Kafka consumer multiple threads

Kafka consumer multiple threads. Happy Learning !! Nov 29, 2016 · Each "consume" (let say I have 2 topics to listen) method in the consumer application will be set with @StreamListener annotation and will be linked to specific topic. It means that for each consumer group, you will have one additional thread running. Multi-threaded Apache Kafka consumer model. if your topic contains 2 partitions and you start a consumer group group-A with 2 consumer instances then each one of them will be consuming public class KafkaConsumer<K,V> extends Object implements Consumer <K,V>. If you have less consumers than partitions, then they would be responsible for more than one partition each. msg = q. max. stream. What happens now is assuming you have 10 partitions of a topic, each partition will be submitted to its own thread and it will be processed concurrently. Oct 8, 2017 · Kafka only guarantees message order for a single topic/partition. While we are doing multithreading on 24. Then we configured one consumer and one producer per created topic. 2 TB of virtual memory. Since you have 8 partitions and 16 consumer threads Thread Safety. In Kafka, all records in a topic are grouped in partitions, which can be written to and read from independently without compromising the quality of the data. id> if you tried to re-use the same client. Only one thread (excluding the heartbeat thread) is created to fetch the records. Executors. Using commands in create-topics. If that's not the case, changing fetch. (If you have 2 app instances and 5 Dec 14, 2021 · The Logstash Kafka consumer handles group management and uses the default offset management strategy using Kafka topics. Split(*brokerList, ","), config) Then gets all the partitions for the desired topic: func getPartitions(c sarama. When you configure a Kafka Multitopic Consumer, you configure the consumer group name and the Jun 4, 2015 · 1. Java implementation. This client also interacts with the broker to allow groups of consumers Feb 28, 2022 · Case 1: If a new consumer joins the consumer group, rebalancing happens and each consumer is now assigned to a single partition (since we have equal number of partitions and consumers). The big issue with parallel processing within a partition is offset management. Consider using multiple threads per consumer. 0? 42. You can find code samples for the consumer in different languages in these guides. println("Aman" +record. Jun 12, 2018 · Usage of Java Kafka Consumer in multiple threads. concurrency controls the number of threads (default 1). Maximum value could be the maximum number of partitions. When I tried to describe the consumer group offsets using the below command, I noticed that the consumer groups public class KafkaConsumer<K,V> extends Object implements Consumer <K,V>. bat (Windows) 3. I want to implement the same thing in . 9 version and are having large number of messages pushed to specific partition within a kafka topic. 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. List<String> filteredMessages = new ArrayList<>(); TopicPartition tp = new TopicPartition("topicName", partitionNo); While the Java consumer does all IO and processing in the foreground thread, librdkafka-based clients (C/C++, Python, Go and C#) use a background thread. Right click -> Run As -> Java Application or use the shortcut: Alt+Shift+x, j to start the main method. The functions you would mostly need are: get. . If new instances join the group they will take over some partitions from other members of the group; if an instance dies, its The Logstash Kafka consumer handles group management and uses the default offset management strategy using Kafka topics. Working with ConsumerThread Class: Inside the run () method: Below is the complete code. Kafka consumer reading messages parallel. Offsets are maintained by zookeeper, as kafka-server itself is stateless. Nov 23, 2015 · Tested with kafka-clients 0. In the case an application needs to consume from multiple toppars one method is to create one application thread per toppar. The vast majority of libraries out there won't do that, because there are no set rules about what 'interrupting a thread' even means. The code here is a simple example on how this can be Oct 9, 2021 · 6. Consumer Group Multi-Threading. Open the MultipleConsumersMain. you have a topic with 16 partitions. By using multiple threads, you can increase throughput and reduce latency by processing more messages Dec 9, 2019 · For Java consumer API, No. In this tutorial, we’ll explain the features of Kafka Streams Apr 26, 2020 · Kafka consumer model from partitions, processes, to threads We’re going to use confluent-kafka-python to build our consumer. ThreadPoolExecutor(max_workers=10) as executor: Jun 4, 2023 · A Kafka topic with 4 partitions distributed across 4 consumers. The Kafka Multitopic Consumer origin reads data from multiple topics in an Apache Kafka cluster. poll. springframework. All good so far, but according to every other StackOverflow or Kafka doc I Jul 17, 2020 · When we use Thread myThread = new Thread(myConsumerRunnable); does that run in a > single thread or across multiple threads? Creating the Thread object does not start the new thread yet. partition. With Kafka individual records are not ack'd, we simply commit the offset of the last message processed. Jan 16, 2019 · 0. One should not have more consumer than the partitions. allow. ConsumerRecords<String, String> records = consumer. Running a Java Consumer in a separate thread allows you to perform other tasks in the main thread. If this is the first time configuring Kafka on Spring, a good place to start is with our introduction to Apache Kafka with Spring. foreachRDD(record -> {. By default, kafka reads and processes messages in a single-threaded May 9, 2019 · after creating the producer class, create a new MesssageSender object taking the producer record and producer as constructor args. In this tutorial, we’ll learn how to create a Kafka listener and consume messages from a topic using Kafka’s Consumer API. topics = true. Using the following code snippet to do so: kafkaListenerEndpointRegistry. Jan 10, 2024 · Overview. For every message in the batch, I am calling another API which has a rate limit. Sep 29, 2017 · Here's some sample code. Still with 1 thread per instance. Consumer) ([]int32, error) {. I'd like to increase numbers of the post consumers, let's say to have 5 consumers that will consume different (not the same) messages May 31, 2016 · Yes, you can create multiple consumers in multiple threads/processes (and even run them in parallel on different machines). Everything works as expected, both consumers get the message from the publisher on the topic, as shown in the following screen shot. Sorry the original code is too involved, so I created a sample here that I hope communicates what is happening. 160,000 threads and 1. Jul 10, 2018 · 20. The producer manages a single background thread that does I/O as well as a TCP connection to each of the brokers it . There are 2 possible models I’d like to mention in this post. if *partitions == "all" {. Sharing Kafka producer between Mar 22, 2021 · Create a queue (this would be shared across different threads) Keep one single thread to write to the queue (since writing is faster) Create a function to read from queue and do the processing. class KafkaWrapper(): def __init__(self): Jun 6, 2017 · Hi, Continuing the discussion from Multiple logstash reading from a single kafka topic: I have 6 Kafka Instances running. After that, we’ll test our implementation using the Producer API and Testcontainers. id inside the same JVM instance. This client also interacts with the broker to allow groups of May 25, 2022 · I assume that unless a rebalance occurs, each container thread will use a single kafka consumer that will read from a single partition (assuming concurrency = partition count). Nov 15, 2022 · In this spring Kafka multiple consumer java configuration example, we learned to creates multiple topics using TopicBuilder API. Further reading on this topic: KAFKA-3992 Mar 24, 2016 · 22. id, there will be no overlap. group=<group name>. You need to have at least as many partitions as the aggregate concurrency across all instances. And yes, you have to have the same group ID Apr 16, 2019 · You can set the stream configuration num. “python-kafka” also gives us the flexibility to commit whenever required. submit () to perform the task. Multithreaded producer consumer app on librdkafka. count()); Aug 13, 2020 · Multi-Threaded Message Consumption with the Apache Kafka Consumer. So I need a multi-thread consuming and producing for this requirement. 3. When using a concurrent message listener container, a single listener instance is invoked on all consumer threads. May 29, 2016 · 2. Logstash instances by default form a single logical group to subscribe to Kafka topics Each Logstash Kafka consumer can run multiple threads to increase read throughput. Thus, presumably, you interrupted it. management. Jan 27, 2016 · We are using Kafka 0. Your example program has a main thread and a consumer thread. Say you have three topics: t1, t2 and t3, each of which has two partitions. Jul 27, 2021 · I have multiple consumers to read from and was looking into adding different reader threads to read from the topic due to the volume of data. Partially because of this, Kafka (Java) producers/consumer are not thread-safe. How to create a Multithreaded Producer in Java. Since you can launch multiple consumer (within same consumer group). We’ll learn the configurable properties that can directly impact how many messages the Kafka Consumer reads at once. Multiple consumers with their own threads. 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 operating system. 9. invoke executorService. Call this function f. We have one consumer assigned per partition within this topic, and we are maintaining offset manually within the topic-partition in an outside datastore. create. Oct 12, 2016 · 7. This parallelization allows Karafka to achieve high throughput by distributing the work of processing messages across multiple threads. 2. poll() calls are separated by more than max. futures. The first step is to create a KafkaConsumer that can read messages from a topic. Yes, just follow the @KafkaListener JavaDocs: /**. Now, let’s consider the consumer(s) of this topic. You can use this to parallelize message handling in multiple threads. Create the Kafka Topic. You could use Kafka Streams API, however, where consumer threads can be configured. Mar 16, 2022 · By default, it seems that Spring Kafka launch 1 consumer thread per topic. When using a single thread, the consumer can only process one message at a time. Jul 30, 2020 · How to use multi-thread consumer in kafka 0. The second question is why when I set num. java. ExecutorService executorService =. If yes, you can just treat each consumer as a different consumer group. We want to create an application that takes a list of data files as an argument and does following. It is the responsibility of the user to ensure that multi-threaded access is properly Feb 28, 2022 · If all application instances are housed in a single server, then the server would need to be able to run at least 8000 x 20 = 160,000 threads simultaneously and use 60 x 20 = 1. org. While consuming each partition is consumed by exactly one consumer instance in the group . Now run the application and below is the output. poll() method. exe "cg1" and Consumer. threads config and will create a single KafkaConsumer per thread. sh (Linux) and create-topics. For 16 partitions you should have max 16 consumer listening to each partitions. Mar 18, 2023 · Step 3: Create a Consumer with Threads. Using multiple instances of rd_kafka_consume_batch() and/or rd_kafka_consume_batch_queue() APIs concurrently is not thread safe and will result in undefined behaviour. How to combine kafka python consumer and ThreadPoolExecutor? Hot Network Questions May 29, 2016 · It’s time to think about the multi-thread consumer model. There are several good Kafka Python clients you can find like kafka May 18, 2022 · 2. Comments are added inside the code to understand the code in more detail. Since each consumer group requires a separate connection and a thread, we do this concurrently. Kafka Consumer provides the basic functionalities to handle messages. Do make sure you are really OK with that. kafka. On the other hand I have 6 logstash Instances running for consuming messages from the topic. Sorted by: 7. Spawn multiple threads which run f. partitions(). 2 TB of virtual memory is very overwhelming for a single server. Also, every instance will only have one consumer thread. threads to a number greater to the number of consumers it didn't help. Jun 14, 2017 · Two consumers from Consumer Group tried to read the Kafka topic partition, but Kafka allows only one consumer from one consumer group can read the Kafka topic partition. * The topics for this listener. threads allows you to override the number of threads from 1. The producer is thread safe and should generally be shared among all threads for best performance. Kafka consumer for multiple topic. If it is not possible to make your listener thread-safe or adding synchronization would significantly reduce the benefit Kafka Consumer Poll Thread. GitHub Gist: instantly share code, notes, and snippets. extends Object. listener. with concurrent. There must be at least as many partitions as the concurrency (only one consumer in a group can consume from a a partition at the same time). bytes or max. Dec 19, 2018 · The Kafka consumer is NOT thread-safe. Case 2: If 4. Oct 24, 2021 · Generally, in a multi-threaded consumer implementation, the main consumer thread (the thread which is actually consuming from Kafka) delegates the consumed records processing to other threads. NewConsumer(strings. I am reading all 20+ topics (comma Feb 19, 2020 · 1. A multiprocess multithreaded Kafka consumer. <consumer>. Listeners, therefore, need to be thread-safe, and it is preferable to use stateless listeners. It may end up something like t3-1, t3-0, t2-0, t2-1, t1-0, t1-1. of(100, ChronoUnit. May 3, 2020 · The consumer is not thread-safe. Aug 30, 2020 · In the multi-threaded consumer mode, a single thread connects to Kafka and may get data from multiple / single partition (s). This code works fine if I use threading. A Kafka client that publishes records to the Kafka cluster. ”. * Expression must be resolved to the topic name. Suppose you have a topic with 12 partitions. pause(); When I call the pause, I also need to do a thread. # the topic. Using partitions is the way of being able to parallelize the consumption of a topic. //System. public List<String> searchMessages(String topicName, int partitionNo, long beginOffset, long endOffset) {. Step 4: Run the Application. The main consequence of this is that polling is totally safe when used from multiple threads. For high-load topics, there is always an IO overhead on transferring data from and to Kafka. consumer:type=app-info,id=<client. Thread instead of multiprocessing. 0? 8. The consumer maintains TCP connections to the necessary brokers to fetch data. Karafka is designed to efficiently handle a high volume of Kafka messages by leveraging a pool of worker threads. For example, if you are supplying three data files to the application, it Jan 8, 2024 · 1. set("num. Nov 1, 2022 · Multithreading is “the ability of a central processing unit (CPU) to provide multiple threads of execution concurrently, supported by the operating system. Dec 9, 2021 · How can do this with multiple threads to search all 20 partitons in parallel and have a final consolidated list. We have pretty the same need for a topic with 4 partitions, we created a consumer group with 2 members, and we assigned each member ( instance of our consumer) two partitions. How can I use Spring boot for developing a multi-thread consumer and producer? Sep 22, 2020 · And each thread will register a ShutDownHook so it can catch that the program is closing and gracefully close his Kafka consumer. auto. – dvlpr. The Kafka consumer is NOT thread-safe. This client transparently handles the failure of Kafka brokers, and transparently adapts as topic partitions it fetches migrate within the cluster. The solution for this issue is: cache the RDD. max. To run the above code, please follow the REST API endpoints created in Kafka JsonSerializer Example. Let's say if your topic has 4 partitions, you can set following: properties. class Producer {. Refer to Class KafkaProducer. There is no "number-of-consumer" config. newFixedThreadPool(MAX_THREAD); //Read the CSV file line by line. Nov 17, 2018 · The number of consumer threads is controlled by the container concurrency, not the number of topics. I created a topic with 18 Partitions and 3 as a replication factor. A common solution to the Kafka consumer throughput problem is to have a single threaded consumer which delegates the processing of There is no need for multiple threads, you can have one consumer, consuming from multiple topics. The partitions are distributed across the threads. To learn more about consumers in Kafka, see this free Apache Kafka 101 course. You would get a javax. Kafka assigns each topic partition to a single consumer within a consumer group. transformedMessages. Sep 9, 2015 · A consumer group can have multiple consumer instances running (multiple process with the same group-id). E. answered Jul 3, 2016 at 15:17. Apache Kafka is the most popular open-source distributed and fault-tolerant stream processing system. Kafka Streams create threads based on num. net. forEach(partition -> {. implements Consumer <K,V>. ms: (default 5 minutes) The maximum delay between invocations of poll () when using consumer group management. Multiple consumers with their own threads (Model #1) Single consumer, multiple worker processing threads (Model #2) Both of them have their own pros and cons. For more info about it search on Google: Kafka Consumer Groups. All network I/O happens in the thread of the application making the call. If you are using spring you can select how many members will be created by instances with this parameter: # For Kafka concurrency. Oct 14, 2023 · Partition-Consumer Mapping: Each partition in a Kafka topic can be consumed by only one consumer within a consumer group at any given time. It is the responsibility of the user to ensure that multi-threaded access is properly synchronized. With 2 instances, there is a load balancing and each instance listen to 25 partitions. A client that consumes records from a Kafka cluster. multiprocessing in kafka-python. ms time, then the consumer will be disconnected from the group. from multiprocessing import Process. Aug 3, 2020 · multiple application instances with same group id and each instance can have concurrent message listeners of 10 (for ex). We have at-least 20+ Kafka topics producing data into individual Kafka topics in AVRO format and each topic has been partitioned between 3 to 4 partitions. * Mutually exclusive with {@link #topicPattern()} and {@link #topicPartitions()}. get (timeout=60) # Set timeout to care for POSIX<3. Apr 21, 2021 · Set the concurrency property to get multiple threads. Managing the offsets can be tricky, unless you don't have reliability requirements and can afford to lose messages and/or get duplicates after a failure. Otherwise, the order of the messages cannot be guaranteed and the way the consumer offset is store will nto work. This is only recommended if you know about multi-threaded programming, so we will keep this page brief. consumer. The idea is to consume messages from few topics Oct 14, 2020 · I want to use the Transactional feature of Kafka consumer and producer in the project. 0, but the code related to this hasn't changed for two years. cloud. You can observe that the amount of code is very less, Only code we had to develop is the De-serializer for the Object Jul 6, 2021 · So if I run a single producer, and 2 consumer processes (consumers run from command line like Consumer. KafkaListenerEndpointContainer#0-0-C-1 So, with a unique instance of the application, one thread is reading the 50 partitions. Using these 2 approaches, by default, the Consumer tries to consume from all partitions fairly. In this tutorial, we’ll explore how the Kafka Consumer retrieves messages from the broker. 0. edit: this also means you can get messages out of order if your single topic Consumer switches partitions for some reason. This client also interacts with the broker to allow groups of consumers Jun 16, 2017 · The way consumption is implemented in Kafka is by dividing up the partitions in the log over the consumer instances so that each instance is the exclusive consumer of a "fair share" of partitions at any point in time. May 21, 2023 · In general, Kafka offsets are auto-committed once the consumer gets the messages. This means that if there is a backlog of messages in the queue, it will take longer to process them all. Mar 20, 2023 · Quarkus provided configuration where you can have 1 consumer run with multi-threaded way, its useful when there a Kafka cluster with high partitions and replications, 1 app can concurrently consume lots of messages in Async way. What do you mean by "great to the number of consumers". Consumers poll brokers periodically using the . The second step is to Dec 12, 2021 · You need to use the Kafka Parallel Consumer library. This client also interacts with the broker to allow groups of consumers to load balance consumption using consumer Each line represents input data for the Confluent Parallel Consumer application. Apr 29, 2024 · A multiprocess multithreaded Kafka consumer. Let´s say you have 10 partitions for your topic, then you can have 10 consumers in the same consumer group reading one partition each. public class KafkaConsumer<K,V>. If you have 20 partitions and 4 threads; they'll get 5 partitions each. Please confirm my understanding. Kafka Streams also provides real-time stream processing on top of the Kafka Consumer client. out. Process. The kstreams config num. ack. Assume you have multiple data files. Once the data has been delivered that thread, the thread may deliver the messages to multiple pool of threads to allow them to process in parallel. exe "cg2". This topic provides Apache Kafka® consumer configuration parameters. Consumers are single threaded. If the concurrency is two, and the partitions on each topic > 1, each consumer will get some partitions from each topic. Start a thread pool with max_workers equivalent to the number of partitions your topic has. Jan 8, 2024 · In this article, we’ll learn how to configure multiple listeners for the same Kafka topic by looking at a practical example. return c. When a new process is started with the same Consumer Group name, Kafka will add that processes' threads to the set of threads available to consume the Topic and trigger a 're-balance'. * @return the topic names or expressions (SpEL Dec 3, 2022 · 10. concurrency=2. * The entries can be 'topic name', 'property-placeholder keys' or 'expressions'. If the concurrency is 1, all topics, all partitions will be processed on a single consumer. interval. Same if you have N partitions with N + 1 or 2 or 3 instances of your application. bindings. For information about supported versions, see Supported Systems and Versions. Feb 7, 2019 · These are used by the brokers to respectively determine how much data to return in total and per partition. 0 and Windows. Also i will configure each consumer in a different consumer-group. That way you can spin up as many instances as you need to get optimal partitioning. So, multiple servers may be used to house the instances to Apr 1, 2020 · No. threads to configure the number of threads. threads",4); Nov 3, 2023 · Multi-threaded Kafka Consumer. If one consumer runs multiple threads, then two messages on the same partitions could be processed by two different threads which make it hard to guarantee Jan 7, 2024 · Overview. Aug 2, 2018 · public void sendPost(ConsumerRecord<String, Post> consumerRecord, Acknowledgment ack) {. So in Kafka case, the number of partitions is your parallellism. InstanceAlreadyExistsException: kafka. 0. I am working on a spark streaming application using spark structured streaming, confluent open source Kafka cluster and running spark job in AWS EMR. 11. poll(Duration. STDOUT. MILLIS)); records. ” Imagine you have multiple producers publishing to a kafka topic. One instance will process your data, the other will wait and start processing messages in case the first instance crashes. acknowledge(); } If I understood correctly, right now I have one the single instance of my consumer. Introduction. spring. Most use cases will not require you to use threads. It helps to increase the parallelism of the application instance. We’ll be focusing on setting up a KafkaConsumer without relying on Spring Boot modules. Finally, we’ll explore how adjusting these settings affects the Consumer ‘s behavior. Instantiate a Kafka Producer. But is there additionally a way that I can keep from ever getting a batch with messages from multiple partitions, even if a rebalance does occur? – in the case of consumer1 4 consumer thread will be created and they will listen to topic1 and topic2. Feb 3, 2022 · The way Kafka is architectured, it naturally forces you to scale horizontally by adding more consumers in a group. Project Setup. This is equally applied to all partitions. g. The origin can use multiple threads to enable parallel processing of data. The configuration parameters are organized by order of importance, ranked from high to low. Yes, KafkaProducer is threadsafe. com/ravidream/kafka-consumer-with-multiple-threadsCREATE TOPIC----- Sep 21, 2022 · The one and only way to raise the interrupt flag is to write it that way: By invoking the interrupt() method on a given thread object. Multi-threaded Processing. It's possible to 'simulate' parallel consumption with the normal consumar (by having multiple consumers), but you have to hand roll a good amount of code. Though, you would have ordered storage, but the consumption would be un-ordered. Lets assume, only tpic1 exists and it has 4 partitions, then yes 4 consumer threads will listen to 4 partitions concurrently. If two . We strongly recommend a single instance of these APIs to be used at a given time. 3) Code : First the declaration of a Kafka consumer Class To optimize resource utilization, consumers can dequeue messages in one thread and then use multiple threads to process them in parallel. 1 Model #1. Jul 4, 2019 · It basically creates one consumer: c, err := sarama. Will it schedule itself between partitions ? The fetcher batches by topic partitions. If you have multiple consumers on the same partition, it beats your initial requirement of maintaining ordering. Partitions(*topic) } Then for each partition it creates a PartitionConsumer and consumes Nov 7, 2021 · In java, we can retrieve multiple records using Poll method and can get records of each partition. Create one independent thread to process each data file. 1. When you subscribe to multiple topics with a single Consumer, that Consumer is assigned a topic/partition pair for each requested topic. I am trying to pause/resume the Kafka container. Whenever a consumer consumes a message,its offset is commited with zookeeper to keep a future track to process each message only once. # release resources properly. // do some logic. I need to produce a lot of messages in Kafka as efficient as possible. With a given consumer group name, you are currently launching single consumer to read from the topic This single consumer will read from all partitions. And there are multiple such partitions within this topic. Once the messages are read, they are delivered to a threadpool for further processing. Mar 17, 2023 · https://github. Run the example. Dec 25, 2018 · It depends on Group ID. fetch. If you have 4 Kafka consumers with the same Group Id, each of them will all read three different partitions etc. Feb 5, 2017 · 1 Answer. # Commit manually to care for abrupt shutdown. These workers can run in parallel, each processing messages independently. sleep so that messages in the batch are not processed. However, the reactor-kafka documentation mentions KafkaReceiver is not thread-safe since the underlying KafkaConsumer cannot be accessed concurrently by multiple threads. Model #1. Check the library here , and this blog post . It's myThread. Jun 26, 2019 · 15k 5 40 46. If there are more than 4 partitions then some thread will switch between 2 or more partitions. May 11, 2022 · How to use multi-thread consumer in kafka 0. I will The standard consumer interface serves messages from one topic+partition (toppar) with one call to rd_kafka_consume*(). In situations where the work can be divided into smaller units, which Apr 25, 2016 · The Consumer Group name is global across a Kafka cluster, so you should be careful that any 'old' logic Consumers be shutdown before starting new code. getListenerContainer("MAIN"). start(); where the new thread starts execution. To send all of the events below, paste the following into the prompt and press enter: fun-line:All streams lead to Kafka event-promo:Go to Current event-promo:Go to Kafka Summit fun-line:Consume gently down the stream. As long as all consumers use the same group. Jan 15, 2021 · Consumer with many threads: If processing a record takes a while, a single Consumer can run multiple threads to process records, but it is harder to manage offset for each Thread/Task. However, it may be preferable to simply run multiple instances of your streaming app, with all of them running the same consumer group. Aug 3, 2020 at 18:19. bytes usually helps. A quick lesson for advanced users on running Kafka Consumers in a separate thread. hz tq np fx id jn id jw bw sk