CUDA.jl takes much much longer to load on Julia v1.12

[oschulz]

I'm seeing much longer package load times of CUDA.jl on Julia v1.12, compared to v1.11.

I've timed this on two very different systems (using fresh Julia installations on a local NVMe temp disk, an empty Pkg depot, etc):

Server, NVIDIA Grace-Hopper GH200, Ubuntu 24.04

Julia v1.11

$ time julia-1.11.7/bin/julia -e 'using CUDA'
real    0m3.108s
user    0m5.665s
sys     0m0.721s

julia> @time @time_imports import CUDA
[... fairly quick ...]
    535.6 ms  CUDA 3.41% compilation time
      0.3 ms  Atomix → AtomixCUDAExt
[delay here]
  2.626289 seconds (3.14 M allocations: 217.201 MiB, 10.50% gc time, 18.88% compilation time: 6% of which was recompilation)

Julia v1.12

$ time julia-1.12.2/bin/julia -e 'using CUDA'
real    0m14.615s
user    0m17.187s
sys     0m0.744s

julia> @time @time_imports import CUDA
[... fairly quick ...]
   1133.9 ms  CUDA 1.36% compilation time
      0.3 ms  Atomix → AtomixCUDAExt
[long delay here]
 14.621508 seconds (12.65 M allocations: 705.328 MiB, 4.97% gc time, 80.55% compilation time: 96% of which was recompilation)

Laptop, NVIDIA RTX 2000 Ada, Ubuntu 24.04

Julia v1.11

$ time julia-1.11 -e 'using CUDA'
real	0m7.348s
user	0m8.977s
sys	0m1.891s

julia> @time @time_imports import CUDA
[... fairly quick ...]
   1208.8 ms  CUDA 37.99% compilation time
      0.7 ms  Atomix → AtomixCUDAExt
[delay here]
  7.510932 seconds (3.92 M allocations: 253.427 MiB, 2.97% gc time, 43.74% compilation time: 19% of which was recompilation)

Julia v1.12

$ time julia-1.12 -e 'using CUDA'
real	0m37.247s
user	0m32.124s
sys	0m8.350s

julia> @time @time_imports import CUDA
[... fairly quick ...]
   1851.8 ms  CUDA 11.05% compilation time
      0.4 ms  Atomix → AtomixCUDAExt
[long delay here]
 29.482076 seconds (12.97 M allocations: 716.697 MiB, 1.12% gc time, 82.29% compilation time: 96% of which was recompilation)

When timing with @time @time_imports import CUDA, there is a long delay after the output of @time_imports ends, that's where most of the time is spent.

Is this a known issue?

(Not sure this is strictly a bug, but package load times near 30 seconds (sometimes almost 40, it varies a lot) can severely affect usability, especially when giving a presentation ...)

[ViralBShah]

There's a much larger number of allocations. Wonder if that points to invalidations.