How to Successfully Consume the Last Message in an Apache Kafka Topic Using Python

Learn how to resolve issues with consuming the last message in Apache Kafka using Python, including key steps and a brief explanation of the essential approach.
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How to Successfully Consume the Last Message in an Apache Kafka Topic Using Python

Apache Kafka is a powerful messaging framework widely used for real-time data streaming. However, many developers encounter challenges when trying to consume the last message in a Kafka topic, particularly when using Python. If you find yourself staring at an empty array after attempting to consume the latest message, you're certainly not alone. In this post, we will break down the issue and provide you with a straightforward solution.

The Problem: Consuming the Last Message in Kafka

You may be using the KafkaConsumer class from the kafka-python library and facing an issue where your code returns an empty list (or array) when trying to fetch the latest message from your specified Kafka topic. Here is the sample code that many users might start with:

[[See Video to Reveal this Text or Code Snippet]]

Why Is It Not Working?

The crux of the issue lies in the way the Kafka consumer is set up to read messages. When you use seek_to_end(), you are moving the cursor to the end of the queue. Therefore, you are not able to consume any messages as the current position points to the end, which doesn't yield a valid message.

The Solution: Adjusting the Offset

To effectively consume the last message from a Kafka topic, you need to adjust your offset before fetching messages. Specifically, you must move the consumer's position back by one or two offsets, depending on your use case. Here's how to do it:

Key Steps for Fetching the Last Message

Seek to the Correct Offset: Move the offset back by one position:

[[See Video to Reveal this Text or Code Snippet]]

Alternatively, you might want to use -2, since the position method returns the next record to consume.

Consume the Message: Now that you have adjusted the offset correctly, you can proceed to consume the message by polling again.

Updated Code Snippet

Here’s how your updated code could look:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By correctly navigating the offsets in your Kafka topic, you can effectively access the last message. Navigating the Kafka system can be tricky for newcomers, but with this guide, you should now have a clearer path to solving issues related to consuming the most recent messages.

If you run into any more queries or challenges, feel free to reach out or comment below!