Mesio is a highly-parallel loader and converter of external unstructured meshes databases. It is composed of several commonly used algorithms that together provide a robust solution for the pre/post-processing phase of solving large-scale engineering problems (pdf). With mesio a user is able to use the same sequential database file with an arbitrary number of MPI processes. It allows engineers to use their favorite tools for creation of numerical models without any penalty for a parallel run.
Mesio is composed from (i) the mesh builder that is able to reconstruct an unstructured mesh from randomly scattered data across parallel processes in a distributed memory of an HPC machine without gathering data into a single node and (ii) lightweight parallel parsers of given mesh databases. Hence, the usage is not limited to any particular format -- only a simple parallel parser has to be implemented for a new format. Currently, the following parsers are implemented:
An output database stored by mesio is also in a sequential form for simple by a favorite visualization tool. The following format are available:
Mesio functionality is provided to other researchers by API.
In the current version the modules can be compiled and executed on Linux operating systems only. Some functionality requires third party libraries that should be installed in the system before the installation process. Currently available wrappers are the followings:
For compilation Python-based framework Waf is used. The compilation process has two phases: configuration and compilation. The former configures persistent data and checks available headers and libraries. The latter builds the library. It is mandatory to re-run the configuration process after any environment change. The following commands build all modules if require libraries are available:
$ ./waf configure
$ ./wafThe compilation process builds all libraries and executable tools into the build directory. This directory should be added to LD_LIBRARY_PATH and PATH environment variables. Then it is possible to run mesio by the following command:
$ mpirun -n $N mesio -i INPUT_FORMAT -p INPUT_PATH -o OUTPUT_FORMAT -s STORE_PATHwhere N is the number of MPI processes.
Before running the library, the following variables should be set according to the number of CPU cores per compute node (nCores) and number of MPI processes processed per node (PPN):
Our parallel loader can be utilized by third party software by provided C API. The interface is available via the mesio.h header in the include directory and the libmesioapi library. An example of calling the library can be found in src/api/api.mesio.cpp. The code below shows how the loader should be called. Once the method MESIOLoad is finished an input database is loaded. Then, one can use provided functions to return mesh data stored in internal structures. The code shows requesting of nodes and elements only. For the full API description see the provided example and our wiki (the wiki also contains the description of how to implement a simple parallel parser).
#include "mesio.h"
int main(int argc, char **argv)
{
MPI_Init(&argc, &argv);
MESIO mesio;
int verbose = 2;
int domains = 0;
MESIOInit(MPI_COMM_WORLD, verbose);
MESIOLoad(&mesio, MESIO_ANSYS, "path_to_file", MESIO_PARMETIS, domains);
{ // GET NODES
MESIOInt nhalo, offset, size, totalSize;
MESIOInt *ids, *position;
MESIOReal *coordinates;
MESIONodes(mesio, &nhalo, &offset, &size, &totalSize, &ids, &position, &coordinates);
}
{ // GET ELEMENTS
MESIOInt offset, size, totalSize;
MESIOInt *type, *enodesDist, *enodesData;
MESIOElements(mesio, &offset, &size, &totalSize, &type, &enodesDist, &enodesData);
}
MESIOFinalize();
MPI_Finalize();
return 0;
}See the LICENSE file at the root directory.
This work was supported by