I think an interesting take away from the study is the following.
Nothing new there, right? But when switching a site like that over to HTTP/2 the performance gain will be capped at a certain percentage no matter how large latency you have to the site because what limits such a site to perform well is the time it takes to get to the end of the slowest “dependency chain”. It is less of an issue with HTTP/1.1 since if the resources are from the same site, browsers won’t do more than 6 requests in parallel anyway (on the 6 separate TCP connections it’ll use).
It becomes evident that in order to make such a site really benefit from HTTP/2, the site would have to be modified ever so slightly so that it would deliver its contents with shorter chains and allow the browsers to get more of the resources earlier, in parallel rather than serially.
The actual talk
Splitting up a presentation in two parts with two talkers is more difficult than doing it yourself. I think we did a decent job and we ended the presentation early. It enabled us to answer to a lot of questions and we were actually quite bombarded with them – all relevant and well considered and I think we managed to bring more to the room thanks to them. A lot of the questions were about more generic HTTP/2 and deployments though and not all exactly about the performance study of the presentation.
The audience gave us an average score of 3.74 out of 5. Not too shabby. The room seated 360 persons but it wasn’t completely filled up.
I was invited speak at the GOTO Copenhagen conference that took place on October 5-6, 2015. A to me previously unknown conference that attracted over a thousand attendees in a hotel in central Copenhagen. According to the info desk, about 800 of these were from Denmark.
My talk was about HTTP/2 (again), which I guess doesn’t make any reader of this to raise his or hers eyebrows. I’d say there were about 200 persons in the audience as the room was fairly full. Probably one of the bigger audiences I’ve talked HTTP/2 to so far.
Following my talk was talks about mod_http2, the Apache module for HTTP/2 that will be coming in the upcoming 2.4.17 release of Apache Httpd, explained by its author Stefan Eissing. The name of the module was actually a bit of a surprise to me since it has been known as just mod_h2 for its entire life time up until now.
William A Rowe took us through the state of TLS for the main Apache servers and yeah, the state seem to be pretty good and they’re coming along really well. TLS and then HTTPS is important as that’s really a prerequisite for HTTP/2
I also got to listen to Mark Thomas explain the agonies of making Tomcat support HTTP/2, and then perhaps especially how ALPN and a good set of ciphers are hard to get in Java.
Jean-Frederic Clere then explained how to activate HTTP/2 on all the Apache servers (tomcat, httpd and traffic server) and a little about their HTTP/2 state, following with an explanation how they worked on tomcat to make that use OpenSSL for the TLS layer (including ALPN) to avoid the deadlock of decent TLS support in Java.
All in all, a great track and splendid talks with deep technical content. Exactly the way I like it. Thanks everyone. Apachecon certainly delivered for me! Twas fun.