16.1. Main updates (not on release branches yet)

This file generally contains all the updates for Open MPI that have not yet appeared on a release branch. It reflects active development, and is therefore a “loose” listing of features and changes. It is not considered definitive.

16.1.1. Open MPI version main

MPIR API has been removed

As was announced in summer 2017, Open MPI has removed support of MPIR-based tools beginning with the release of Open MPI v5.0.0.

The new PRRTE based runtime environment supports PMIx-tools API instead of the legacy MPIR API for debugging parallel jobs.

see https://github.com/openpmix/mpir-to-pmix-guide for more information

zlib is suggested for better user experience

PMIx will optionally use zlib to compress large data streams. This may result in shorter-than-normal startup times and smaller memory footprints. It is recommended to install zlib and zlib-devel for a better user experience.