TLDR: They use many good industry practices: - Append-only log with sequential IO - Record batching on client and broker side (works well with sequential IO)

TLDR: They use many good industry practices: - Append-only log with sequential IO - Record batching on client and broker side (works well with sequential IO) - Batch compression (Json and other text formats could be compressed very well) - Unflushed buffered writes - Zero-copy approach for working with data In addition to that the architecture of the Kafka also plays a major role so that the clients don't require much overhead. The code is written to not to put much pressure on GC and a number of other more specific optimizations was implemented on both client and server sides. The most interesting part for me was how they achieve zero-copy when working with sockets. That whole section is worth reading and they could have made another blog post about only that. Edit: formatting