Fixed partitioning issue with empty partitiones.

AMDiS/src/parallel/MeshDistributor.cc

@@ -1283,6 +1283,10 @@ namespace AMDiS {
       return;
     }
 
+    TEST_EXIT_DBG(!(partitioner->getSendElements().size() == mesh->getMacroElements().size() && 
+		    partitioner->getRecvElements().size() == 0))
+      ("Partition is empty, should not happen!\n");
+
     // === Create map that maps macro element indices to pointers to the ===
     // === macro elements.                                               ===
 

AMDiS/src/parallel/ZoltanPartitioner.cc

@@ -97,6 +97,13 @@ namespace AMDiS {
     recvElements.clear();
     sendElements.clear();
 
+    int createEmptyPartition = 
+      (mesh->getMacroElements().size() == nExportEls && nImportEls == 0);
+    mpi::globalMax(createEmptyPartition);
+
+    if (createEmptyPartition > 0)
+      err = ZOLTAN_FATAL;
+
     if (err == ZOLTAN_OK && changes != 0) {   
       if (nImportEls > 0) {
 	for (int i = 0; i < nImportEls; i++) {