core: disable server-side HTTP pipelining by default

[jrudolph]

It's somewhat of an obscure feature which doesn't seem to be tested well.

[akka-ci]

Test PASSed.

[ennru]

LGTM.

[raboof]

Wouldn't performance suffer because this would cause many more TCP (and perhaps TLS) handshakes in scenario's where there's a lot of small requests (and perhaps head-of-line blocking isn't such an issue)? Or am I thinking of a different 'pipelining' feature there?

[jrudolph]

It's not about persistence but about pipelining. Pipelining helps only with the latency of sending over requests because responses still need to be delivered in order.

The only place where I see it used in "practice" is in benchmarks where sending over multiple requests in one go helps with avoiding system calls.

Wouldn't performance suffer because this would cause many more TCP (and perhaps TLS) handshakes in scenario's where there's a lot of small requests (and perhaps head-of-line blocking isn't such an issue)? Or am I thinking of a different 'pipelining' feature there?

This scenario would probably benefit from pipelining but you will first have to find a client which supports it.

After all we are just following the way that curl went: https://daniel.haxx.se/blog/2019/04/06/curl-says-bye-bye-to-pipelining/

[raboof]

OK then ;)