core: Workaround for MPI serialization bug on 1 rank

See details in espressomd#4663
jngrad · Mar 10, 2023 · 3da215b · 3da215b
1 parent 02d4929
commit 3da215b
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Showing 2 changed files with 8 additions and 5 deletions.
diff --git a/src/core/bond_breakage/bond_breakage.cpp b/src/core/bond_breakage/bond_breakage.cpp
@@ -107,8 +107,10 @@ void clear_queue() { queue.clear(); }
 /** @brief Gathers combined queue from all mpi ranks */
 Queue gather_global_queue(Queue const &local_queue) {
   Queue res = local_queue;
-  Utils::Mpi::gather_buffer(res, comm_cart);
-  boost::mpi::broadcast(comm_cart, res, 0);
+  if (comm_cart.size() > 1) {
+    Utils::Mpi::gather_buffer(res, comm_cart);
+    boost::mpi::broadcast(comm_cart, res, 0);
+  }
   return res;
 }
 

diff --git a/src/core/collision.cpp b/src/core/collision.cpp
@@ -397,9 +397,10 @@ void glue_to_surface_bind_part_to_vs(const Particle *const p1,
 
 std::vector<CollisionPair> gather_global_collision_queue() {
   std::vector<CollisionPair> res = local_collision_queue;
-  Utils::Mpi::gather_buffer(res, comm_cart);
-  boost::mpi::broadcast(comm_cart, res, 0);
-
+  if (comm_cart.size() > 1) {
+    Utils::Mpi::gather_buffer(res, comm_cart);
+    boost::mpi::broadcast(comm_cart, res, 0);
+  }
   return res;
 }