The type of the array being returned seems to be determined by the
"similar" function:
julia> sa = SharedArray(Float64, 5, init = S -> S[Base.localindexes(S)] = 0)
5-element SharedArray{Float64,1}:
0.0
0.0
0.0
0.0
0.0
julia> typeof(similar(sa))
Array{Float64,1}
Perhaps that is the underlying issue.
On Monday, 21 December 2015 14:00:46 UTC-4, Daniel Arndt wrote:
>
> I've been trying to isolate a defect I have in my code for the past couple
> days, and it seems like SharedArrays have troubles with deepcopying.
>
> Looking at the source, this should be supported (Julia 0.4.2):
>
> https://github.com/JuliaLang/julia/blob/v0.4.2/base/sharedarray.jl#L201
>
> I've created a small stripped down version of the problem I am
> encountering.
>
> type A
> sa::SharedArray{Float64,1}
> end
>
>
> function A(n::Int)
> sa = SharedArray(Float64, n, init = S -> S[Base.localindexes(S)] = 0)
> return A(sa)
> end
>
> function Base.show(io::IO, a::A)
> print(io,a.sa)
> end
>
> function foo(a::A)
> for i in 1:length(a.sa)
> a.sa[i] += 1
> end
> end
>
> There are a few ways I can break this.
>
> 1. Calling @show on a deepcopy breaks when implemented like this.
> instance = A(5)
> @show instance
> dc = deepcopy(instance); # Semi-colon necessary on REPL to prevent show
> being called
> print(dc.sa) # Works fine
> @show dc.sa # Works fine
> @show dc # Seg fault if show is implemented
>
> Very strangely, a switch to "println" instead of "print" in the show
> function and everything works fine.
>
> 2. Even more worrysome, accessing the array in a function (foo):
> instance = A(5)
> dc = deepcopy(instance); # Semi-colon necessary on REPL to prevent show
> being called
> foo(instance) # Works fine on the original
> for i in 1:length(dc.sa)
> dc.sa[i] += 1
> end
> dc.sa # The above worked, and everything prints out fine
> foo(dc) #Seg fault
>
> It turns out, the deepcopy is creating the SharedArray as an Array:
>
> julia> instance = A(5)
> [0.0,0.0,0.0,0.0,0.0]
>
> julia> dc = deepcopy(instance);
>
> julia> typeof(instance)
> A
>
> julia> typeof(instance.sa)
> SharedArray{Float64,1}
>
> julia> typeof(dc)
> A
>
> julia> typeof(dc.sa)
> Array{Float64,1}
>
> Probably related? Is this a bug or am I doing something silly? Is anyone
> aware of a defect open for this or something similar, or should I open a
> new one?
>
> Cheers,
> Dan
>
