Kafka Consumer
- Concepts. A consumer group is a set of consumers which cooperate to consume data from some topics. ...
- Kafka Consumer Configuration. The full list of configuration settings are available in Kafka Consumer Configurations for Confluent Platform .
- Message handling. ...
- Kafka Consumer Group Command Tool. ...
- Example code. ...
- Suggested Reading
How many consumers can you have in a Kafka consumer group?
You can have at max consumers equal to the number of partitions of a topic in a consumer group, adding more consumers than the number of partitions would cause the extra consumers to remain idle, since Kafka maintains that no two partitions can be assigned to the consumer in a consumer group.
What is a consumer group?
A consumer group is a group of consumers (I guess you didn’t see this coming?) that share the same group id. When a topic is consumed by consumers in the same group, every record will be delivered to only one consumer.
What is the maximum number of consumers in a group?
All the Consumers in a group have the same group.id. Only one Consumer reads each partition in the topic. The maximum number of Consumers is equal to the number of partitions in the topic. If there are more consumers than partitions, then some of the consumers will remain idle. A Consumer can read from more than one partition.
What happens when more consumers are in the same group?
Having more consumers in the same group increases the degree of parallelism and the overall throughput of consumption. On the other hand, if each consumer is in its own group, each consumer will get a full copy of all messages.
What is the consumer group?
noun. /kənˈsjuːmə ɡruːp/ /kənˈsuːmər ɡruːp/ an organization that makes sure the goods and services people buy or use are safe and that consumers are treated fairly.
What is consumer and consumer group?
A consumer group is a group of multiple consumers which visions to an application basically. Each consumer present in a group reads data directly from the exclusive partitions. In case, the number of consumers are more than the number of partitions, some of the consumers will be in an inactive state.
Why Kafka has consumer group?
Kafka assigns the partitions of a topic to the consumer in a group, so that each partition is consumed by exactly one consumer in the group. Kafka guarantees that a message is only ever read by a single consumer in the group. Consumers can see the message in the order they were stored in the log.
Is consumer group mandatory in Kafka?
The consumer group-id is mandatory, it plays a major role when it comes to scalable message consumption. To start a consumer group-id is mandatory.
What are 4 types of consumers?
There are four types of consumers: omnivores, carnivores, herbivores and decomposers. Herbivores are living things that only eat plants to get the food and energy they need.
How many consumer groups can be created in Kafka?
In Kafka, there is no explicit limit on the number of consumer groups that can be instantiated for a particular topic. However, you should be aware that the more the consumer groups, the bigger the impact on network utilisation.
Can multiple consumer groups same topic?
A topic can be consumed by many consumer groups and each consumer group will have many consumers. A topic is divided into multiple partitions. A consumer in a consumer group is assigned to a partition. Only one consumer is assigned to a partition.
Can a consumer group read from multiple topics?
Multi-Topic Consumers We may have a consumer group that listens to multiple topics. If they have the same key-partitioning scheme and number of partitions across two topics, we can join data across the two topics.
How many consumers can be a part of consumer group?
one consumerA record gets delivered to only one consumer in a consumer group. Each consumer in a consumer group processes records and only one consumer in that group will get the same record. Consumers in a consumer group load balance record processing.
Is Kafka pull or push?
Since Kafka is pull-based, it implements aggressive batching of data. Kafka like many pull based systems implements a long poll (SQS, Kafka both do). A long poll keeps a connection open after a request for a period and waits for a response.
What if Kafka consumer goes down?
If the consumer goes down or is taken down for some reason, it can query the Kafka server for the last committed offset and resume message consumption as if no time has been lost. For its part, the Kafka broker stores this information in a topic called __consumer_offsets .
Can Kafka consumer listen to multiple topics?
Yes, Kafka's design allows consumers from one consumer group to consume messages from multiple topics.
What are consumer groups in marketing?
The phrase "consumer group" can actually have a couple of common uses. In marketing, it is a group of household customers with shared traits that a company targets with advertising. However, this is more often referred to as a target market or customer group.
Which are examples of customer groups?
Customer Segmentation ExamplesGender.Age.Occupation.Marital Status.Household Income.Location.Preferred Language.Transportation.More items...•
What are the 3 type of consumers?
Primary consumers, mostly herbivores, exist at the next level, and secondary and tertiary consumers, omnivores and carnivores, follow.
What is consumer group in event hub?
A consumer group is a view (state, position, or offset) of an entire event hub. Consumer groups enable multiple consuming applications to each have a separate view of the event stream, and to read the stream independently at their own pace and with their own offsets.
What is a consumer group in Kafka?
Kafka consumer group is basically several Kafka Consumers who can read data in parallel from a Kafka topic. A Kafka Consumer Group has the following properties: All the Consumers in a group have the same group.id. Only one Consumer reads each partition in the topic. The maximum number of Consumers is equal to the number of partitions in the topic.
Why is Kafka so popular?
Although it is based on the publish-subscribe model, Kafka is so popular because it has the advantages of a messaging queue system. As discussed earlier, if we have a Consumer group, Kafka ensures that each message in a topic is read-only once by a Consumer (Which is similar to a Message Queue system).
How many partitions are there in Kafka?
Let’s assume that we have a Kafka topic, and there are 4 partitions in it. Then we can have the following scenarios: 1. Number of consumers = Number of partitions. In this case, each Consumer will read data from each partition, which is the ideal case. 2.
What is load balancing in Kafka?
Load Balancing: Kafka shares the partitions fairly with each Consumer, thereby making the process of data consumption smooth and efficient.
How many consumers read each partition in a topic?
Only one Consumer reads each partition in the topic.
Why Kafka Consumer Groups?
In distributed computing frameworks, the capability to pool resources to work in collaboration isn’t new anymore, right? In other words, you may be asking “why Kafka Consumer Groups?” What makes Kafka Consumer Groups so special? Good question, thanks for asking.
What is a consumer group in Kafka?
Kafka Consumer Groups are the way to horizontally scale out event consumption from Kafka topics… with failover resiliency. “With failover resiliency” you say!? That sounds interesting. Well, hold on, let’s leave out the resiliency part for now and just focus on scaling out. We’ll come back to resiliency later.
Why do I put "workers" in quotes?
I put “workers” in quotes because the naming may be different between frameworks. But in this case, “workers” is essentially an individual process performing work in conjunction with other processes in a group or pool. Multiple processes working together to “scale out”. In Kafka Consumer Groups, this worker is called a Consumer.
Does Kafka have a Zookeeper dependency?
Like many things in Kafka’s past, Kafka Consumer Groups use to have a Zookeeper dependency. But starting in 0.9, the Zookeeper dependency was removed. So, if you are revisiting Kafka Consumer Groups from previous experience, this may be news to you. There’s a link in the Reference section below which you might want to check out if you are interested in learning more about the dependency history.
Does Kafka require a resource manager?
The coordination of Consumers in Kafka Consumer Groups does NOT require an external resource manager such as YARN. The capability is built into Kafka already. This is an attractive differentiator for horizontal scaling with Kafka Consumer Groups. Put another way, if you want to scale out with an alternative distributed cluster framework, you’re going to need to run another cluster of some kind and that may add unneeded complexity.
Can a consumer consume more than one partition?
So, to recap, it may be helpful to remember the following rules: Each partition in a topic will be consumed by exactly one Consumer in a Consumer Group. Now, one Consumer may consume from more than one partition, if there are fewer Consumers in a Consumer Group than there are topic partitions.
Should the number of consumers in a consumer group equal or less than partitions?
If you like deploying with efficient use of resources (and I highly suspect you do), then the number of consumers in a Consumer Group should equal or less than partitions, but you may also want a standby as described in this post’s accompanying screencast.
Consumer group
A consumer group in Kafka composes of one or more consumers where each consumer reads from different partitions of a topic. As each consumer reads from separate partitions, this guarantees that the message will not be duplicated.
What is a consumer group co-ordinator?
One of the Kafka brokers gets elected as a group co-ordinator. The group co-ordinator makes the group leader and group members. When a group member leaves or a new member joins the group co-ordinator initiate the rebalance of partitions to the group members.
What is a consumer group leader?
The first member joins in a consumer group becomes the consumer group leader. The group co-ordinator manages that. The consumer group leader executes rebalance activities.
What happens if a topic has 1 partition and you have 2 consumers?
If a topic has 1 partition and you have 2 consumers then 1 consumer reads from 1 partition and the other just sits there...
What is a Kafka consumer?
A Kafka consumer is technically a process that is part of a larger group. This collective group of consumers is called a "consumer group".
What is group ID?
The group.id is how you distinguish different consumer groups. Remember that consumers work together in groups to read data from a particular topic.
How many partitions can a consumer read?
If you have two consumers with different group ids, both consumers will read from 10 partitions.
Importance of Kafka Consumer Group
Advantages of Kafka Consumer Group
- If you remember when we talked about topics, we said that each record is uniquely identified by an offset in the partition. These offsets are used to track which record has been consumed by which consumer group. Kafka employs an approach of ‘a dumb pipeline, smart clients’ meaning that Kafka brokers don’t know anything about consumer offsets. The c...
Use Case Implication
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