No, this will not make routing issues worse.

The routing issues described in that post specifically apply to single-threaded / non-concurrent applications (or those with very low concurrency, such as Unicorn w/ 2 workers).

WebSocket connections are like requests that last forever. If you're using WebSockets in your app, you'll need your app to be highly concurrent in order to maintain lots of open connections to your users. You don't want regular requests to block behind never-ending WebSocket requests.

Random routing should actually work pretty well on apps with high concurrency. Node.js, Play, Go, Erlang, and even Ruby apps with Faye should all work great.

If you're concerned about this for your app, the best way to find out is to test it!

Note to readers: the only thing that "fixes" this is if the request-handling code is asynchronous in such a way that it doesn't block a process when connections are held idle. Most of the common web frameworks don't do this because the coding required to make a fully asynchronous stack is nasty. Even apps written in nominally asynchronous frameworks (like node.js) could be in trouble if the request path is pathological (i.e. the websocket periodically makes long-running, blocking database queries).

That said, most of you will never encounter this problem, because it's the sort of problem that's "nice to have" -- by the time concurrency issues become a limit, your app will be popular.

It's safe to assume that anyone who hopes to leverage websockets will not be using a blocking application architecture.

We can also assume people are running this software on multiprocessing machines with connections to the internet.

Of course there's always people "doing it wrong," but caveating every potential misunderstanding is a slow way to communicate.

edit: Your post is still valuable though! Thanks for highlighting what makes these frameworks sensible for use with websockets.

No, it isn't. I'll wager that right this very second, there's someone out there incorporating websockets into their Heroku-based Rails app and not thinking about (or understanding) the consequences.

Heroku's past routing problems with certain low concurrency frameworks/servers doesn't apply with WebSockets because you'd be crazy to use such a framework for WebSockets.

Rails only supports one concurrent connection per process (by default...for good reasons), and there are a great many people using it at scale, including on Heroku. Asynchronous stacks are becoming more common, but they're still exotic in terms of deployment -- and most of those probably aren't written very well.

And I think lots of people would disagree that async stacks are still "exotic" or "not written very well".

Yes, no kidding. But people will still try to do this with frameworks that don't support anything else (like Rails), because that's the shortest path to a working product.

"And I think lots of people would disagree that async stacks are still "exotic" or "not written very well"."

Well, those "lots of people" can disagree all they want, but they're wrong. The problem isn't that the frameworks are badly written, necessarily -- it's all the stuff in the stack, including the app-specific logic. Virtually no one knows how to write asynchronous web apps of any complexity. It's a very hard problem.

It's nice that you guys are adding this stuff, but it doesn't invalidate the larger point.