What is MPI_Comm_create

MPI library

MPI (Message Passing Interface) is a library that allows you to write parallel programs in C or Fortran77. The library uses commonly available operating system services to create parallel processes and exchange information among these processes.

MPI_Comm_ceate_errhandler

This method creates a communicator error handler.

Syntax

int MPI_Comm_create_errhandler(MPI_Comm_errhandler_function *comm_errhandler_fn, MPI_Errhandler *errhandler)

Parameters

comm_errhandler_function is a user-defined error handling function of the form void MPI_Comm_errhandler_function(MPI_Comm *comm, int *rc);.
errorhandler is an output parameter representing the MPI error handler.

Return value

The function returns an error if it is unsuccessful. The error aborts the MPI job by default.
In case of success, it returns MPI_SUCCESS - the value returned upon successful termination of any MPI routine.
In case of an invalid communicator provided in the function’s argument, MPI_ERR_COM is returned.
MPI_ERR_OTHER is returned if there is some other error. You can use MPI_Error_string to get more information about this error code.

Example

The example below demonstrates how we can use the MPI_Comm_create_errhandler method:

#include "mpi.h"
#include <stdio.h>
static int calls = 0;
static int errs = 0;
static MPI_Comm mycomm;
void userDefinedErrHandler( MPI_Comm *comm, int *err, ... )
{
    if (*err != MPI_ERR_OTHER) {
      errs++;
      printf( "Unexpected error code\n" );fflush(stdout);
    }
    if (*comm != mycomm) {
      errs++;
      printf( "Unexpected communicator\n" );fflush(stdout);
    }
    calls++;
    return;
}
int main( int argc, char *argv[] )
{
  MPI_Comm comm;
  MPI_Errhandler newHandler;
  MPI_Init( &argc, &argv );
  comm = MPI_COMM_WORLD;
  mycomm = comm;
  MPI_Comm_create_errhandler( userDefinedErrHandler, &newHandler );
  return 0;
}