[MPICH] Help With I/O

[Erich Peterson]

Hi all, I'm trying to write this little routine which is part of my graduate project. What I'm trying to do is pass a vector of bools in to the QueryData method. In that method I split the vector up into equal parts among the number of processes, have each process open a datafile which as 20 byte records (no new lines), read that record from the file if the vector they are checking has "true" (basically if vector[0] = true, it means grab the first record of the file), and lastly, it should output that record into a new file. I have been able to determine it is messing up on the for-loop. The error is:
 
[Student at cluster1 erich_test_area]$ mpiexec -n 3 /mnt/pvfs2/acxiom/erich_test_area/RecordRetrievalterminate called after throwing an instance of 'MPI::Exception'terminate called after throwing an instance of 'MPI::Exception'terminate called after throwing an instance of 'MPI::Exception'rank 0 in job 1  cluster1_33602   caused collective abort of all ranks  exit status of rank 0: killed by signal 6 If someone could please tell me or edit the code if they see what is wrong. Thanks! Main.cpp:
#include "RecordRetrieval.h"#include <vector.h>
int main(){   vector<bool> vec;
   vec.push_back(true);   vec.push_back(false);   vec.push_back(true);   vec.push_back(false);   vec.push_back(true);   vec.push_back(false);
   RecordRetrieval rec;
   rec.QueryData(vec, "test.dat");
   return 0;}
RecordRetrieval.cpp:
 
#include "RecordRetrieval.h"#include "mpi.h"#include "time.h"#include "iostream.h"
void RecordRetrieval::QueryData(vector<bool> unencoded_vector, char * filename){    int num_processes;    int num_vector_elements;    float num_elements_per_rank;    int local_start_position;    int local_end_position;    char * buf;    int my_rank;
    MPI::File input_file;    MPI::Status input_file_status;
    MPI::File output_file;    MPI::Status output_file_status;    //MPI::Offset filesize;
    char output_filename[30];    size_t i;    struct tm tim;    time_t now;    now = time(NULL);    tim = *(localtime(&now));    i = strftime(output_filename, 30, "%m_%d_%Y_%H_%M_%S", &tim);
    /* Let the system do what it needs to start up MPI */    MPI::Init();
    /* Get my process rank */    my_rank = MPI::COMM_WORLD.Get_rank();
    /* Find out how many processes are being used */    num_processes = MPI::COMM_WORLD.Get_size();
    num_vector_elements = unencoded_vector.size();
    num_elements_per_rank = num_vector_elements / num_processes;
    local_start_position = my_rank * (int)num_elements_per_rank;
    if(my_rank == num_processes - 1)    {        if(num_elements_per_rank * num_processes == (int)num_elements_per_rank * num_processes)        {            local_end_position = local_start_position + ((int)num_elements_per_rank - 1);        }        else        {            local_end_position = (local_start_position + (int)num_elements_per_rank - 1) +                (((int)num_elements_per_rank * num_processes) - ((int)num_elements_per_rank * num_processes));        }    }    else    {        local_end_position = local_start_position + ((int)num_elements_per_rank - 1);    }
    input_file = MPI::File::Open(MPI::COMM_WORLD, filename, MPI::MODE_RDONLY,                    MPI::INFO_NULL);
    output_file = MPI::File::Open(MPI::COMM_WORLD, output_filename, MPI::MODE_CREATE | MPI::MODE_WRONLY, MPI::INFO_NULL);
    // filesize = input_file.Get_size();
    for(int i = local_start_position; i < local_end_position + 1; i++)    {        if(unencoded_vector[i])        {            input_file.Read_at(i * 20, buf, 20, MPI_CHAR, input_file_status);            output_file.Write_shared(buf, 20, MPI_CHAR, output_file_status);        }    }    cout << "Error";    input_file.Close();    output_file.Close();                                               MPI::Finalize();}
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