Fast parallel broadcast and reduction operations for Julia using binary-tree algorithms. Note that we can broadcast and reduce over any Julia type, but we provide convenience methods for performing these operations on Julia arrays.


The bcast method copies an object to a set of machines. The object can be either an array or a composite structure. The broadcasted object is stored as an Dict{Int,Future} using the TypeFutures struct. We retrieve the local part of the TypeFuture using the fetch method.


The reduce! method, reduces a TypeFuture across all participating workers. The reduction follows the reducemethod! which is an optional argument to reduce!. By default the reduction is a element-wise addition (i.e. .+=). This is appropriate for our most common use case where each item in TypeFuture is an array of a common size and type. In this case the resulting reduction is another array of that same common size and type.

Please note that reduce! mutates the TypeFuture that it is applied to. Hence, calling reduce! twice on the same TypeFuture will produce different results.

Similar packages

There are other packages that provide similar (but not equivalent) functionality, and it may be worth thinking about how to consolidate efforts in the future:

  • ParallelOperations.jl - https://github.com/JuliaAstroSim/ParallelOperations.jl
  • ParallelDataTransfer.jl - https://github.com/ChrisRackauckas/ParallelDataTransfer.jl
  • ArrayChannels.jl - https://github.com/rohanmclure/ArrayChannels.jl