Tpetra::Distributor: Fix #3580
Created by: mhoemmen
@trilinos/tpetra @jjellio
Description
Fix #3580, by making all instances of the "slow path" in Distributor use a buffer long enough for all the messages, not just one at a time. Ignore the "Send type" and "Barrier between..." options, and always use MPI_Isend
for sends.
- Closes #3580
How Has This Been Tested?
Mac, Clang, OpenMPI.