v1.9 rc1 significant slowdown in garbage collection #49120
Description
I have a significant slowdown for some code in Julia 1.9 rc1 which I could track down to garbage collection during filling of arrays. There seems to be something fishy with v1.9 rc1.
Below is some reduced code to reproduce the issue. The garbage collection is here significantly slower for Julia 1.9 compared to previous versions.
Total runtime for ´julia test.jl' on my machine is
- around 5 s for Julia 1.8
- around 94 s for Julia 1.9
using Random: seed!
seed!(1)
abstract type Cell end
struct CellA<:Cell
a::Int
end
struct CellB<:Cell
b::String
end
function fillcells!(mc::Array{Cell})
for ind in eachindex(mc)
mc[ind] = ifelse(rand() > 0.5, CellA(ind), CellB(string(ind)))
end
return mc
end
mcells = Array{Cell}(undef, 5000, 5000 )
t1 = @elapsed fillcells!(mcells)
t2 = @elapsed fillcells!(mcells)
println("filling: $t1 s\nfilling again: $t2 s")I saw some GC issues in #48923 , not sure if this is related. If so, let me know and I will close this.