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How to import all symbols from a module with @everywhere?
5 posts by 2 authors  



Ismael Venegas Castelló 	

9/26/15


Hello everyone!

I have been trying to do some parallel tests with a simple example using Images and Colors,  you can see here:
http://nbviewer.ipython.org/gist/Ismael-VC/e18bcae78a49f68a0838
ERROR (unhandled task failure): On worker 15:
UndefVarError: Gray not defined

The same on every worker.

It seems that the problem is the way I'm importing the modules? I do:

addprocs(CPU_CORES)

@everywhere importall Images, Colors

@everywhere function procesar_imagen(imagen::AbstractString, σ=2)
    imagen₁ = imread(imagen)
    imagen₂ = convert(Image{Gray}, imagen₁)
    σ₁ = [σ, σ]    # un valor de σ por cada dimensión
    imagen₃ = imfilter_gaussian(imagen₂, σ₁)
    imagen₄ = reinterpret(Float64, data(imagen₃))
    return var(imagen₄)
end

y = @time @parallel vcat for i = 1:100
    gc()    # llamar al recolector de basura
    procesar_imagen("imagen.jpg")
end

gc()

y

Thanks in advance.

Cheers!
 


Nils Gudat 	

9/26/15


The way to do this is

addprocs(CPU_CORES-1)
import Images, Colors
@everywhere using Images, Colors

I have to admit that I still don't understand the difference between import and using, but I think import doesn't make the exported functions available in the namespace of each worker, for that you'll need using.
 


Ismael Venegas Castelló 	

9/26/15


Thank you very much Nils, that solved my issue!
 


Ismael Venegas Castelló 	

9/26/15


This is the result:
* http://nbviewer.ipython.org/gist/Ismael-VC/3fa7fb19fff61b0c6eeb

530.838512 seconds (18.68 k allocations: 2.102 MB)

What's the advantage of  addprocs(CPU_CORES - 1) ?

 
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