Optional comm kwarg

Author: pbrubeck

firedrake/cython/dmcommon.pyx

@@ -3820,7 +3820,7 @@ def submesh_create(PETSc.DM dm,
                    label_name,
                    PetscInt label_value,
                    PetscBool ignore_label_halo,
-                   PETSc.Comm comm):
+                   comm=None):
     """Create submesh.
 
     Parameters
@@ -3835,7 +3835,7 @@ def submesh_create(PETSc.DM dm,
         Value in the label
     ignore_label_halo : bool
         If labeled points in the halo are ignored.
-    comm: PETSc.Comm
+    comm : PETSc.Comm | None
         An optional sub-communicator to define the submesh.
 
     """

firedrake/mg/mesh.py

@@ -136,7 +136,7 @@ def MeshHierarchy(mesh, refinement_levels,
     #    This is algorithmically guaranteed.
     dm_cell_type, = mesh.dm_cell_types
     tdim = mesh.topology_dm.getDimension()
-    cdm = dmcommon.submesh_create(mesh.topology_dm, tdim, "celltype", dm_cell_type, True, None)
+    cdm = dmcommon.submesh_create(mesh.topology_dm, tdim, "celltype", dm_cell_type, True)
     cdm.removeLabel("pyop2_core")
     cdm.removeLabel("pyop2_owned")
     cdm.removeLabel("pyop2_ghost")

firedrake/preconditioners/bddc.py

@@ -197,7 +197,7 @@ def local_mesh(mesh):
             return cache[key]
         except KeyError:
             if mesh.comm.size > 1:
-                submesh = Submesh(mesh, mesh.topological_dimension, 0, ignore_halo=True, comm=PETSc.COMM_SELF)
+                submesh = Submesh(mesh, mesh.topological_dimension, None, ignore_halo=True, comm=PETSc.COMM_SELF, reorder=False)
             else:
                 submesh = None
             return cache.setdefault(key, submesh)