The results of the code listed below are very strange.
Using a single core the degrees of freedom is:
mpirun -np 1 ./untitled
Cycle 0:
Number of active cells: 24
Number of degrees of freedom: 889
=====================================
Cycle 1:
Number of active cells: 192
Number of degrees of freedom: 6097
=====================================
Cycle 2:
Number of active cells: 1536
Number of degrees of freedom: 45025
=====================================
Cycle 3:
Number of active cells: 12288
Number of degrees of freedom: 345793
=====================================
But, when using MPI with 8 nodes, it is:
mpirun -np 8 ./untitled
Cycle 0:
Number of active cells: 24
Number of degrees of freedom: 889
=====================================
Cycle 1:
Number of active cells: 192
Number of degrees of freedom: 6097
=====================================
Cycle 2:
Number of active cells: 1536
Number of degrees of freedom: 45240
=====================================
Cycle 3:
Number of active cells: 12288
Number of degrees of freedom: 347340
=====================================
As you can see after "Cycle 2", the number of degrees of freedom is
different. What is wrong in this code?
Test code is:
#include <iostream>
#include <deal.II/distributed/tria.h>
#include <deal.II/dofs/dof_handler.h>
#include <deal.II/fe/fe_q.h>
#include <deal.II/base/mpi.h>
#include <deal.II/base/utilities.h>
#include <deal.II/base/conditional_ostream.h>
#include <deal.II/base/index_set.h>
using namespace dealii;
class Problem
{
public:
Problem();
~Problem();
void run();
private:
MPI_Comm mpi_communicator;
parallel::distributed::Triangulation<3> triangulation;
DoFHandler<3> dof_handler;
FE_Q<3> fe;
ConditionalOStream pcout;
void make_domain_quater_crack();
};
Problem::Problem() :
mpi_communicator (MPI_COMM_WORLD),
triangulation (mpi_communicator,
typename Triangulation<3>::MeshSmoothing
(Triangulation<3>::smoothing_on_refinement |
Triangulation<3>::smoothing_on_coarsening)),
dof_handler(triangulation),
fe(3),
pcout (std::cout,
(Utilities::MPI::this_mpi_process(mpi_communicator) == 0))
{}
Problem::~Problem()
{
dof_handler.clear();
}
void Problem::make_domain_quater_crack() {
std::vector<Point<3>> vertices ={
{0.0,0.0,0.0},
{1.0,0.0,0.0},
{2.0,0.0,0.0},
{0.0,0.0,1.0},
{1.0,0.0,1.0},
{2.0,0.0,1.0},
{0.0,1.0,0.0},
{0.0,2.0,0.0},
{0.0,1.0,1.0},
{0.0,2.0,1.0},
{1.0,1.0,0.0},
{2.0,2.0,0.0},
{1.0,1.0,1.0},
{2.0,2.0,1.0},
};
const std::vector<std::array<int, GeometryInfo<3>::vertices_per_cell>>
cell_vertices = {
{0,1,6,10,3,4,8,12},
{1,2,10,11,4,5,12,13},
{10,11,6,7,12,13,8,9},
};
const unsigned int n_cells = cell_vertices.size();
std::vector<CellData<3>> cells(n_cells, CellData<3>());
for (unsigned int i = 0; i < n_cells; ++i)
{
for (unsigned int j = 0; j < GeometryInfo<3>::vertices_per_cell;
++j)
cells[i].vertices[j] = cell_vertices[i][j];
cells[i].material_id = 0;
}
triangulation.create_triangulation(vertices, cells, SubCellData());
}
void Problem::run() {
make_domain_quater_crack();
unsigned int max_cycle=4;
for (unsigned int cycle(0); cycle<max_cycle; ++cycle){
triangulation.refine_global(1);
dof_handler.distribute_dofs (fe);
if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0) {
const unsigned int n_active_cells =
triangulation.n_global_active_cells();
const unsigned int n_dofs = dof_handler.n_dofs();
pcout << "Cycle " << cycle << ':'
<< std::endl
<< " Number of active cells: "
<< n_active_cells
<< std::endl
<< " Number of degrees of freedom: "
<< n_dofs
<< std::endl;
}
pcout << "=====================================" << std::endl;
pcout << std::endl;
}
}
int main(int argc, char *argv[])
{
try
{
Utilities::MPI::MPI_InitFinalize mpi_initialization(argc, argv, 1);
Problem test;
test.run ();
}
catch (std::exception &exc)
{
std::cerr << std::endl << std::endl
<< "----------------------------------------------------"
<< std::endl;
std::cerr << "Exception on processing: " << std::endl
<< exc.what() << std::endl
<< "Aborting!" << std::endl
<< "----------------------------------------------------"
<< std::endl;
return 1;
}
catch (...)
{
std::cerr << std::endl << std::endl
<< "----------------------------------------------------"
<< std::endl;
std::cerr << "Unknown exception!" << std::endl
<< "Aborting!" << std::endl
<< "----------------------------------------------------"
<< std::endl;
return 1;
}
return 0;
}
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