https://tushar-c23.github.io/tags/distributed-systems/Recent content in Distributed-Systems on Tushar ChoudharyHugoen-usSun, 20 Sep 2026 19:30:00 +0530https://tushar-c23.github.io/posts/kafka/batch-is-the-unit/Sun, 20 Sep 2026 19:30:00 +0530https://tushar-c23.github.io/posts/kafka/batch-is-the-unit/<p><em>First in the <a href="https://tushar-c23.github.io/posts/kafka/">Kafka Internals</a> series: reading the design doc against the actual source (Kafka trunk, 4.5.0-SNAPSHOT, KRaft-only). Every number below came off a single-node broker running on my laptop, and you can reproduce all of them.</em></p> <p>Kafka&rsquo;s API is message-shaped. You call <code>producer.send(record)</code> with one record. You call <code>consumer.poll()</code> and iterate <code>ConsumerRecord</code>s one at a time. The docs say &ldquo;message&rdquo; everywhere. So the obvious mental model is: a message goes in, a message sits on disk, a message comes out.</p>