be later used as above. Solutions. bat --create --topic kafka-topic --bootstrap-server localhost:9092 --partitions 1 --replication-factor 1 Output: Type the message: Sep 9, 2024 · Kafka stores data in topics, and consumers subscribe to these topics to read the data. Kafka guarantees the order of the events within the same topic partition. Jul 6, 2024 · In this tutorial, we’ll explore how the Kafka Consumer retrieves messages from the broker. Jan 8, 2024 · In this article, we learned three different methods of subscribing a Kafka consumer to multiple topics. 1 [Thread-1] INFO org. There is no need for multiple threads, you can have one consumer, consuming from multiple topics. Apr 2, 2024 · This article has explored different approaches for configuring a Kafka consumer to subscribe to multiple topics. Pattern - Specify a regular expression that defines the topic names to read. asList() because may be the user wants to subscribe either to one or multiple topics. Consumer: Subscribes to topics and processes messages. Jun 17, 2019 · I am trying to consume messages from multiple topics using assign() method. Topic List: List of Kafka topics to read. To subscribe to all test topics, we can call: To read the message from a topic, we need to connect the consumer to the specified topic. Here, we have used Arrays. Topic Subscription Type: Method used to specify Kafka topics: Topics List - Specify a list of topics to read. A consumer can be subscribed through various subscribe API's. Now, we will use the Kafka producer to send the messages to the topic for testing. May 11, 2024 · Basically, Kafka implements a publisher-subscriber model where producer applications publish events to Kafka while consumer applications subscribe to these events. Learn how to implement and manage a Kafka consumer using Java, with detailed instructions and best practices. With my implementation, some times I am able to consume messages from all topics and other times from only one topic. So when you name a Topic it will need to have a Aug 13, 2020 · Explore the benefits and challenges of multi-threading vs. com Apache Kafka is a powerful tool for building real-time data pipelines and streaming applications. We will create a thread pool with the Java ExecutorService. // ----- // Sender // ----- @Configuration public class SenderConfig { @Bean public Map<String, Object> producerConfigs() { Map<String Mar 11, 2022 · Similarly, run your Apache Kafka server by using this command. May 11, 2024 · Kafka uses topic partitioning to improve scalability. 1. The delay in millis seconds to wait before trying again to create the kafka consumer (kafka-client). Subscribing to multiple topics using a regular expression is most commonly used in applications that replicate data between Kafka and another system. Nov 2, 2024 · Configuration for Multiple Consumer Groups in Kafka. Topic: Named stream of messages, split into partitions. \bin\windows\kafka-console-producer. Finally the last scenario. In this tutorial, we’ll learn how we can read data from the beginning of a Kafka topic using the Kafka Consumer API. Hence it will not assign all partitions always. Partitions allow Kafka to scale horizontally by distributing the data across multiple brokers. Step 6: Now run your spring boot application. need help to debug the issue and reproduce the same, Consumer Groups and Topic Subscriptions Kafka uses the concept of consumer groups to allow a pool of processes to divide the work of consuming and processing records. tgvkkcnwpsursatnplbrofxptowonknjezcwlmcxuvfisst