From fe3abd2ab264bc1c0cb40d3b6118f5739a92c438 Mon Sep 17 00:00:00 2001
From: Peter Munch <peterrmuench@gmail.com>
Date: Fri, 6 Nov 2020 09:05:54 +0100
Subject: [PATCH] Use mpi_processes_within_communicator

---
 source/matrix_free/vector_data_exchange.cc | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/source/matrix_free/vector_data_exchange.cc b/source/matrix_free/vector_data_exchange.cc
index f8ab1fe9b1..17939f8416 100644
--- a/source/matrix_free/vector_data_exchange.cc
+++ b/source/matrix_free/vector_data_exchange.cc
@@ -426,17 +426,8 @@ namespace internal
         std::vector<unsigned int> sm_import_data_this_indices;
 
         // collect ranks of processes of shared-memory domain
-        const auto sm_ranks = [&]() {
-          std::vector<unsigned int> sm_ranks(
-            Utilities::MPI::n_mpi_processes(comm_sm));
-
-          const unsigned int rank = Utilities::MPI::this_mpi_process(comm);
-
-          MPI_Allgather(
-            &rank, 1, MPI_UNSIGNED, sm_ranks.data(), 1, MPI_UNSIGNED, comm_sm);
-
-          return sm_ranks;
-        }();
+        const auto sm_ranks =
+          Utilities::MPI::mpi_processes_within_communicator(comm, comm_sm);
 
         // determine owners of ghost indices and determine requesters
         std::vector<unsigned int> owning_ranks_of_ghosts(
-- 
2.39.5