That seems to be it. I'll prepare an issue and pull request. Thanks for the
rubber duck debugging!
On Monday, 21 December 2015 14:44:58 UTC-4, Daniel Arndt wrote:
>
> 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
>>
>
