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Comment by toast0 | Hacker News Reader

TCP has some real issues, MTU discovery is either slow or not enabled or not very smart on a lot of clients. Google, for some reason, doesn't want to fix tcp in Android, instead they went with implementing tcp inside of tcp (http/2), and since that ran into the obvious problems, they've realized that tcp over UDP is a better choice. As far as I can tell, they still haven't enabled TCP MTU discovery in Android though. Or build apis to allow applications to influence packetization and congestion control -- which is what is probably needed. The java apis for TCP are fairly inflexible too, to set most socket options you have to call into c code, and hunt around to get the FD.

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h2 is not tcp on tcp.

h2 failed because it's mux everything into 1 single tcp connection, and it only takes 1 failed tcp to block everything in line.

h2 really need to do demux. But h2 actually can technically do M:N connections, but browsers do only 1:N.

Also h2 is a failed promise. Most sites deliver web assets and page and js in different host, also ws/wss in a different host. Thus renders h2 advantages complete useless.

> “h2 failed”

Just curious, what do you mean? Quickly Googling this, it looks like 1/3 websites use HTTP2 today, which is darn good for a relatively new protocol.

https://w3techs.com/technologies/details/ce-http2/all/all

Can't always correlate usage share with performance, especially on things that are extremely hyped.

Googlebot never adopted HTTP2, only SPDY

By failed I mean h2 did not fulfill its design goal and technical potential.

Most sites use h2 by just wrapping http/1.0 behind some h2-enabled CDN or upgrade to latest nginx and call it done.

What about h2 push? Priority? WS inside h2? Nope. No one use them obviously.

I mean gRPC utilized more h2 features than most h2 browsers/CDN do.

I mean, it’s just the beginning right? You’re making it sound like it’s the end of the road for HTTP2.

I used push with the help of Caddy. Pretty easy.

I'm curious to hear what you mean by WS inside h2, not sure how that's different. WS is only http for the first part i.e. the upgrade request.

Jetty/CometD has decent support. You can use HTTP2 as a transport for push notifications. You can also specify additional resources like scripts, css, or images to be sent on the first request.

I am less worried about what most sites do and more interested in the features offered by implementations. A huge number of sites don't even use https.

The idea is good, but static assets and dynamic content (APIs, pages, etc) have different scaling models. I don't think mix them in a single transport layer have much real world usage.

That doesn't sound like failure to me. Newer generations of standards and protocols have features that won't be used by everyone. The goal is not maximum feature adoption, the goal is to reduce latency. There's a tradeoff between implementation complexity and benefit that changes as you incorporate additional h2 features into your web site. At some point you decide the additional features do not provide enough benefit to support the additional implementation complexity. This is normal and expected, and I'm surprised that someone would interpret this as a failure of h2.

Again, the goal of h2 is not to maximize usage of features in the h2 protocol. So judging h2 by that metric does not make any sense. I could just as easily complain that HTTP is a failure because few sites use more than just GET/POST, or because many of the headers defined in the HTTP standard are not commonly used.

How is multiplexed streams with individual windows on each substream not tcp on tcp?

Sure, there's some other stuff in there, server sent goaway in particular is a great way to indicate the server intentionally closed the connection, but the primary objective is to get around congestion control -- which could have been better solved by just adjusting congestion control to pool by destination IP in clients Google could control (at least Android) and on servers Google could control (at least their servers)

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