`similar` does not produce a SharedArray when fed one

amrods · April 18, 2019, 11:45pm

Consider this:

using SharedArrays
x = SharedArray{Float64}(1, 1)
y = similar(x)

I would expect y to also be a SharedArray, however

julia> typeof(x)
SharedArray{Float64,2}

julia> typeof(y)
Array{Float64,2}

eliassno · April 19, 2019, 1:42am

The source array is actually an Array

github.com

JuliaLang/julia/blob/80516ca20297a67b996caa08c38786332379b6a5/stdlib/SharedArrays/src/SharedArrays.jl#L555


      
          shmem_rand(I::Int...; kwargs...) = shmem_rand(I; kwargs...)
          
          function shmem_randn(dims; kwargs...)
              SharedArray{Float64,length(dims)}(dims; init = S-> map!(x -> randn(), S.loc_subarr_1d, S.loc_subarr_1d), kwargs...)
          end
          shmem_randn(I::Int...; kwargs...) = shmem_randn(I; kwargs...)
          
          similar(S::SharedArray, T::Type, dims::Dims) = similar(S.s, T, dims)
          similar(S::SharedArray, T::Type) = similar(S.s, T, size(S))
          similar(S::SharedArray, dims::Dims) = similar(S.s, eltype(S), dims)
          similar(S::SharedArray) = similar(S.s, eltype(S), size(S))
          
          reduce(f, S::SharedArray) =
              mapreduce(fetch, f, Any[ @spawnat p reduce(f, S.loc_subarr_1d) for p in procs(S) ])
          
          reduce(::typeof(vcat), S::SharedVector) = invoke(reduce, Tuple{Any,SharedArray}, vcat, S)
          reduce(::typeof(hcat), S::SharedVector) = invoke(reduce, Tuple{Any,SharedArray}, hcat, S)
          
          function map!(f, S::SharedArray, Q::SharedArray)
              if (S !== Q) && (procs(S) != procs(Q) || localindices(S) != localindices(Q))
                  throw(ArgumentError("incompatible source and destination arguments"))

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