Always single thread

[andferrari]

I cannot manage to use multithreading on my CPU (with 56 cores and JULIA_NUM_THREADS=55):

julia> using ImageFiltering
julia> img = randn(10000, 10000);
julia> kernel = KernelFactors.gaussian((10, 10), (41, 41));
julia> im_f = imfilter(img, kernel);
julia> Threads.nthreads()
55

but htopshows only 1 active cpu. Multithreading e.g. with using LinearAlgebra works perfectly.

Thank you for your help!

[andferrari]

As it is written in the doc, multithreading is only for FIR filters