From ed17d3c405f16c5ff1fa945962afd0525fe74b4e Mon Sep 17 00:00:00 2001
From: Henry Weller <http://cfd.direct>
Date: Sun, 26 May 2024 14:27:06 +0100
Subject: [PATCH] parMetis: Added test for points on all processors

Unfortunately ParMETIS does not support redistribution of empty processors.
---
 src/parallel/decompose/parMetis/parMetis.C | 23 ++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/parallel/decompose/parMetis/parMetis.C b/src/parallel/decompose/parMetis/parMetis.C
index b12b0329aa..9fd77d68e0 100644
--- a/src/parallel/decompose/parMetis/parMetis.C
+++ b/src/parallel/decompose/parMetis/parMetis.C
@@ -308,6 +308,14 @@ Foam::labelList Foam::decompositionMethods::parMetis::decompose
             << exit(FatalError);
     }
 
+    if (Pstream::parRun() && !points.size())
+    {
+        Pout<< "No points on processor " << Pstream::myProcNo() << nl
+            << "    ParMETIS cannot redistribute without points"
+               "on all processors." << endl;
+        FatalErrorInFunction << exit(FatalError);
+    }
+
     // Make Metis CSR (Compressed Storage Format) storage
     //   adjncy      : contains neighbours (= edges in graph)
     //   xadj(celli) : start of information in adjncy for celli
@@ -352,6 +360,13 @@ Foam::labelList Foam::decompositionMethods::parMetis::decompose
             << exit(FatalError);
     }
 
+    if (Pstream::parRun() && !regionPoints.size())
+    {
+        Pout<< "No points on processor " << Pstream::myProcNo() << nl
+            << "    ParMETIS cannot redistribute without points"
+               "on all processors." << endl;
+        FatalErrorInFunction << exit(FatalError);
+    }
 
     // Make Metis CSR (Compressed Storage Format) storage
     //   adjncy      : contains neighbours (= edges in graph)
@@ -405,6 +420,14 @@ Foam::labelList Foam::decompositionMethods::parMetis::decompose
             << ")." << exit(FatalError);
     }
 
+    if (Pstream::parRun() && !cellCentres.size())
+    {
+        Pout<< "No points on processor " << Pstream::myProcNo() << nl
+            << "    ParMETIS cannot redistribute without points"
+               "on all processors." << endl;
+        FatalErrorInFunction << exit(FatalError);
+    }
+
     // Make Metis Distributed CSR (Compressed Storage Format) storage
     //   adjncy      : contains neighbours (= edges in graph)
     //   xadj(celli) : start of information in adjncy for celli