Apache Kafka is an open-source distributed even store as well as streaming system ideally used for stream processing, data integration, and real-time data pipelines. It is developed by the Apache software foundation. It is written in Scala and Java. As it is open-source, which signifies it is free for programmers and developers. It is being used since its launch in 2011. When working with Kafka there are certain errors that you may have encountered. And beginners have many questions in mind and want the answer to their questions like How to attempt to heartbeat failed since group is rebalancing?
Before answering the question, it is really important to understand it and get to know as much as possible to solve it in a better way.
What is heartbeat?
In Kafka, we have a thread called heartbeat that sends heartbeat messages in order to keep track of the liveness of the remote coordinator as well as the consumer. The threads only work when there is stability in the group. In the case of instability, the thread gets disabled till the group becomes stable again.
Now that you know what is Kafka and its heartbeat, let’s figure out how the error pops up
How the error occurs
When you are working with Kafka, you get the following error message
2022-07-04 12:17:54,168 INFO thread=kafka-coordinator-heartbeat-thread | periodicSync o.a.k.c.c.i.AbstractCoordinator:1054 : [Consumer clientId=consumer-periodicSync-5, groupId=periodicSync] Attempt to heartbeat failed since group is rebalancing
[Consumer clientId=consumer-periodicSync-5, groupId=periodicSync] Attempt to heartbeat failed since group is rebalancingYou must get irritated as soon as the error shows up, it is normal. We tell you how to fix it in a simpler way. Let’s first check the cause of the error
Cause of the error
Kafta begins to rebalance when the group is joined by the consumer. Once the rebalancing is done, it is the responsibility of the coordinator to notice the number of consumers who joined the group and then begin another rebalancing. The process continues till the group is joined by all consumers. The error shows up when it rebalances. When a consumer is joined or left the group, it rebalances. When consumers’ instances get delayed to submit the next heartbeat for too long, then you get the error warning.
How To Solve “attempt to heartbeat failed since group is rebalancing”
To get rid of the error, you need to ensure to either pass heartbeat (heartbeat.interval.ms) more frequently or strengthen the timeout (session.timeout.ms). The poll() method is known to send a heartbeat to inform the coordinator of the group, whereas session.timeout.ms is responsible to control the time a consumer without sending a heartbeat. The main point to focus on is to set the session.timeout.ms to higher as it can minimize the chance of rebalancing and it will also take longer to identify the failure.
Conclusion
In this post, we inform you about the heartbeat and how to attempt to heartbeat failed since group is rebalancing.
I hope you find it helpful! I wish you luck!