Bugfix: localParallel and comms allocation per GGI pair

src/foam/meshes/polyMesh/polyPatches/constraint/ggi/ggiPolyPatch.C

@@ -65,16 +65,11 @@ bool Foam::ggiPolyPatch::active() const
 
     if (shadow.active() && zone.active())
     {
-        if
-        (
-            !Pstream::parRun()
-         && size() != boundaryMesh().mesh().faceZones()[zone.index()].size()
-        )
+        if (!Pstream::parRun() && !localParallel())
         {
             // Patch is present in serial run, but zone is not the same size
             // Probably doing decomposition and reconstruction
             // HJ, 14/Sep/2016
-
             return false;
         }
 
@@ -325,19 +320,6 @@ void Foam::ggiPolyPatch::calcLocalParallel() const
     localParallelPtr_ = new bool(false);
     bool& emptyOrComplete = *localParallelPtr_;
 
-    // If running in serial, all GGIs are expanded to zone size.
-    // This happens on decomposition and reconstruction where
-    // size and shadow size may be zero, but zone size may not
-    // HJ, 1/Jun/2011
-    if (!Pstream::parRun())
-    {
-        emptyOrComplete = false;
-    }
-    else
-    {
-        // Check that patch size is greater than the zone size.
-        // This is an indication of the error where the face zone is not global
-        // in a parallel run.  HJ, 9/Nov/2014
     if (size() > zone().size())
     {
         FatalErrorIn("void ggiPolyPatch::calcLocalParallel() const")
@@ -349,25 +331,35 @@ void Foam::ggiPolyPatch::calcLocalParallel() const
     }
 
     // Calculate localisation on master and shadow
+    if ((size() == 0 && shadow().size() == 0))
+    {
+        // No ggi on this processor
+        emptyOrComplete = true;
+    }
+    else if (!zone().empty() || !shadow().zone().empty())
+    {
+        // GGI present on the processor and complete for both
         emptyOrComplete =
         (
             zone().size() == size()
          && shadow().zone().size() == shadow().size()
-            )
-         || (size() == 0 && shadow().size() == 0);
-
-        reduce(emptyOrComplete, andOp<bool>());
-    }
-
-    if (emptyOrComplete)
-    {
-        comm_ = boundaryMesh().mesh().comm();
+        );
     }
     else
+    {
+        // Master and shadow on different processors
+        emptyOrComplete = false;
+    }
+
+    reduce(emptyOrComplete, andOp<bool>());
+
+    // Note: only master allocates the comm_
+    // HJ, 20/Sep/2016
+    if (!emptyOrComplete && Pstream::parRun() && master())
     {
         // Count how many patch faces exist on each processor
         labelList nFacesPerProc(Pstream::nProcs(), 0);
-        nFacesPerProc[Pstream::myProcNo()] = size();
+        nFacesPerProc[Pstream::myProcNo()] = size() + shadow().size();
 
         Pstream::gatherList(nFacesPerProc);
         Pstream::scatterList(nFacesPerProc);
@@ -397,6 +389,10 @@ void Foam::ggiPolyPatch::calcLocalParallel() const
             << " with " << ggiCommProcs << ": " << comm_
             << endl;
     }
+    else
+    {
+        comm_ = boundaryMesh().mesh().comm();
+    }
 
     if (debug && Pstream::parRun())
     {
@@ -844,13 +840,20 @@ Foam::label Foam::ggiPolyPatch::comm() const
     //HJ, Testing.  Use optimised comm or a local one
 
     // Note: comm is calculated with localParallel and will use the
-    // localParallelPtr_ for signalling.  HJ, 10/Sep2016
+    // localParallelPtr_ for signalling.  HJ, 10/Sep/2016
+    if (master())
+    {
         if (!localParallelPtr_)
         {
             calcLocalParallel();
         }
 
         return comm_;
+    }
+    else
+    {
+        return shadow().comm();
+    }
 
 //     return boundaryMesh().mesh().comm();
 }

src/foam/meshes/polyMesh/polyPatches/constraint/ggi/ggiPolyPatch.H

@@ -106,6 +106,7 @@ class ggiPolyPatch
             mutable bool* localParallelPtr_;
 
             //- Communicator to use for parallel communication
+            //  Note: only master side allocates the comm
             mutable label comm_;
 
             //- Message tag used for sending