MPI send and receive error not running

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?

When passing pointer variables like your sendBuf to MPI_Send or MPI_Recv, you do not need an additional &. — Hristo Iliev
– Hristo Iliev, Commented Dec 12, 2013 at 22:31

francis · Accepted Answer · 2013-12-13 00:20:33Z

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

Collectives™ on Stack Overflow

MPI send and receive error not running

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related