Speed up compilation by 22% by compiling serde_derive earlier
#101
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Enselic
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Thanks, yeah, I've been aware of this general strategy to parallelize builds. Will look at this and at the CI failure when I'm next at a computer. |
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(The build failure is fixed.) Looking at this in more detail, what do you think of just hand-writing the |
Enabling the "derive" feature of `serde` means `serde_derive` must
compile before `serde`. But `serde` does not depend on `serde_derive`.
Instead depend on `serde_derive` directly so `serde` and `serde_derive`
can compile in parallel. That speeds up compilation by 22%:
Before:
$ hyperfine --prepare 'cargo clean' 'cargo build --all-features'
Benchmark 1: cargo build --all-features
Time (mean ± σ): 4.940 s ± 0.101 s [User: 15.523 s, System: 3.558 s]
Range (min … max): 4.773 s … 5.098 s 10 runs
After:
$ hyperfine --prepare 'cargo clean' 'cargo build --all-features'
Benchmark 1: cargo build --all-features
Time (mean ± σ): 3.831 s ± 0.138 s [User: 16.185 s, System: 3.602 s]
Range (min … max): 3.606 s … 4.040 s 10 runs
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(Thanks!) Since the use of |
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Thanks. I think I'd like to drop serde_derive altogether anyway just because it's so straightforward. I'll land your change and then make another one on top to drop it. |
sunshowers
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Continuing work from #101, we can just hand-write the `Utf8PathBuf` impl. Before: ``` % hyperfine --prepare 'cargo clean' 'cargo build --features serde1' Benchmark 1: cargo build --features serde1 Time (mean ± σ): 2.454 s ± 0.028 s [User: 3.928 s, System: 0.964 s] Range (min … max): 2.394 s … 2.484 s 10 runs ``` After: ``` % hyperfine --prepare 'cargo clean' 'cargo build --features serde1' Benchmark 1: cargo build --features serde1 Time (mean ± σ): 1.445 s ± 0.013 s [User: 1.415 s, System: 0.406 s] Range (min … max): 1.427 s … 1.462 s 10 runs ```
sunshowers
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Jun 2, 2025
Continuing work from #101, we can just hand-write the `Utf8PathBuf` impl. Before: ``` % hyperfine --prepare 'cargo clean' 'cargo build --features serde1' Benchmark 1: cargo build --features serde1 Time (mean ± σ): 2.454 s ± 0.028 s [User: 3.928 s, System: 0.964 s] Range (min … max): 2.394 s … 2.484 s 10 runs ``` After: ``` % hyperfine --prepare 'cargo clean' 'cargo build --features serde1' Benchmark 1: cargo build --features serde1 Time (mean ± σ): 1.445 s ± 0.013 s [User: 1.415 s, System: 0.406 s] Range (min … max): 1.427 s … 1.462 s 10 runs ```
sunshowers
added a commit
that referenced
this pull request
Jun 2, 2025
Continuing work from #101, we can just hand-write the `Utf8PathBuf` impl. Before: ``` % hyperfine --prepare 'cargo clean' 'cargo build --features serde1' Benchmark 1: cargo build --features serde1 Time (mean ± σ): 2.454 s ± 0.028 s [User: 3.928 s, System: 0.964 s] Range (min … max): 2.394 s … 2.484 s 10 runs ``` After: ``` % hyperfine --prepare 'cargo clean' 'cargo build --features serde1' Benchmark 1: cargo build --features serde1 Time (mean ± σ): 1.445 s ± 0.013 s [User: 1.415 s, System: 0.406 s] Range (min … max): 1.427 s … 1.462 s 10 runs ```
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Now out as camino-1.1.10. Thanks again! |
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(Sorry, missed that last comment.) Happy to help! Thanks for the quick release! |
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Hi! Enabling the "derive" feature of
serdemeansserde_derivemust compile beforeserde. Butserdedoes not depend onserde_derive. So this is an artifical and unnecessary dependency chain. Instead depend onserde_derivedirectly soserdeandserde_derive(and its direct dependencies) can compile in parallel. That speeds up compilation by 22% (see below).The maintainer of serde did the same change for bat a while ago: sharkdp/bat#2815
This does not only help camino build faster, but all downstream projects that directly or indirectly depend on camino. Without this fix, downstream projects can't speed up their builds in the same way since cargo features are additive.
Before
After