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Subject: [OMPI users] Client/Server test
From: Alberto Giannetti (albertogiannetti_at_[hidden])
Date: 2008-04-26 00:31:54

I want to connect two MPI programs through the MPI_Comm_connect/
MPI_Comm_Accept API.
This is my server app:

int main(int argc, char* argv[])
   int rank, count;
   int i;
   float data[100];
   char myport[MPI_MAX_PORT_NAME];
   MPI_Status status;
   MPI_Comm intercomm;

   MPI_Init(&argc, &argv);
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
   printf("Processor %d (%d, Receiver) initialized\n", rank, getpid());

   MPI_Open_port(MPI_INFO_NULL, myport);
   printf("Opened port %s\n", myport);

   printf("Waiting for connections on %s...\n", myport);
   MPI_Comm_accept(myport, MPI_INFO_NULL, 0, MPI_COMM_SELF, &intercomm);
   printf("New connection on port %s\n", myport);

   printf("Processor %d waiting for data from new intercomm...\n",
intercomm, &status);
   MPI_Get_count(&status, MPI_FLOAT, &count);
   printf("Processor %d got %d elements: %f, %f, %f...\n", rank,
count, data[0], data[1], data[2]);


And my client program:

int main(int argc, char* argv[])
   int rank, i;
   float data[100];
   char myport[MPI_MAX_PORT_NAME];
   MPI_Comm intercomm;

   MPI_Init(&argc, &argv);
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
   printf("Processor %d (%d, Sender) initialized\n", rank, getpid());

   if( argc < 2 ) {
     fprintf(stderr, "Require server port name\n");

   for( i = 0; i < 100; i++ )
     data[i] = i;

   strcpy(myport, argv[1]);
   printf("Processor %d connecting to '%s'\n", rank, myport);
   MPI_Comm_connect(myport, MPI_INFO_NULL, 0, MPI_COMM_SELF,

   printf("Processor %d sending data through intercomm...\n", rank);
   MPI_Send(data, 100, MPI_FLOAT, 0, 55, intercomm);
   printf("Processor %d data sent!\n", rank);


I run the server program:

mpirun -np 2 app2
Processor 0 (7916, Receiver) initialized
Processor 1 (7918, Receiver) initialized
Opened port 0.1.0:2000
Waiting for connections on 0.1.0:2000...
Opened port 0.1.1:2001
Waiting for connections on 0.1.1:2001...

Then the client:

mpirun -np 1 app1 0.1.0:2000
Processor 0 (7933, Sender) initialized
Processor 0 connecting to '0.1.0:2000'
[alberto-giannettis-computer.local:07933] [0,1,0] ORTE_ERROR_LOG: Not
found in file /tmp/buildpackage-3432/openmpi-1.2.4/orte/dss/
dss_unpack.c at line 209
[alberto-giannettis-computer.local:07933] [0,1,0] ORTE_ERROR_LOG: Not
found in file /tmp/buildpackage-3432/openmpi-1.2.4/ompi/communicator/
comm_dyn.c at line 186
[alberto-giannettis-computer.local:07933] *** An error occurred in
[alberto-giannettis-computer.local:07933] *** on communicator
[alberto-giannettis-computer.local:07933] *** MPI_ERR_INTERN:
internal error
[alberto-giannettis-computer.local:07933] *** MPI_ERRORS_ARE_FATAL

Why do I have an internal error? If I try to connect to 0.1.1:2001
from the client the program hangs.