A new beta release of MPICH, 4.0b1, is now available for download. This is the first beta release in the 4.0 series. This release is feature complete and includes support for all new MPI-4.0 APIs. The full set of changes since 4.0a2 can be found here: https://github.com/pmodels/mpich/compare/v4.0a2…v4.0b1.
Also in this release are several bugs fixes (thanks to user reports) and improvements in ch3, hydra, and common MPICH code. You can find the release on our downloads page.