Ouch! I was using the Bcast and thinking of it as a Send... :)
Thank you very much!
George Bosilca escreveu:
Any collective communication has to be performed by all processes in
the communicator. You example should be Bcast on all nodes.
george.
On Mar 13, 2008, at 5:50 PM, Giovani wrote:
Hello OpenMPI people!
I think that my openmpi install is somewhat strange. I'm simply
incapable of performing the simplest Recv operations.
I've installed openmpi using the default gentoo linux package. It
compiled without any problems. The version is sys-cluster/openmpi-1.2.5.
Now let's use the following program as a test:
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#include <iostream>
#include "mpicxx.h"
using namespace std;
int main(int argc, char *argv[])
{
MPI::Init();
//If we are process 0:
if ( MPI::COMM_WORLD.Get_rank() == 0 )
{
double d = 5;
cout << "Starting to send data from node 0..." << endl;
MPI::COMM_WORLD.Bcast( &d, 1, MPI::DOUBLE, 0);
cout << "Finished to send data from node 0..." << endl;
}
//Else:
else
{
MPI::Status mpi_status;
double d = 0;
cout << "Starting to receive data from node 0..." << endl;
MPI::COMM_WORLD.Recv(&d, 1, MPI::DOUBLE, MPI::ANY_SOURCE,
MPI::ANY_TAG, mpi_status );
cout << "Finished to receive data from node 0..." << endl;
};
MPI::COMM_WORLD.Barrier();
MPI::Finalize();
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
I'm calling it with this command:
/usr/bin/mpirun --hostfile mpi-config.txt -np 3
/home/gfaccin/desenvolvimento/Eclipse/mpiplay/Debug/mpiplay
Where the hostfile mpi-config.txt contains the following line:
localhost slots=1
The slots thing is just to tell openmpi that I'm running it on a single
processor PC with oversubscribed nodes. Running the program without
using host files leads to the same results.
Once the program starts, I get this output:
Starting to send data from node 0...
Finished to send data from node 0...
Starting to receive data from node 0...
Starting to receive data from node 0...
And that's it. Processor usage goes to 100% and stays like that forever.
The output indicates that the Recv functions have hung.
I've tried to reinstall the package in case something is broken, but
nothing changed.
Would you have any clues on how can I fix this?
Thank you very much!
Giovani
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