How to use and interpret MPI-IO Error codes? - mpi

Question

#include <stdio.h>
#include <iostream>
#include <Windows.h>
#include <C:\Program Files\Microsoft MPI\Inc\mpi.h>
using namespace std;
#define BUFSIZE 128
int main (int argc, char *argv[])
{
int err;
int rank;
int size;
double start_time = 0.0;
double end_time;
MPI_Comm comm = MPI_COMM_WORLD;
MPI_File file;
char cbuf[BUFSIZE];
for(int i = 0; i < BUFSIZE; i++)
{
cbuf[i] = 'a' + i;
}
if(err = MPI_Init(&argc, &argv))
{
printf("%s \n", "Error! MPI is halted!");
MPI_Abort(comm, err);
}
MPI_Comm_size(comm, &size);
MPI_Comm_rank(comm, &rank);
if(rank == 0)
{
start_time = MPI_Wtime();
}
err = MPI_File_open(comm, "testfile", MPI_MODE_CREATE | MPI_MODE_RDWR, MPI_INFO_NULL, &file);
if(err != MPI_SUCCESS)
{
printf("Error %d! Can't open the file!\n", err);
MPI_Abort(comm, err);
return EXIT_FAILURE;
}
err = MPI_File_set_view(file, (MPI_Offset) (rank * BUFSIZE * sizeof(char)), MPI_CHAR, MPI_CHAR, "native", MPI_INFO_NULL);
if(err != MPI_SUCCESS)
{
printf("%s \n", "Error! Can't set the view!");
MPI_Abort(comm, err);
return EXIT_FAILURE;
}
err = MPI_File_write(file, cbuf, BUFSIZE, MPI_CHAR, MPI_STATUSES_IGNORE);
if(err != MPI_SUCCESS)
{
printf("%s \n", "Error! Problems with writing!");
MPI_Abort(comm, err);
return EXIT_FAILURE;
}
MPI_File_close(&file);
if(rank == 0)
{
end_time = MPI_Wtime();
printf("Time elapsed : %f seconds", (end_time - start_time) * 1000);
}
MPI_Finalize();
return EXIT_SUCCESS;
}
I'm trying to write some symbols to a file with MPI. When I do that, I get an errorcode of 288 and the file can't be opened. I used command line: mpiexec -n 10 myapp.exe. I was searching for the errorcode but didn't find anything at all.

Answer 1

Go one step further. Your error code doesn't mean anything by itself. But, you can feed that code to MPI_Error_string and get something more human readable. I have this function in every MPI-IO code I write:
static void handle_error(int errcode, char *str)
{
char msg[MPI_MAX_ERROR_STRING];
int resultlen;
MPI_Error_string(errcode, msg, &resultlen);
fprintf(stderr, "%s: %s\n", str, msg);
MPI_Abort(MPI_COMM_WORLD, 1);
}
And then define this macro:
#define MPI_CHECK(fn) { int errcode; errcode = (fn);\
if (errcode != MPI_SUCCESS) handle_error (errcode, #fn ); }
So I can call routines like this:
CHECK(MPI_File_open(comm, "testfile",
MPI_MODE_CREATE | MPI_MODE_RDWR, MPI_INFO_NULL, &file) );