3 ms·

There wouldn't be any surprises, or cognitive dissonance, from using very different paths for debug versus release builds? On a small project, personally I us

There wouldn't be any surprises, or cognitive dissonance, from using very different paths for debug versus release builds? On a small project, personally I use --release sometimes during development because the compile time doesn't matter that much and the resulting executable is much faster: if I don't use --release I can get a misleading sense of UX during development.

steveklabnik 7y ago
This already happens a bunch, even with the current setups. It's very natural if you come from a compiled language, and not if you don't. The first step of someone saying "hey why is Rust slow?" is five people replying "did you use --release".
- sfink 7y ago
  Can confirm. I had a graph traversal program written in Python. I ported it to Rust, and the runtime was identical -- 68.4 seconds, down to the tenth of a second. (Kinda blew my mind -- I had to triple check that I was running and timing what I thought I was!) I had a bit of a crisis of faith. I poked at it a few times over the next week, then finally got on the IRC channel and quickly received the advice mentioned above. Same input, with --release: 6.2 seconds.
Leherenn 7y ago
It's funny, because I do the exact opposite. As a developer I usually have a pretty powerful machine, and I've found that debug mode is a good way to approximate slow computers, and something that is unbearably slow in debug will bother some users later on.
- runevault 7y ago
  This is an interesting idea, but I guess my one question is how much does the slowness of debug relate to HOW it will be slow in release? Since release optimizations can do pretty radical things to the assembly generated it feels like it wouldn't really be apples to apples.
  - Leherenn 7y ago
    I thought it would be an issue as well at first, but it has really rarely been an issue. The performance degradation might not be even, but generally it approximates pretty well a slower system, without having to use a slower system in my experience. You can deal with the few edge cases individually. If you really care about performance on slower computers, then at some point you'll need to use one for real. But at least this way you have a fast feedback loop.

steveklabnik 7y ago

This already happens a bunch, even with the current setups. It's very natural if you come from a compiled language, and not if you don't. The first step of someone saying "hey why is Rust slow?" is five people replying "did you use --release".

sfink 7y ago
Can confirm. I had a graph traversal program written in Python. I ported it to Rust, and the runtime was identical -- 68.4 seconds, down to the tenth of a second. (Kinda blew my mind -- I had to triple check that I was running and timing what I thought I was!) I had a bit of a crisis of faith. I poked at it a few times over the next week, then finally got on the IRC channel and quickly received the advice mentioned above. Same input, with --release: 6.2 seconds.

Leherenn 7y ago

It's funny, because I do the exact opposite. As a developer I usually have a pretty powerful machine, and I've found that debug mode is a good way to approximate slow computers, and something that is unbearably slow in debug will bother some users later on.

runevault 7y ago
This is an interesting idea, but I guess my one question is how much does the slowness of debug relate to HOW it will be slow in release? Since release optimizations can do pretty radical things to the assembly generated it feels like it wouldn't really be apples to apples.
- Leherenn 7y ago
  I thought it would be an issue as well at first, but it has really rarely been an issue. The performance degradation might not be even, but generally it approximates pretty well a slower system, without having to use a slower system in my experience. You can deal with the few edge cases individually. If you really care about performance on slower computers, then at some point you'll need to use one for real. But at least this way you have a fast feedback loop.