stan-dev / stan-dev/math

mpi_cluster constructor that allows other types of communicator

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feature mpi
Dominant language
C++
Stars
839
Forks
220
Avg merge
2d 4h
Merged PRs (30d)
14

Description

Summary:

Allows other types of mpi communicator used in mpi_cluster

Description:

Currently we only allow MPI_COMM_WORLD in MPI jobs. This is not enough if we want to mix Stan with other MPI-enabled libraries when Stan only utilized part of the MPI cluster in the whole cluster, or to allow Stan to dispatch part of cluster to a specific task. An application is when used with a PDE solver where there may be multiple groups of nodes, each of which running in its own communicator for part of the PDE problem.

Reproducible Steps:

n/a, new feature

Current Output:

n/a

Expected Output:

mpi_cluster uses user-supplied communicator.

Additional Information:

Provide any additional information here.

Current Version:

v2.18.0

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the mpi_cluster constructor and the existing handling of MPI_COMM_WORLD. Read the surrounding MPI integration and communicator usage before determining the API changes needed. Done means mpi_cluster accepts a user-supplied communicator so Stan can use a subset of an MPI cluster alongside other MPI-enabled work.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
distributed-systems
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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