How to write to multiple indices of an array at the same time in Julia?

问题

I would like to see something like this working in Julia:

using Distributed
addprocs(4)

@everywhere arr = Array{Int}(undef, 10)
for i = 1:10
    @spawn arr[i] = i
end

What is the proper way of doing this?

回答1:

You have the following ways to parallelize the process.

1. Threads (requires setting JULIA_NUM_THREADS system variable)

   arr = Array{Int}(undef, 10)
   Threads.@threads for i = 1:10
       arr[i] = i
   end
   

2. SharedArrays

   using Distributed, SharedArrays
   addprocs(4)
   arr = SharedVector{Int}(10)
   @sync @distributed for i in 1:10
       arr[i] = i 
   end
   

   Note that a common error is to forget to place @sync before @distributed that does not have an aggregator function (see the last example).

3. Aggregate the results of your distributed computation

   using Distributed
   addprocs(4)
   arr = @distributed (append!) for i in 1:10
       [i]
   end
   

来源：https://stackoverflow.com/questions/64499815/how-to-write-to-multiple-indices-of-an-array-at-the-same-time-in-julia