How to improve polygon rendering performance?

[roland-KA]

I've made a Pluto notebook which reads the shapes of all countries (using Shapefile) from Natural Earth and renders them, thus creating a world map.

I've used AoG for this purpose but implemented the same script also using the following packages:

• MeshViz which is (like AoG) based on Makie
• Gadfly
• Plots

Code using AoG

using AlgebraOfGraphics, GLMakie
using Shapefile, ZipFile
using Downloads: download

zipfile = download("https://www.naturalearthdata.com/http//www.naturalearthdata.com/download/110m/cultural/ne_110m_admin_0_countries.zip")

r = ZipFile.Reader(zipfile);
for f in r.files
    println("Filename: $(f.name)")
    open(f.name, "w") do io
    	write(io, read(f))
    end
end
close(r)

countries = Shapefile.Table("./ne_110m_admin_0_countries.shp")
plt = geodata(countries) * mapping(:geometry, color = :NAME_ID) * visual(Poly)
fg = draw(plt, legend=(position=:top,); axis=(width = 1400, height = 900))

Versioninfo:

Julia Version 1.6.1
Commit 6aaedecc44 (2021-04-23 05:59 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin18.7.0)
  CPU: Apple M1
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, westmere)

Surprisingly, the different implementations showed vastly differing run time performances for drawing the map (consisting of 290 polygons). As in almost all Julia programs the first execution is much slower than on follow up runs, I measured execution times for the first as well as for the next run of each script and got the following numbers (all times are in seconds):

Implementation	1st run	2nd run
AoG + GLMakie	96	50
AoG + CairoMakie	95	50
MeshViz + GLMakie	55	2.5
MeshViz + CairoMakie	54	3
Plots	2	0.1
Gadfly	1	< 0.001

As can bee seen all Makie-based implementations are generally slower (why?). But there is also a noticeable difference between AoG and MeshViz, despite being based on Makie in both cases. Especially on the 2nd run AoG lacks the speedup which can be seen in MeshViz.

So I wonder if anything can be changed in my implementation using AoG to get a better performance?

[jkrumbiegel]

I've looked into this just now and while the times are better on my machine, they're still bad. I did this:

@time begin
    plt = data(countries) * mapping(:geometry, color = :NAME_ID) * visual(Choropleth)
    fg = draw(plt, scales(Color = (; legend = false)), legend=(position=:top,))
    display(fg)
end

Note the Color = (; legend = false). Without that (so with the legend showing) I get 7.962373 seconds (53.77 M allocations: 2.181 GiB, 3.35% gc time, 0.00% compilation time). With it (so no legend) I get 0.194179 seconds (678.70 k allocations: 56.869 MiB, 18.62% gc time, 0.00% compilation time). So the slowness here is basically all legend. Of course, there are 177 legend entries, which is a lot, so the underlying slowness of Legend is compounded, probably quadratically.

I'll close this here as I'm pretty sure the issue is on Makie's side.

[roland-KA]

Ok, thanks. Then we know at least where the problem is.