this post was submitted on 15 Jun 2023
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Programming

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My first experience with Lemmy was thinking that the UI was beautiful, and lemmy.ml (the first instance I looked at) was asking people not to join because they already had 1500 users and were struggling to scale.

1500 users just doesn't seem like much, it seems like the type of load you could handle with a Raspberry Pi in a dusty corner.

Are the Lemmy servers struggling to scale because of the federation process / protocols?

Maybe I underestimate how much compute goes into hosting user generated content? Users generate very little text, but uploading pictures takes more space. Users are generating millions of bytes of content and it's overloading computers that can handle billions of bytes with ease, what happened? Am I missing something here?

Or maybe the code is just inefficient?

Which brings me to the title's question: Does Lemmy benefit from using Rust? None of the problems I can imagine are related to code execution speed.

If the federation process and protocols are inefficient, then everything is being built on sand. Popular protocols are hard to change. How often does the HTTP protocol change? Never. The language used for the code doesn't matter in this case.

If the code is just inefficient, well, inefficient Rust is probably slower than efficient Python or JavaScript. Could the complexity of Rust have pushed the devs towards a simpler but less efficient solution that ends up being slower than garbage collected languages? I'm sure this has happened before, but I don't know anything about the Lemmy code.

Or, again, maybe I'm just underestimating the amount of compute required to support 1500 users sharing a little bit of text and a few images?

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[–] [email protected] 12 points 1 year ago (9 children)

"GC overhead" only matter for extreme realtime applications, like emulators, games, drivers, simulators, etc. a 10msec (or even a 100msec) pause in a request processing isn't gonna even be noticed when your network, database and disk IO are literally orders of magnitude higher. Use Rust for web services if you like the language, comfortable with it, etc. Don't use it because you think it'll give you "more performance" or "reduce GC overhead".

Java, C#, Python, Node, or even PHP as languages will never be your web backend bottleneck. Large scale web services performance tuning is entirely architectural. What caches you keep, how you organize your data, how many network operation does 1 user interaction translate to, stateful vs stateless components etc.

[–] [email protected] 2 points 1 year ago (6 children)

+1, exactly this.

As an aside, "stop the world" GC pauses can affect web server performance in interesting ways. Some web application servers have a perf profile where throughput drops off a cliff as the server approaches max memory load. This is fine, so long as you know what's happening, and can tune your auto scaling to spin up new servers before you start to hit that threshold. This likely wouldn't be a reason to not use a particular lang / server, except at the most massive scales.

[–] [email protected] 1 points 1 year ago (1 children)

This is a test message. Lemmy isn't making me do the posts I want right now... does this one work?

[–] [email protected] 2 points 1 year ago
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