Prevents calling MPI_Comm_free after MPI_Finalize.

With OpenMPI there appeared cases where MPI_Comm_free
was called after MPI_Finalize. This was caused by the
destructor of OwnerOverlapCopyCommunication being called
after MPI_Finalize.
This patch moves the destruction out of the main method.
If MPI 2 functionality is available we also check whether
MPI_Finalize was called before freeing the communicator and
only call free if not.

dune/istl/owneroverlapcopy.hh

@@ -662,7 +662,17 @@ namespace Dune {
       if (globalLookup_) delete globalLookup_;
       if (freecomm==true)
         if(comm!=MPI_COMM_NULL)
+        {
+#ifdef MPI_2
+          // If it is possible to query whether MPI_Finalize
+          // was called, only free the communicator before
+          // calling MPI_Finalize.
+          int wasFinalized = 0;
+          MPI_Finalized( &wasFinalized );
+          if(!wasFinalized)
+#endif
           MPI_Comm_free(&comm);
+        }
     }
 
   private:

dune/istl/paamg/test/hierarchytest.cc

@@ -11,20 +11,9 @@
 #include <dune/istl/schwarz.hh>
 #include "anisotropic.hh"
 
-int main(int argc, char** argv)
+template<int BS>
+void testHierarchy(int N)
 {
-  MPI_Init(&argc, &argv);
-
-  const int BS=1;
-  int N=10;
-
-  if(argc>1)
-    N = atoi(argv[1]);
-
-  int procs, rank;
-  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
-  MPI_Comm_size(MPI_COMM_WORLD, &procs);
-
   typedef int LocalId;
   typedef int GlobalId;
   typedef Dune::OwnerOverlapCopyCommunication<LocalId,GlobalId> Communication;
@@ -63,7 +52,7 @@ int main(int argc, char** argv)
   Criterion criterion(100,4);
   Dune::Timer timer;
 
-  hierarchy.build<OverlapFlags>(criterion);
+  hierarchy.template build<OverlapFlags>(criterion);
   hierarchy.coarsenVector(vh);
 
   std::cout<<"Building hierarchy took "<<timer.elapsed()<<std::endl;
@@ -77,6 +66,24 @@ int main(int argc, char** argv)
   std::vector<std::size_t> data;
 
   hierarchy.getCoarsestAggregatesOnFinest(data);
+}
+
+
+int main(int argc, char** argv)
+{
+  MPI_Init(&argc, &argv);
+
+  const int BS=1;
+  int N=10;
+
+  if(argc>1)
+    N = atoi(argv[1]);
+
+  int procs, rank;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Comm_size(MPI_COMM_WORLD, &procs);
+
+  testHierarchy<BS>(N);
 
   MPI_Finalize();