SIHSort API

function mpisort!(
    v::AbstractVector;
    alg::SIHSort,
    by=identity,
    kws...
)

Distributed MPI-based sorting API with the same inputs as the base Julia sorters.

Important: the input vector will be mutated, but the sorted elements for each MPI rank will be returned; this is required as the vector size will change with data migration.

Additional keywords kws... are forwarded to the local sorter and searchsortedlast.

Examples

Different sorting settings:

# Automatically uses MPI.COMM_WORLD as communicator; doesn't save sorting stats
sorted_local_array = mpisort!(local_array; alg=SIHSort())

# Reverse sorting; specify communicator explicitly
sorted_local_array = mpisort!(local_array; alg=SIHSort(comm), rev=true)

# Specify key to sort by; see https://docs.julialang.org/en/v1/base/sort/
sorted_local_array = mpisort!(local_array; alg=SIHSort(), by=x->x["key"])

# Different ordering; see https://docs.julialang.org/en/v1/base/sort/#Alternate-orderings
sorted_local_array = mpisort!(local_array; alg=SIHSort(), order=Reverse)

# Save sorting stats
alg = SIHSort(comm)
sorted_local_array = mpisort!(local_array; alg=alg)

@show alg.stats.splitters               # `nranks - 1` elements splitting arrays between nodes
@show alg.stats.num_elements            # `nranks` integers specifying number of elements on each node

# Use different in-place local sorter
alg = SIHSort(comm, nothing)            # Default: standard Base.sort!
alg = SIHSort(comm, QuickSort)          # Specify algorithm, passed to Base.sort!(...; alg=<Algorithm>)
alg = SIHSort(comm, v -> mysorter!(v))  # Pass any function that sorts a local vector in-place

struct SIHSort <: Base.Sort.Algorithm

Sampling with interpolated histograms sorting algorithm, or SIHSort (pronounce sigh sort).

Methods

SIHSort(comm)
SIHSort(comm, sorter)
SIHSort(;comm=MPI.COMM_WORLD, sorter=nothing, stats=SIHSortStats())

Fields

• comm::MPI.Comm: MPI communicator used. Default: MPI.COMM_WORLD

• root::Int64: MPI root rank for reductions. Default: 0

• sorter::Union{Nothing, Function, Base.Sort.Algorithm}: Local in-place sorter used. Default: nothing

• stats::SIHSortStats: Useful stats saved after sorting, e.g. elements' partitioning. Default: SIHSortStats()

mutable struct SIHSortStats

Useful stats saved after sorting.

Methods

SIHSortStats(splitters, num_elements)
SIHSortStats(;splitters=nothing, num_elements=nothing)

Fields

• splitters::Union{Nothing, Vector}: Values used to split elements across MPI ranks, length=nranks - 1 Default: nothing

• num_elements::Union{Nothing, Vector{Int64}}: Number of elements saved locally to each MPI rank, length=nranks. Default: nothing