Why does the MPI backend require compiling from source?

[nathanbrown-Arm (Nathan Brown)]

Hello,

PyTorch has a built-in MPI backend, which is only available if PyTorch is compiled from source on a system which has an MPI implementation already installed link1, link2. Why can’t PyTorch ship with a default MPI implementation and enable the MPI backend without requiring compiling from source?

link1 states “Unfortunately, PyTorch’s binaries cannot include an MPI implementation”, but does not expand as to why.

[trusira]

@nathanbrown-Arm

Unfortunately, PyTorch’s binaries cannot include an MPI implementation

Likely due to licensing reasons with respect to software distribution.

[Honnappa (Honnappa Nagarahalli)]

May be due to there being several implementations of MPI?