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Comment by troad | Hacker News Reader

> Performance of what, exactly? Hard to beat the concurrency model and performance under load of elixir.

The performance of my crummy web apps. My understanding is that even something like ASP.NET or Spring is significantly more performant than either Rails or Phoenix, but I'd be very happy to be corrected if this isn't the case.

I appreciate the BEAM and its actor model are well adapted to be resilient under load, which is awesome. But if that load is substantially greater than it would be with an alternative stack, that seems like it mitigates the concurrency advantage. I genuinely don't know, though, which is why I'm asking.

> Elixir is gaining set theoretic type system, so you are showing up at the right time. https://hexdocs.pm/elixir/main/gradual-set-theoretic-types.h...

Neat! Seems clever. Looks like it's very early days, though.

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Some of the big performance wins don’t come from the raw compute speed of Erlang/Elixir.

Phoenix has significantly faster templates than Rails by compiling templates and leveraging Erlang's IO Lists. So you will basically never think about caching a template in Phoenix.

Most of the Phoenix “magic” is just code/configuration in your app and gets resolved at compile time, unlike Rails with layers and layers of objects to resolve at every call.

Generally Phoenix requires way less RAM than Rails and can serve like orders of magnitude more users on the same hardware compared to rails.

The core Elixir and Phoenix libraries are polished and quite good, but the ecosystem overall is pretty far behind Rails in terms of maturity. It’s manageable but you’ll end up doing more things yourself. For things like API wrappers that can actually be an advantage but others it’s just annoying.

ASP.NET and Springboot seem to only have theoretical performance, I’m not sure I’ve ever seen it in practice. Rust and Go are better contenders IMO.

My general experience is Phoenix is way faster than Rails and most similar backends and has good to great developer experience. (But not quite excellent yet)

Go might be another option worth considering if you’re open to Java and C#

Thank you, I really, really appreciate the thoughtful answer.

I've written APIs in Rust, they were performant but the dev experience is needlessly painful, even after years of experience using the language. I'm now using Rails for a major user-facing project, and while the dev experience is all sunshine and flowers, I can't shake the feeling that every line I write is instant tech debt. Refactoring the simplest Rails-favoured Ruby code is a thousand times more painful than refactoring even the most sophisticated system in Rust. I yearn for some kind of sensible mid-point.

Elixir seems extremely neat, but I've been blocked from seriously exploring it by (a) a sense that it may not be more any more performant than Ruby, so why give up the convenience of the latter, and (b) not having seen any obvious improvement on Ruby's hostility to gradual typing / overuse of runtime metaprogramming, which is by far my biggest pain point. I'm chuffed to hear that the performance is indeed better, that the magic in Phoenix happens at compile time, and that gradual types are being taken seriously by the language leadership.

I guess I'll have to take Phoenix for a spin.

There's three reasons to choose elixir or perhaps any technology

The community and it's values, because you enjoy it, because the technology fits your use case. Most web apps fit. 1 and 2 are personal and I'd take a 25% pay cut to not spend my days in ASP or Spring, no offense to those who enjoy it.

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