What are shared arrays in Julia?

Julia is an open-source language that is dynamic, fast, and user-friendly.

A shared array uses memory that has been shared with the system to map the same array across many processes. In SharedArray, each process has access to the entire array.

A shared array is beneficial when we have to make large amounts of data jointly accessible to multiple processes on the same machine.

SharedArray{T}(dims::NTuple; init=false, pids=Int[])
SharedArray{T,N}(...)

• T: This is the bits type.
• dims: This is the size.
• pids: These specify these processes. The processes are on the same host.
• N: The value for this has to be the same as dims.

Note: When pids is not provided, the shared array is mapped across all processes, including the master process.

SharedArray{T}(file::AbstractString, dims::NTuple, [offset=0]; mode=nothing, init=false, pids=Int[])
SharedArray{T,N}(...)

In this scenario, the shared array is backed by the file with the filename, with size dims, element type T (must be a bits type), processes that are specified by pids, and all the processes must be on the same host. The file is going to be mapped into the host memory with the following implications:

1. The array data is to be in binary format.

2. If a change is made to the array values, the values on the disk would also change.

The mode can only be one of r, r+, w+, and a+. If the filename is not specified, the mode will be w+, otherwise by default it is r+.

The offset permits us to skip a given number of bytes at the beginning of the file.