---
title: OpenMPI
breadcrumbs:
- title: Software Engineering
- title: Frameworks
---
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A Message Passing Interface (MPI) implementation for C, Fortran, Java, etc.

## Resources

- [Frequently Asked Questions (OpenMPI)](https://www.open-mpi.org/faq/)

## Installation

### Linux

**Ubuntu (APT):**

1. (Prerequisite) Install buid tools: `apt install build-essetial`
1. Install OpenMPI binaries, docs and libs: `apt install openmpi-bin openmpi-doc libopenmpi-dev`

## Build

- Compile and link with `mpicc` (C) or `mpic++` (C++), which will include OpenMPI options and libs.
- (Optional) Setup IDE to include MPI libs:
    - VS Code: Set `{"C_Cpp.default.includePath": ["${myDefaultIncludePath}","/usr/lib/x86_64-linux-gnu/openmpi/include/"]}` in your project settings (`.vscode/settings.json` or `~/.config/Code/User/settings.json`).

## Run

- Command: `mpirun [opts] <app> [app_opts]`
- To run it with `n` processes, specify `-n <n>`. Specify `-n $(nproc)` to use all cores. If it complains about "not enough slots", specify `--oversubscribe`.
- If you need to run it as root (strongly discouraged), specify `--allow-run-as-root`.

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