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Comment by strken | Hacker News Reader

I'm doing some work on a friend's startup, and we have a pretty stark divide between our hot path gateway service and our lower traffic services.

All three of our services are currently written in typescript with no plans to change, but I've earmarked the gateway as "maybe we'll rewrite it in Rust in three years." It's so small it's nearly trivial (so a rewrite of that specific service will be quickish) and infrequently changed (so hiring won't be as big an issue), it deals with low latency IO-heavy workloads (so we'll possibly want a language without GC pauses), and we really don't want it to break (so it's worth more effort per line).

Not sure how a hybrid approach will work.

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FYI: If you're primarily IO-heavy, the GC pauses aren't going to be a big deal. Something like NodeJS (or Async .Net) will have great performance; even with garbage collection. (IO-heavy is the specific use case that NodeJS was designed to handle.)

GC pauses really become a problem when you have long-lived objects in RAM. A generational GC (which pretty much all of them are) is designed to collect short-lived objects extremely fast.

Rust definitely has its use; but in the case of a startup making an IO-heavy product, you're going to be better off spending your precious resources on a slightly faster computer instead of struggling with Rust's learning curve.

> FYI: If you're primarily IO-heavy, the GC pauses aren't going to be a big deal. Something like NodeJS (or Async .Net) will have great performance; even with garbage collection. (IO-heavy is the specific use case that NodeJS was designed to handle.)

This just isn't true. Node is pretty terrible even at IO heavy workloads, especially if you have servers with many cores. Any benchmark will confirm this.

Their point is that GC is fine. Your're focusing on one of the suggestions: nodejs.

But .NET or Go are very fast for typical I/O bound workloads.

Yes, that's why I quoted one specific part and responded to that specific part.

No you included the GC part too:

> FYI: If you're primarily IO-heavy, the GC pauses aren't going to be a big deal.

To further my point: .NET and Java are amazing when it comes to performance for most cases. You get a mature ecosystem, large developer pool, fast runtime and all the comfort that GC offers.

I'd argue that choosing Rust for most startups is outright irresponsible.

Yeah fair, in my mind I was just responding to the bit about node, but whatever.

> I'd argue that choosing Rust for most startups is outright irresponsible.

I feel the opposite and I run a startup using Rust. If I could go back I'd use Rust in more places, not fewer.

Rust, Python and Go. Props to you for being sensible with technology choice.

https://github.com/grapl-security/grapl

https://github.com/grapl-security/pulumi-hcp

Whish you guys success.

Much appreciated

Is not Java or Go but surely beats the pants out of Ruby/Python, and then, Ruby/Python has been wildly successful for lots apps/companies.

Of course. It's also better than solving problems with pen and paper.

Not to be a pain but Node has its place in distributed, single-core servers

This is sort of highlighted by other comments, but GC is only good at small quick requests. If you're dealing with large or slow requests it results in large or long lived allocations which causes havoc with GC. This is true for any generational GC, Java included.

Also node will only perform well if that IO is offloaded to the kernel or CPP code and behind a future via epoll etc... If it's in the actual node runtime it'll perform poorly because it'll block the thread.

I don't necessarily agree. Depending on what kind of IO they're doing, the latency and consistency of latency from a rust service can be so much better while requiring so much less in terms of computing resources that it actually sets their business apart, attracting customers based on quality or saving them enough money on infra bills to hire more salespeople. It can be a big difference in performance. I have done comparisons across rust, node, java, c# and strongly believe rust is worth it for performance-criticial code, and rust is subjectively very enjoyable to write, for me. I really want a job doing it and so admittedly the "it's too hard" attitude is a thorn in my side.

Are there any good books that talk about this? When when to use what, what the bottlenecks are and how they are resolved? Maybe on a more abstract plane than if IO-heavy use NodeJS, more like what to look for?

> Not sure how a hybrid approach will work.

The hybrid approach works great. We use typed scripting languages for business logic and Rust CLI tools for "inner loops", and this balance gives us the best of both worlds.

There is an important caveat here: If you are already comfortable in Rust, then it's a fantastic tool for all sorts of things. But if you're just learning Rust, then there's a one-time cost for getting comfortable. So for a small team with zero prior Rust experience, expect to spend 2-6 weeks getting comfortable. (The learning curve is shorter if you already know about pointers and closures, and longer if it's your first low-level language.)

Your plan sounds entirely reasonable.

2-6 weeks? I wish I could learn Rust in that time.

> The learning curve is shorter if you already know about pointers and closures

Every time I read something like this, I'm reminded that pointers and closures aren't universally understood concepts in professional programmers. And I'm sad.

I share this sentiment, it's kind of a bummer. I ran into this non-stop in enterprise Java/C# development environments, more specifically in developers who are not "classically schooled" (i.e. bootcampers). Fact of the matter was, they never needed to know about pointers to do their job. They only even knew the term from the "null pointer exception". I looked into the curriculum of various levels of IT studies and unless you get taught at university level there are little to no memory / hardware oriented classes. It has started to get a bit better since the introduction of Java 8 (don't look up how long ago this was, ouch) and people got familiar with "lambda's".

The 2-6 weeks figure seems optimistic to me. I think it’s easy to underestimate how long it takes to switch languages and operate at a high level of productivity in the new language. Yes, switching languages is much easier than learning to program. Yes, I would rather hire a proficient programmer who doesn’t know the language than a mediocre programmer who does. But no, I don’t think that 6 weeks is enough for most people to get their Rust skills to a professional level.

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