MPI send and receive error not running - mpi

Question

I have written the following code as test
I am receiving from each processor an array and I am placing them in ad 2D array each row is for an array from a different processor
#include <iostream>
#include <mpi.h>
using namespace std;
int main(int argc, char* argv[])
{
int *sendBuff;
int **table;
int size, rank;
MPI_Status stat;
int pass = 1;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
sendBuff = new int[10];
printf("task %d passed %d\n", rank, pass); //1
pass++;
if (rank == 0)
{
table = new int*[size];
}
for (int i = 0; i < 10; i++)
{
sendBuff[i] = rank;
}
printf("task %d passed %d\n", rank, pass); //2
pass++;
if (rank != 0)
{
MPI_Send(&sendBuff, 10, MPI_INT, 0, rank, MPI_COMM_WORLD);
}
printf("task %d passed %d\n", rank, pass); //3
pass++;
if (rank == 0)
{
table[0] = sendBuff;
for (int i = 1; i < size; i++)
{
MPI_Recv(&table[i], 10, MPI_INT, i, i, MPI_COMM_WORLD, &stat);
}
}
printf("task %d passed %d\n", rank, pass); //4
pass++;
delete[] sendBuff;
if (rank == 0)
{
for (int i = 0; i < size; i++)
{
delete[] table[i];
}
delete[] table;
}
MPI_Finalize();
return 0;
}
but It is not runing
I run using
mpirun -np 4 a.out
and I get the following:
[arch:03429] *** Process received signal ***
[arch:03429] Signal: Aborted (6)
[arch:03429] Signal code: (-6)
[arch:03429] [ 0] /usr/lib/libpthread.so.0(+0xf870) [0x7fd2675bd870]
[arch:03429] [ 1] /usr/lib/libc.so.6(gsignal+0x39) [0x7fd2672383d9]
[arch:03429] [ 2] /usr/lib/libc.so.6(abort+0x148) [0x7fd2672397d8]
[arch:03429] [ 3] /usr/lib/libc.so.6(+0x72e64) [0x7fd267275e64]
[arch:03429] [ 4] /usr/lib/libc.so.6(+0x7862e) [0x7fd26727b62e]
[arch:03429] [ 5] /usr/lib/libc.so.6(+0x79307) [0x7fd26727c307]
[arch:03429] [ 6] a.out() [0x408704]
[arch:03429] [ 7] /usr/lib/libc.so.6(__libc_start_main+0xf5) [0x7fd267224bc5]
[arch:03429] [ 8] a.out() [0x408429]
[arch:03429] *** End of error message ***
--------------------------------------------------------------------------
mpirun noticed that process rank 0 with PID 3429 on node arch exited on signal 6 (Aborted).
--------------------------------------------------------------------------
Any help?

Answer 1

As Hristo Iliev pointed out, the array sendBuf should be the argument of MPI_Send. It works the same way for table[i].
Another fact : MPI_Send and MPI_Recv do not allocate memory. These functions just copy a message from one place to another. Both sendBuff and table[i] should be allocated previously. And writting table[0]=sendBuff would therefore trigger a memory leak.
Here is a code that may help you :
#include <iostream>
#include <mpi.h>
using namespace std;
int main(int argc, char* argv[])
{
int *sendBuff;
int **table;
int size, rank;
MPI_Status stat;
int pass = 1;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
sendBuff = new int[10];
printf("firts task %d passed %d\n", rank, pass); //1
pass++;
if (rank == 0)
{
table = new int*[size];
}
for (int i = 0; i < 10; i++)
{
sendBuff[i] = rank;
}
printf("second task %d passed %d\n", rank, pass); //2
pass++;
if (rank != 0)
{
MPI_Send(sendBuff, 10, MPI_INT, 0, rank, MPI_COMM_WORLD);
}
printf("thrid task %d passed %d\n", rank, pass); //3
pass++;
if (rank == 0)
{
table[0]=new int[10];
for(int i=0;i<10;i++){
table[0][i]=sendBuff[i];
}
// table[0] = sendBuff;
for (int i = 1; i < size; i++)
{
table[i]=new int[10];
MPI_Recv(table[i], 10, MPI_INT, i, i, MPI_COMM_WORLD, &stat);
}
}
printf("fourth task %d passed %d\n", rank, pass); //4
pass++;
if (rank == 0)
{
for (int i = 0; i < size; i++)
{
delete [] table[i];
table[i]=NULL;
}
delete [] table;
}
delete [] sendBuff;
MPI_Finalize();
return 0;
}
A function that may help you : MPI_Gather(...). It seems to be what you are looking for ! Watch for memory allocation if you want to use it : all the values of table should be allocated as one contiguous chunk of memory.
http://www.mcs.anl.gov/research/projects/mpi/www/www3/MPI_Gather.html
Bye,
Francis