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Learn about request purgatories, Kafka client mechanics, and Flink!

July 27, 2023

Vacuuming out your car? Folding your laundry? We’ve got an audio recommendation for you! This week, listen to (or watch!) Danica Fine’s talk on how client requests work. If you want to get nerdy with us, we’ve also got a blog post on timing wheels and how those support request purgatories. Also, consumer groups are getting a shiny new protocol… learn why!

Apache Kafka® Resources:

  • Consumer groups are getting a new protocol! Stanislav Kozlovski summarizes the update in a LinkedIn post.
  • Let’s track a Kafka client request’s journey to disk and back! View Danica Fine’s enlightening talk on client internals.
  • Speaking of client internals… ever heard of a request purgatory? No, we’re not talking about Dante’s Inferno… it’s a special data structure designed to keep track of asynchronous requests, and you can read more about it in a classic blog post, or get academic with timing wheels (which are what make a request purgatory tick).
  • If you missed it, catch up on the new features in Apache Kafka 3.5 with this succinct summary.

Apache Flink® Resources:

Terminal Tip of the Week:

Today we have a couple of quick usability tips for kcat.

Sometimes, when you're running kcat, you don't want it to be open in the background… you just want to run a command and read the result. In that case, you can add an -e flag to exit, in this case, after printing the last 300 lines from partition 2:

$ kcat -C -b broker_name -t topic_name -p 2 -o -300 -e

You can also view messages in JSON with a -J flag:

$ kcat -b broker_name -t topic_name -J

Links From Around the Web:

In Other News:

  • Join us for an in-person Kafka meetup in Melbourne on July 27! Learn from Confluent engineer Warren Vella—he’ll give a talk on how to integrate operational and analytical systems with Kafka.
  • Registration is now open for Current 2023, in San Jose, Sep 26-27! Network with data streaming experts from across the globe and learn new approaches to using Kafka in the breakout sessions.

By the way…

We hope you enjoyed our curated assortment of resources! If you’d like to provide feedback, suggest ideas for content you’d like to see, or you want to submit your own resource for consideration, send us an email at!

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P.S. If you want to learn more about Kafka or Confluent Cloud, visit our developer site at Confluent Developer.

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