Precompile to reduce latency

[timholy]

Motivated by JuliaLang/julia#43990 (comment),
but probably not a bad idea in its own right.

[codecov]

Codecov Report

Merging #28 (c52b1f2) into master (72ad73e) will decrease coverage by 0.22%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #28      +/-   ##
==========================================
- Coverage   75.67%   75.45%   -0.23%     
==========================================
  Files           2        2              
  Lines         111      110       -1     
==========================================
- Hits           84       83       -1     
  Misses         27       27              

Impacted Files	Coverage Δ
src/Preferences.jl	73.56% <ø> (-2.23%)	⬇️
src/utils.jl	82.60% <100.00%> (+7.60%)	⬆️

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[giordano]

With Julia v1.7.1, on master (same as v1.2.3):

% julia --project=/tmp --startup-file=no -q
julia> @time using GTK3_jll
  0.104612 seconds (367.33 k allocations: 17.839 MiB, 24.74% compilation time)

(same as JuliaPackaging/JLLWrappers.jl#38 (review))

This PR:

% julia --project=/tmp --startup-file=no -q
julia> @time using GTK3_jll
  0.126395 seconds (415.97 k allocations: 22.106 MiB, 20.87% compilation time)

This seems to go in the wrong direction?

[timholy]

Hmm, I can confirm that. It seems like the final precompilation is bad news. Try the latest?

[timholy]

Checked, commenting out that last one doesn't eat into the benefits for JuliaLang/julia#43990, if anything slightly improved.

[giordano]

Now it looks better:

% julia --project=/tmp --startup-file=no -q
julia> @time using GTK3_jll
  0.088641 seconds (271.73 k allocations: 15.071 MiB, 29.69% compilation time)

For reference, I got this timing after cleaning up the .julia/compiled directory. I did the same again before rerunning the benchmark for Preferences.j master:

% julia --project=/tmp --startup-file=no -q
julia> @time using GTK3_jll
  0.088586 seconds (270.22 k allocations: 14.794 MiB, 29.98% compilation time)

Memory allocations got just slightly worse, but the time is pretty much the same

[timholy]

I think this is even better. Hold off on merging, though, the hasmethod line may change.

[timholy]

Now that JuliaLang/julia#43990 has merged without further API changes, we can safely merge this.