Julia v1.9.0-beta2 is fast

General Usage Performance
41

In this case, for the second call measuring TTFX yes. I can’t remember where this discussion took place but looking at the docs is helpful Essentials · The Julia Language for the time macro.

In some cases the system will look inside the @time expression and compile some of the called code before execution of the top-level expression begins. When that happens, some compilation time will not be counted. To include this time you can run @time @eval ....

… is the relevant section. So using just time in the second call doesn’t include some of the compile time.

julia> @time using Bessels
  0.022755 seconds (22.24 k allocations: 2.378 MiB)

# main difference
julia> @time besselj(1.2, 8.2)
  0.000004 seconds
0.21735942469289246
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42 
julia> @macroexpand @time 1
quote
    #= timing.jl:263 =#
    begin
        #= timing.jl:268 =#
        $(Expr(:meta, :force_compile))

@time compiles the block it is in.
Given that the block includes the expression you’re timing, that often means it can be compiled before timing.

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43

That’s an amazing speed up!

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44

It’s pretty much the perfect example. There’s a bunch of code that was perfectly inferred and has no invalidation. All of the methods are concrete so there’s no reason at all to need to recompile anything.

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45

Yep. You might wonder if that might be possible only with fairly small examples that are “pure” functions. But we even got the same 1000x-scale speedup for ImageFiltering.imfilter, which is a pretty complicated function (basically the entire 1500-line source file src/imfilter.jl, though not all dispatch chains touch every method in that file). Use SnoopPrecompile for precompilation by timholy · Pull Request #255 · JuliaImages/ImageFiltering.jl · GitHub. And there might be actual computation setting the floor of the benefit; imfilter does actually take execution time…

Of course, I’ve stamped out invalidations in much of “my” code base a long time ago, which is why you get such dramatic improvements when you can flip the switch on native compilation.

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