WhyKafkaSoFast.md

Why Kafka is so fast?

• Kafka achieves low latency message delivery through Sequential I/O and Zero Copy Principle.
• Messages (events) in the Kafka are immutable and can't be changed once it's pushed (due to log based queue nature).
• The same techniques are commonly used in much other messaging/streaming platforms.

Kafka is based on Log Based Queue

• ⭐ Messages are persisted to append-only log files by the broker.
• Producers are appending these log files (sequential write) & consumers are reading a range of these files (sequential reads).

Why reading from Kafka is so fast?

• Reading data out of Kafka is very fast thanks to java.nio.channels.FileChannel#transferTo.
• This method uses sendFile system call which allows for very efficient transfer of data from a file to another file (including sockets).