MPI causes breakpoint - c++

Question

I've made an application that counts number of characters using MS MPI, but it causes 4 breakpoints at:
MPI_File_get_size, MPI_File_set_view, MPI_File_read and again at MPI_File_get_size(fh, &size).
Do you know what may cause them? Full code below:
#include "stdafx.h"
#include "mpi.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stack>
using namespace std;
int main(int argc, char *argv[])
{
int numprocs, rank, buffer[100];
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
MPI_Status status;
MPI_File fh;
MPI_Offset size;
int char_number;
const char plik[10] = "file.txt";
MPI_File_open(MPI_COMM_WORLD, plik, MPI_MODE_RDONLY, MPI_INFO_NULL, &fh);
MPI_File_get_size(fh, &size);
MPI_File_set_view(fh, rank*(size / numprocs), MPI_CHAR, MPI_CHAR, "native", MPI_INFO_NULL);
MPI_File_read(fh, &buffer[100], 1, MPI_CHAR, &status);
char_number = MPI_File_get_size(fh, &size);
MPI_File_close(&fh);
if (rank == 0) {
for (int i = 0; i < numprocs; i++) {
MPI_Recv(&char_number, i, MPI_INT, 0, 1, MPI_COMM_WORLD, &status);
}
}
else {
MPI_Send(&char_number, 0, MPI_INT, 0, 3, MPI_COMM_WORLD);
}
MPI_Finalize();
return 0;
}
EDIT: Got rid of breakpoints, but not receiving any output now:
#include "stdafx.h"
#include "mpi.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stack>
using namespace std;
int main(int argc, char *argv[])
{
int numprocs, rank;
char buffer[100] = { 0 };
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
MPI_Status status;
MPI_File fh;
MPI_Offset size;
int char_number;
const char plik[10] = "file.txt";
MPI_File_open(MPI_COMM_WORLD, plik, MPI_MODE_RDONLY, MPI_INFO_NULL, &fh);
MPI_File_get_size(fh, &size);
MPI_File_set_view(fh, rank*(size / numprocs), MPI_CHAR, MPI_CHAR, "native", MPI_INFO_NULL);
MPI_File_read(fh, buffer, (size/numprocs), MPI_CHAR, &status);
char_number = MPI_File_get_size(fh, &size);
MPI_File_close(&fh);
if (rank == 0) {
for (int i = 0; i < numprocs; i++) {
MPI_Recv(&char_number, i, MPI_INT, 0, 1, MPI_COMM_WORLD, &status);
}
cout << "There is: " << char_number << " characters in file.txt";
}
else {
MPI_Send(&char_number, 0, MPI_INT, 0, 3, MPI_COMM_WORLD);
}
MPI_Finalize();
return 0;
}

Answer 1

It might be your breakpoints are still on the list:
I deleted a breakpoint, but I continue to hit it when I start
debugging again
If you deleted a breakpoint while debugging, in some
cases you may hit the breakpoint again the next time you start
debugging. To stop hitting this breakpoint, make sure all the
instances of the breakpoint are removed from the Breakpoints window.
Source: https://msdn.microsoft.com/en-us/library/5557y8b4.aspx
I remember similar situation in the past with some executables. Removing breakpoint from the source code was not enough.
It also might be that you are trying to access non-existing file.
It also might be that your code is not quite OK.
#include "mpi.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stack>
using namespace std;
int main(int argc, char *argv[])
{
int numprocs, rank;
// buffer will keep input data
char buffer[100] = { 0 };
// initialization of MPI world
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
MPI_Status status;
MPI_File fh;
MPI_Offset size;
int char_number;
// name of the file with data
const char plik[10] = "file.txt";
MPI_File_open(MPI_COMM_WORLD, plik, MPI_MODE_RDONLY, MPI_INFO_NULL, &fh);
MPI_File_get_size(fh, &size);
// we have to be careful here
// in this sample we have strong assumption that size of data
// divides without the reminder by number of processors!
MPI_File_set_view(fh, rank*(size / numprocs), MPI_CHAR, MPI_CHAR, "native", MPI_INFO_NULL);
MPI_File_read(fh, buffer, (size/numprocs), MPI_CHAR, &status);
char_number = MPI_File_get_size(fh, &size);
MPI_File_close(&fh);
printf("My rank: %d - my data: %s\n", rank, buffer);
if (rank == 0) {
for (int i = 1; i < numprocs; i++) {
MPI_Recv(&buffer[i*(size / numprocs)], (size/numprocs), MPI_CHAR, i, 0, MPI_COMM_WORLD, &status);
}
printf("I have collected data: %s\n",buffer);
}
else {
MPI_Send(&buffer[0], rank*(size / numprocs), MPI_CHAR, 0, 0, MPI_COMM_WORLD);
}
MPI_Finalize();
return 0;
}
For input file
> cat file.txt
abcdefgh
works as expected:
> mpirun -np 2 ./simple2
My rank: 0 - my data: abcd
I have collected data: abcdefgh
My rank: 1 - my data: efgh
Question is, whether this is what you are looking for.