From: heister <heister@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Wed, 27 Mar 2013 03:31:17 +0000 (+0000)
Subject: make MPI_InitFinalize initialize PETSc even if not using MPI
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8d26f335aa8c3719b933cdec8036348ad2cea3c1;p=dealii-svn.git

make MPI_InitFinalize initialize PETSc even if not using MPI

git-svn-id: https://svn.dealii.org/trunk@29052 0785d39b-7218-0410-832d-ea1e28bc413d
---

diff --git a/deal.II/doc/news/changes.h b/deal.II/doc/news/changes.h
index 4115f219e3..72a1f90da4 100644
--- a/deal.II/doc/news/changes.h
+++ b/deal.II/doc/news/changes.h
@@ -80,6 +80,13 @@ this function.
 
 <ol>
 
+<li> New: MPI_InitFinalize can also initialize PETSc/Slepc when
+not compiling with MPI. This is now the preferred way to initialize
+MPI/PETSc/Slepc in all cases.
+<br>
+(Timo Heister, 2013/3/26)
+</li>
+
 <li> Added/fixed: IterativeInverse::vmult() can now handle vectors
 using a different number type than the matrix type. As usual, the
 number types must be compatible. Addtitionally, the initial guess is
diff --git a/deal.II/source/base/mpi.cc b/deal.II/source/base/mpi.cc
index edc8c03da9..4a1c99c7bb 100644
--- a/deal.II/source/base/mpi.cc
+++ b/deal.II/source/base/mpi.cc
@@ -338,9 +338,6 @@ namespace Utilities
               ExcMessage ("You can only create a single object of this class "
                           "in a program since it initializes the MPI system."));
 
-#ifdef DEAL_II_WITH_MPI
-      // if we have PETSc, we will initialize it and let it handle MPI.
-      // Otherwise, we will do it.
 #ifdef DEAL_II_WITH_PETSC
 #  ifdef DEAL_II_WITH_SLEPC
       // Initialise SLEPc (with PETSc):
@@ -350,6 +347,9 @@ namespace Utilities
       PetscInitialize(&argc, &argv, PETSC_NULL, PETSC_NULL);
 #  endif
 #else
+#  ifdef DEAL_II_WITH_MPI
+      // if we have PETSc, we will initialize it and let it handle MPI.
+      // Otherwise, we will do it.
       int MPI_has_been_started = 0;
       MPI_Initialized(&MPI_has_been_started);
       AssertThrow (MPI_has_been_started == 0,
@@ -359,13 +359,13 @@ namespace Utilities
       mpi_err = MPI_Init (&argc, &argv);
       AssertThrow (mpi_err == 0,
                    ExcMessage ("MPI could not be initialized."));
-#endif
-#else
+#  else
       // make sure the compiler doesn't warn
       // about these variables
       (void)argc;
       (void)argv;
       (void)owns_mpi;
+#  endif
 #endif
 
       constructor_has_already_run = true;
@@ -377,26 +377,26 @@ namespace Utilities
 
     MPI_InitFinalize::~MPI_InitFinalize()
     {
-#ifdef DEAL_II_WITH_MPI
-
-      // make memory pool release all MPI-based vectors that are no
+      // make memory pool release all PETSc/Trilinos/MPI-based vectors that are no
       // longer used at this point. this is relevant because the
       // static object destructors run for these vectors at the end of
       // the program would run after MPI_Finalize is called, leading
       // to errors
+
+#ifdef DEAL_II_WITH_MPI
+      // Start with Trilinos (need to do this before finalizing PETSc because it finalizes MPI.
+      // Delete vectors from the pools:
 #  if defined(DEAL_II_WITH_TRILINOS)
       GrowingVectorMemory<TrilinosWrappers::MPI::Vector>
       ::release_unused_memory ();
       GrowingVectorMemory<TrilinosWrappers::MPI::BlockVector>
       ::release_unused_memory ();
 #  endif
+#endif
 
-      // Same for PETSc. only do this if PETSc hasn't been
-      // terminated yet since PETSc deletes all vectors that
-      // have been allocated but not freed at the time of
-      // calling PETScFinalize. running the calls below after
-      // PetscFinalize has already been called will therefore
-      // yield errors of double deallocations
+
+      // Now deal with PETSc (with or without MPI). Only delete the vectors if finalize hasn't
+      // been called yet, otherwise this will lead to errors.
 #ifdef DEAL_II_WITH_PETSC
       if ((PetscInitializeCalled == PETSC_TRUE)
           &&
@@ -418,10 +418,14 @@ namespace Utilities
           // or just end PETSc.
           PetscFinalize();
 #  endif
-        }
-#else
+	}
+#endif	  
 
 
+      // only MPI_Finalize if we are running with MPI and we are not using PETSc
+      // (otherwise we called it above already):
+#ifdef DEAL_II_WITH_MPI
+#ifndef DEAL_II_WITH_PETSC
       int mpi_err = 0;
 
       int MPI_has_been_started = 0;