UndefVarError when initializing variable inside function with @everywhere

Specific Domains Julia at Scale
4

Just pre-allocate A outside of the function. The @everywhere macro executes just the statement that is passed to it, so A will be in global scope on the child processes anyway.

The code below works, regardless of whether addprocs were called or not.

using Distributed
addprocs(4)
@everywhere using LinearAlgebra, Random

@everywhere A = zeros(100, 100)

@everywhere function h!(x)

    return eigvals(rand!(MersenneTwister(x), A))

end

function run_h(iter)
    if nprocs()>1
        return pmap(x->h!(x), iter)
    else
        return map(x->h!(x), iter)
    end
end