Charlie Marsh: uv: An Extremely Fast Python Package Manager

What people said

kolja005 · 2024-11 · Strong recommendation

I recently watched a talk by the author of uv that was surprisingly fascinating [1]. He goes into a few of the more notable hacks that they had to come up with to make it as fast as it is. The most interesting thing for me was that package resolution in python given constraints defined (eg. in requirements.txt) maps to a boolean satisfiability problem which is NP-complete. So uv uses a custom SAT solver to do this. I totally under-appreciated how much goes into this software and I'm bummed I have to use Poetry at work after having watched this talk. [1] [VIDEO] edit: NP-complete not NP-hard

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krick · 2025-12 · Recommendation

To be fair, the whole post isn't very good IMO, regardless of ChatGPT involvement, and it's weird how some people seem to treat it like some kind of revelation. I mean, of course it wasn't specifically Rust that made it fast, it's really a banal statement: you need only very moderate serious programming experience to know, that rewriting legacy system from scratch can make it faster even if you rewrite it in a "slower" language. There have been C++ systems that became faster when rewritten in Python, for god's sake. That's what makes system a "legacy" system: it does a ton of things and nobody really knows what it does anymore. But when listing things that made uv faster it really mentions some silly things, among others. Like, it doesn't parse pip.conf. Right, sure, the secret of uv's speed lies in not-parsing other package manager's config files. Great. So all in all, yes, no doubt that hundreds of little things contributed into making uv faster, but listing a few dozens of them (surely a non-exhaustive lists) doesn't really enable you to make any conclusions about the relative importance of different improvements whatsoever. I suppose the mentioned talk[0] (even though it's more than a year old now) would serve as a better technical report. [0] [VIDEO]

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globular-toast · 2025-06 · Recommendation

There is a talk about it from one of the authors here: [VIDEO] tl;dw Rust, a fast SAT solver, micro-optimisation of key components, caching, and hardlinks/CoW.

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