From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Fri, 7 May 2021 21:18:25 +0000 (+0200)
Subject: p:f:Tria: Fix bug when a process does not own cells on a level
X-Git-Tag: v9.3.0-rc1~116^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2071274927364190b07fc3bc6a6da9e2c5a6be86;p=dealii.git

p:f:Tria: Fix bug when a process does not own cells on a level
---

diff --git a/source/distributed/fully_distributed_tria.cc b/source/distributed/fully_distributed_tria.cc
index 802d8b5996..ca160614c8 100644
--- a/source/distributed/fully_distributed_tria.cc
+++ b/source/distributed/fully_distributed_tria.cc
@@ -184,7 +184,9 @@ namespace parallel
             }
 
           // 4b) set actual (level_)subdomain_ids
-          for (unsigned int level = 0; level < cell_infos.size(); ++level)
+          for (unsigned int level = 0;
+               level < cell_infos.size() && !cell_infos[level].empty();
+               ++level)
             {
               auto cell      = this->begin(level);
               auto cell_info = cell_infos[level].begin();
diff --git a/source/grid/tria.cc b/source/grid/tria.cc
index 2f737a0bb4..d7900e35c1 100644
--- a/source/grid/tria.cc
+++ b/source/grid/tria.cc
@@ -10660,8 +10660,12 @@ Triangulation<dim, spacedim>::create_triangulation(
           return a_id < b_id;
       });
 
-  // 2) create all levels via a sequence of refinements
-  for (unsigned int level = 0; level < cell_infos.size(); ++level)
+  // 2) create all levels via a sequence of refinements. note that
+  //    we must make sure that we actually have cells on this level,
+  //    which is not clear in a parallel context for some processes
+  for (unsigned int level = 0;
+       level < cell_infos.size() && !cell_infos[level].empty();
+       ++level)
     {
       // a) set manifold ids here (because new vertices have to be
       //    positioned correctly during each refinement step)
@@ -10714,7 +10718,9 @@ Triangulation<dim, spacedim>::create_triangulation(
     }
 
   // 3) set boundary ids
-  for (unsigned int level = 0; level < cell_infos.size(); ++level)
+  for (unsigned int level = 0;
+       level < cell_infos.size() && !cell_infos[level].empty();
+       ++level)
     {
       auto cell      = this->begin(level);
       auto cell_info = cell_infos[level].begin();