I posted an issue <https://github.com/JuliaParallel/DistributedArrays.jl/issues/7> on the DArrays repo but someone in IRC suggested opening a thread here as well. I'm seeing different results from map vs pmap on a DArray in Julia 0.4.0-dev+3844 on Linux. When I run, on 6 procs:
julia> testa = drand(36) 36-element DistributedArrays.DArray{Float64,1,Array{Float64,1}}: 0.636737 0.275769 0.961624 0.427848 0.668537 0.0215699 0.292591 0.487622 0.54222 0.579438 0.299413 0.0699156 0.985861 0.642223 0.0108336 0.466572 0.134984 0.0718047 0.600704 0.367337 0.722101 0.96763 0.427482 0.963513 0.467348 0.987774 0.773584 0.531576 0.0155698 0.383172 0.0347603 0.299581 0.0226568 0.687901 0.22271 0.238291 julia> testb = drand(36) 36-element DistributedArrays.DArray{Float64,1,Array{Float64,1}}: 0.933919 0.445692 0.0028197 0.722083 0.088373 0.820338 0.71782 0.972424 0.623399 0.157076 0.657007 0.0753378 0.712683 0.303925 0.591726 0.320129 0.5457 0.00830437 0.0753483 0.973917 0.171903 0.291315 0.875653 0.0619788 0.53868 0.069952 0.534305 0.798335 0.923633 0.239445 0.748613 0.00554521 0.650063 0.770877 0.237519 0.414616 julia> pmap( (x) -> (x*x), testa) 175-element Array{Any,1}: 0.405433 0.405433 0.405433 0.405433 0.405433 0.405433 0.0760486 0.0760486 0.0760486 0.0760486 0.0760486 0.0760486 0.92472 0.92472 0.92472 0.183054 0.183054 0.183054 0.92472 0.183054 0.183054 0.183054 0.446942 0.446942 0.446942 0.446942 0.000465259 0.446942 ⋮ 0.00120828 0.00120828 0.00120828 0.00120828 0.00120828 0.00120828 0.0897485 0.0897485 0.0897485 0.0897485 0.0897485 0.000513332 0.000513332 0.473207 0.000513332 0.000513332 0.473207 0.473207 0.473207 0.0495998 0.473207 0.0495998 0.0495998 0.0495998 0.0567826 0.0567826 0.0567826 0.0567826 julia> map( (x) -> (x*x), testb) 36-element DistributedArrays.DArray{Float64,1,Array{Float64,1}}: 0.872205 0.198641 7.95072e-6 0.521403 0.00780978 0.672954 0.515266 0.945609 0.388626 0.0246728 0.431658 0.00567578 0.507917 0.0923703 0.35014 0.102483 0.297789 6.89625e-5 0.00567737 0.948514 0.0295506 0.0848642 0.766769 0.00384137 0.290177 0.00489328 0.285482 0.637339 0.853098 0.0573337 0.560421 3.07494e-5 0.422581 0.594251 0.0564152 0.171907 My intuition is that pmap and map on a DArray should do the same thing, and they did in 0.3.6. Searching through the source for DArrays, it appears I'm only supposed to use map? Which is fine, but should there be a note in the docs about it?