segmentation fault

[Liu, Jaln]

Hi,
Can anybody help me with the following problem? I appreciate it.

when I run the program in a 16 nodes cluster, I met the segmentation fault error

the code is downloaded from pnetcdf website and is modified a little:
source:
#include <stdlib.h>
#include <mpi.h>
#include <pnetcdf.h>
#include <stdio.h>

static void handle_error(int status)
{
    fprintf(stderr, "%s\n", ncmpi_strerror(status));
    exit(-1);
}


int main(int argc, char **argv) {

    int rank, nprocs;
    int ret, varid,ncfile, ndims, nvars, ngatts, unlimited;
    int var_ndims, var_natts;;
    MPI_Offset *dim_sizes, var_size;
    MPI_Offset *start, *count;

    char varname[NC_MAX_NAME+1];
    int dimids[NC_MAX_VAR_DIMS];
    nc_type type;

    int i, j;

    int *data;

    MPI_Init(&argc, &argv);

    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
    char * FILE_NAME="nfs:output.nc";
    ret = ncmpi_open(MPI_COMM_WORLD, FILE_NAME, NC_NOWRITE, MPI_INFO_NULL,
            &ncfile);
    if (ret != NC_NOERR) handle_error(ret);


    ret = ncmpi_inq(ncfile, &ndims, &nvars, &ngatts, &unlimited);
    if (ret != NC_NOERR) handle_error(ret);

    dim_sizes = calloc(ndims, sizeof(MPI_Offset));

    for(i=0; i<ndims; i++)  {
        ret = ncmpi_inq_dimlen(ncfile, i, &(dim_sizes[i]) );
        if (ret != NC_NOERR) handle_error(ret);
    }

    for(i=0; i<nvars; i++) {
       ret = ncmpi_inq_var(ncfile, i, varname, &type, &var_ndims, dimids,
                &var_natts);
        if (ret != NC_NOERR) handle_error(ret);

        start = calloc(var_ndims, sizeof(MPI_Offset));
        count = calloc(var_ndims, sizeof(MPI_Offset));

        start[0] = (dim_sizes[dimids[0]]/nprocs)*rank;
        count[0] = (dim_sizes[dimids[0]]/nprocs);
        var_size = count[0];

        for (j=1; j<var_ndims; j++) {
            start[j] = 0;
            count[j] = dimids[j];
            var_size *= count[j];
        }

        switch(type) {
            case NC_INT:
                data = calloc(var_size, sizeof(int));

                ret = ncmpi_get_vara_int_all(ncfile, i, start, count, data);

                if (ret != NC_NOERR) handle_error(ret);

                break;
            default:
                /* we can do this for all the known netcdf types but this
                 * example is already getting too long  */
                fprintf(stderr, "unsupported NetCDF type \n");
        }

        free(start);
        free(count);
        if (data != NULL) free(data);

}
    ret = ncmpi_close(ncfile);
    if (ret != NC_NOERR) handle_error(ret);

    MPI_Finalize();
    return 0;
}

the file output.nc:
netcdf output {
dimensions:
    d1 = 16 ;
variables:
    int v1(d1) ;
    int v2(d1) ;

// global attributes:
        :string = "Hello World\n",
            "" ;
data:

 v1 = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 ;

 v2 = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 ;
}

Compiling command:
mpicc -o preadsegfault preadsegfault.c
Run the program:
mpirun -np 4 ./preadsegfault


Best Regards,
Jialin Liu, Ph.D student.
Computer Science Department
Texas Tech University
Phone: 806.742.3513(x241)
Office:Engineer Center 304
http://myweb.ttu.edu/jialliu/
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