Crate mpi

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Message Passing Interface bindings for Rust

The Message Passing Interface (MPI) is a specification for a message-passing style concurrency library. Implementations of MPI are often used to structure parallel computation on High Performance Computing systems. The MPI specification describes bindings for the C programming language (and through it C++) as well as for the Fortran programming language. This library tries to bridge the gap into a more rustic world.


Add the mpi crate as a dependency in your Cargo.toml:

mpi = "0.6"

Then use it in your program like this:

extern crate mpi;

use mpi::traits::*;

fn main() {
    let universe = mpi::initialize().unwrap();
    let world =;
    let size = world.size();
    let rank = world.rank();

    if size != 2 {
        panic!("Size of MPI_COMM_WORLD must be 2, but is {}!", size);

    match rank {
        0 => {
            let msg = vec![4.0f64, 8.0, 15.0];
            world.process_at_rank(rank + 1).send(&msg[..]);
        1 => {
            let (msg, status) = world.any_process().receive_vec::<f64>();
            println!("Process {} got message {:?}.\nStatus is: {:?}", rank, msg, status);
        _ => unreachable!()


The bindings follow the MPI 3.1 specification.

Currently supported:

  • Groups, Contexts, Communicators:
    • Group and (Intra-)Communicator management from section 6 is mostly complete.
    • no Inter-Communicators
    • no process topologies
  • Point to point communication:
    • standard, buffered, synchronous and ready mode send in blocking and non-blocking variants
    • receive in blocking and non-blocking variants
    • send-receive
    • probe
    • matched probe/receive
  • Collective communication:
    • barrier
    • broadcast
    • (all) gather
    • scatter
    • all to all
    • varying counts operations
    • reductions/scans
    • blocking and non-blocking variants
  • Datatypes: Bridging between Rust types and MPI basic types as well as custom MPI datatypes which can act as views into buffers.

Not supported (yet):

  • Process management
  • One-sided communication (RMA)
  • MPI parallel I/O
  • A million small things

The sub-modules contain a more detailed description of which features are and are not supported.

Further Reading

While every publicly defined item in this crate should have some documentation attached to it, most of the descriptions are quite terse for now and to the uninitiated will only make sense in combination with the MPI specification.


pub use crate::topology::Rank;


Collective communication

The core function of MPI is getting data from point A to point B (where A and B are e.g. single processes, multiple processes, the filesystem, …). It offers facilities to describe that data (layout in memory, behavior under certain operators) that go beyound a start address and a number of bytes.

Environmental management

The raw C language MPI API

Point to point communication

Bridge between rust types and raw values

Request objects for non-blocking operations

Organizing processes as groups and communicators

Re-exports all traits.


Describes the various levels of multithreading that can be supported by an MPI library.


Initialize MPI.

Initialize MPI with desired level of multithreading support.

Time in seconds since an arbitrary time in the past.

Resolution of timer used in time() in seconds

Type Definitions

An address in memory

Encodes number of values in multi-value messages.

Encodes error values returned by MPI functions.

Can be used to tag messages on the sender side and match on the receiver side.