Re: [OMPI users] Problem to Run Hello World on a desktop with Cygwin and OpenMPI 1.7.5

[Marco Atzeri]

On 30/05/2014 13:45, Sergii Veremieiev wrote:

Dear Sir/Madam,

I'm trying to compile and run a simple "Hello World" C++/MPI code on my
personal desktop machine (6-core Intel Core i7-3930K CPU with Windows 7
SP1 and Cygwin with the default built-in Open MPI 1.7.5 and GCC 4.8.2).
I'm beginner with this, never run parallel codes on desktops, only on a
cluster. Here is the code:

using namespace std;

#include "mpi.h"

int main(int argc, char *argv[])

{

    int noprocs, nid;

    MPI::Init(argc,argv);

    nid = MPI::COMM_WORLD.Get_rank();

    noprocs = MPI::COMM_WORLD.Get_size();

    if (nid==0) cout << "Hello from processor " << nid << " of " <<
noprocs << endl;

    MPI::Finalize();

}

Using “mpicxx -o Hello Hello.cpp” the code compiles without any problems
and generates an executable. However when I try to run the code using
“mpirun -np 1 Hello” or “mpiexec -n 1 Hello” the following error message
is returned:

Hi Sergii

mpirun -np 1 ./Hello
 works fine for me : "Hello from processor 0 of 1"

As the message is
"opal_os_dirpath_create: Error: Unable to create the sub-directory
/tmp/openmpi-sessions-enrsvere@byenr502b-01f_0/11302"

you need to check the location and permission of /tmp

You can also follows guidelines on https://cygwin.com/problems.html
and follow up on cygwin mailing list https://cygwin.com/lists.html


Not relevant, but please note your code is missing something as

$ mpirun -np 4 ./Hello
Hello from processor 0 of 4


While the standard hello_cxx.cc
----------------------------
#include "mpi.h"
#include <iostream>

int main(int argc, char **argv)
{
    int rank, size, len;
    char version[MPI_MAX_LIBRARY_VERSION_STRING];

    MPI::Init();
    rank = MPI::COMM_WORLD.Get_rank();
    size = MPI::COMM_WORLD.Get_size();
    MPI_Get_library_version(version, &len);
    std::cout << "Hello, world!  I am " << rank << " of " << size
              << "(" << version << ", " << len << ")" << std::endl;
    MPI::Finalize();

    return 0;
}
-------------------------------

produces

 $ mpirun -np 4 ./hello_cxx
Hello, world!  I am 1 of 4 ...
Hello, world!  I am 0 of 4 ...
Hello, world!  I am 2 of 4 ...
Hello, world!  I am 3 of 4 ...