http - 为什么kafka不用http？

Question

根据documention -

Kafka uses a binary protocol over TCP

Some people have asked why we don't use HTTP. There are a number of reasons, the best is that client implementors can make use of some of the more advanced TCP features--the ability to multiplex requests, the ability to simultaneously poll many connections, etc. We have also found HTTP libraries in many languages to be surprisingly shabby.

是否有任何明确的理由因为这看起来没有说服力？

Answer 1

Kafka 强调性能。

通常 HTTP over TCP 带来的开销并不大，只要您将 header 保持在最小大小即可。

但是如果您有大量的小消息来回传输，则应考虑 HTTP 的开销。

您的消息越小，开销所占的比例就越大。

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此外，基于文本的 HTTP 协议(protocol)还有很多特点。解析 HTTP 请求可能很复杂，因此比优化的二进制协议(protocol)慢。

(例如，即使是最简单的 libmicrohttpd 也很复杂。)