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First time I hear about compile times being an issue with Rust. Is that a general problem with bigger projects or can you identify language features that add sp

First time I hear about compile times being an issue with Rust. Is that a general problem with bigger projects or can you identify language features that add specifically to the problem?

felipellrocha 7y ago
First compilation is slow. After that it’s much better during development times. This can mean that ci can take a ton of time if you don’t do even the smallest bit of optimization. Otherwise, it’s a solid language choice. L
- theanzelm 7y ago
  As a point of reference "warmed up" compilation for me still takes ~1minute. Bearable for general work, horrible for quick tweaks or UI-related work.
  - infogulch 7y ago
    I've heard that long warm compilation times can be mitigated by breaking up code into separate modules so it doesn't recompile e.g. the actor system every time you adjust a layout. Basically caching works best on the module boundary. Is this something you've explored?
    - z0mbie42 7y ago
      +1 I've splitted a 20k+LOC Rust project into multiple crates and compilation time improved a lot (still slow compared to other languages) but it's now manageable.
    - theanzelm 7y ago
      Yes, I factored out quite a bit of generic parts of the engine into libraries and took some steps to cut down on number of generics being instanced (which was one of the main drivers of compile time). Now I'm left with pretty much the game core, which is highly interdependent and thus nearly impossible to break up into crates (they can't mutually depend on each other). And it's still kinda slow.
  - jeanmichelx 7y ago
    I'm so jealous of software development tools. Elaborating the hardware (systemverilog) I'm working on (about a year of work from scratch, nothing fancy) takes 8 minutes.
    - jtms 7y ago
      Wow, I get frustrated and feel unproductive if my feedback loop is longer than 2-5 SECONDS. This must require a seriously different approach to trial and error exploration
      - dimfeld 7y ago
        A lot of that is done in a simulator on the computer, which usually builds very quick once you get the environment and simulation scripts written. The full build to a bit file that can be loaded into hardware is an NP-hard optimization problem, so as your design approaches the limits of either the desired clock speed or the amount of space in the chip, it can become very slow.
        jeanmichelx 7y ago
        I wish. This figure is reloading the formal tool after a one line change in the RTL. Placing (not routing!) takes around 24 hours since we need to run in a larger environment than just the block level to get realistic timing reports
Twirrim 7y ago
Really? It has been quite a talking point for a while with Rust. Final binary performance is great, but compilation times hurt badly.

First time I hear about compile times being an issue with Rust. Is that a general problem with bigger projects or can you identify language features that add specifically to the problem?

felipellrocha 7y ago

First compilation is slow. After that it’s much better during development times. This can mean that ci can take a ton of time if you don’t do even the smallest bit of optimization. Otherwise, it’s a solid language choice. L

theanzelm 7y ago
As a point of reference "warmed up" compilation for me still takes ~1minute. Bearable for general work, horrible for quick tweaks or UI-related work.
- infogulch 7y ago
  I've heard that long warm compilation times can be mitigated by breaking up code into separate modules so it doesn't recompile e.g. the actor system every time you adjust a layout. Basically caching works best on the module boundary. Is this something you've explored?
  - z0mbie42 7y ago
    +1 I've splitted a 20k+LOC Rust project into multiple crates and compilation time improved a lot (still slow compared to other languages) but it's now manageable.
  - theanzelm 7y ago
    Yes, I factored out quite a bit of generic parts of the engine into libraries and took some steps to cut down on number of generics being instanced (which was one of the main drivers of compile time). Now I'm left with pretty much the game core, which is highly interdependent and thus nearly impossible to break up into crates (they can't mutually depend on each other). And it's still kinda slow.
- jeanmichelx 7y ago
  I'm so jealous of software development tools. Elaborating the hardware (systemverilog) I'm working on (about a year of work from scratch, nothing fancy) takes 8 minutes.
  - jtms 7y ago
    Wow, I get frustrated and feel unproductive if my feedback loop is longer than 2-5 SECONDS. This must require a seriously different approach to trial and error exploration
    - dimfeld 7y ago
      A lot of that is done in a simulator on the computer, which usually builds very quick once you get the environment and simulation scripts written. The full build to a bit file that can be loaded into hardware is an NP-hard optimization problem, so as your design approaches the limits of either the desired clock speed or the amount of space in the chip, it can become very slow.
      - jeanmichelx 7y ago
        I wish. This figure is reloading the formal tool after a one line change in the RTL. Placing (not routing!) takes around 24 hours since we need to run in a larger environment than just the block level to get realistic timing reports

Twirrim 7y ago

Really? It has been quite a talking point for a while with Rust. Final binary performance is great, but compilation times hurt badly.