Why Discord is switching from Go to Rust

The Go's GC is groundbreaking in several aspects, but probably needs to provide ways to fine-tune it. Posts like this make me believe that one-size-fits-all settings are yet to be seen.

[0]: https://blog.twitch.tv/en/2019/04/10/go-memory-ballast-how-i...

First and foremost, we do care deeply about desktop performance. We shipped this week a complete rewrite of our messages components, that come with a boatload of performance optimizations, in addition to a new design. We spent a lot of time to do that rewrite in addition to applying new styles, because given what we know now (and what's state of the art in React world), we can write the code better than we did 3+ years ago. In terms of total engineering time spent, the rewrite of messages actually took much longer than the rewrite of this service from go to rust.

That being said, the desktop app does load much slower than we'd like (and honestly than I'd like personally.) I commented in another thread why that is. That being said, the person who is writing backend data-services, is not the one who's going to be fixing the slow boot times (our native platform team). These are efforts that happen independently.

As for our motivations for using rust, I think saying that "a little GC jitter on the server requiring a complete rewrite" is one of many reasons we wanted to give rust a shot. We have some code that we know works in a Golang. We want to investigate the viability of Rust to figure out how it'd look like to write a data service in rust. We have this service that is rather trivial, and has some GC jitters (that we've been fine with for a year.) So, an engineer (the author of this blog post) spends some time last year to see what it'd look like to write an equivalent service in rust, how it'd perform, how easy it'd be, and what the general state of the ecosystem is like in practice.

I think it's easy to forget that a lot of work we do as engineers isn't all about what's 100% practical, but also about learning new things in order to explore new viable technologies. In this case, this project had a very clear scope and set of requirements (literally rewrite this thing that we know works), and a very well defined set of success criteria (should perform as-good or better, see if a lack of GC will improve latencies, get a working understanding of the state of the ecosystem and how difficult it would be to write future data services in rust vs go.) Given the findings in our rewrite of this service, running it in production, and now using features that have stabilized in rust, we're confident in saying that "in places where we would have used golang, we consider rust viable, and here's why, given our exercise in rewriting something from go to rust."

Rust has a much nicer standard library, and the semantics and abstractions are so incredibly beautiful. It's a language that has learned from the millions of human-years that went into other languages and ecosystems. Every corner and seam in the language design speaks to this.

Traits, union type enums, pattern matching, option and result types, derive(), error handling semantics - it's all incredibly intuitive and expressive.

If I had a choice to write Rust everywhere, I would.

> The common factor in most of my decisions to look for a new job has been realizing that I feel like a very highly compensated janitor instead of a developer.

So for that person, feeling like a janitor is incentive for seeking a new job. It's that simple really.

In that case, Go is Bell Labs' second attempt at Java.