MPI_Comm_split with uninitialized key value?

[adammoody]

I'm working with @kosinovsky to debug an XOR rebuild problem. While looking through the code, this line caught my eye:

VELOC/src/lib/client.cpp

Line 62 in a5a9b8a

MPI_Comm_split(comm, provided == 0 ? 0 : MPI_UNDEFINED, rank, &backends);

I don't think rank has been initialized at this point, which means it could have an arbitrary value. That could then lead to a potential random reordering of rank values in the backends communicator as compared to the parent communicator.

A potential fix would be to replace rank with 0 or otherwise move the MPI_Comm_rank(comm, &rank) higher up in the function.

[bnicolae]

Correct, I've fixed it