buildRustCrate: remove superfluous dependency overrides #79816
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By overriding each dependency on every level of the dependency tree we are creating a lot of unnecessary instances of the same derivation Looking at the output size of `nix-instantiate --trace-function-calls -vvvv …` and the execution time I got about a 10x improvement after applying this change. It was probably good intentions that lead to these overrides but in practice no tooling (that I know of) really needs this. `carnix` and `crate2nix` are fine without those overrides. Furthermore I believe that it is the job of the tooling around `buildRustCrate` to provide a coherent set of overrides. By not enforcing all of the overrides, debug flags, verbosity, … to be the same throughout the closure we also allow consumers to override specific aspects of the crates. Some (older?) crates might need different `crateOverrides` then newer crates with the same name. Currently such situations can not (easily) be implemented with the override in-place.
nagisa
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to standard-ai/nixpkgs-tensorflow-rust
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Feb 11, 2020
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This indeed appears to be much faster for a large workspace: We do still instantiate the most depended-on crates dozens of times, but it is definitely more livable now. r+ |
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@GrahamcOfBorg eval |
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Motivation for this change
By overriding each dependency on every level of the dependency tree we
are creating a lot of unnecessary instances of the same derivation
Looking at the output size of
nix-instantiate --trace-function-calls -vvvv …and the execution time I got about a 10x improvement afterapplying this change.
It was probably good intentions that lead to these overrides but in
practice no tooling (that I know of) really needs this.
carnixandcrate2nixare fine without those overrides. Furthermore I believe thatit is the job of the tooling around
buildRustCrateto provide acoherent set of overrides. By not enforcing all of the overrides, debug
flags, verbosity, … to be the same throughout the closure we also allow
consumers to override specific aspects of the crates. Some (older?)
crates might need different
crateOverridesthen newer crates with thesame name. Currently such situations can not (easily) be implemented
with the override in-place.
cc nix-community/crate2nix#90 @nagisa @kolloch
Things done
sandboxinnix.confon non-NixOS linux)nix-shell -p nixpkgs-review --run "nixpkgs-review wip"./result/bin/)nix path-info -Sbefore and after)