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Hello All,
This will probably turn out to be my fault as I haven't used MPI in a
few years.
I am attempting to use an MPI implementation of a "nxtval" (see the MPI
book). I am using the client-server scenario. The MPI book specifies the
three functions required. Two are collective and one is not. Only the
two collectives are tested in the supplied code. All three of the MPI
functions are reproduced in the attached code, however. I wrote a tiny
application to create and free a counter object and it fails.
I need to know if this is a bug in the MPI book and a misunderstanding
on my part.
The complete code is attached. I was using openMPI/intel to compile and
run.
The error I get is:
[compute-0-1.local:22637] *** An error occurred in MPI_Comm_rank
[compute-0-1.local:22637] *** on communicator MPI_COMM_WORLD
[compute-0-1.local:22637] *** MPI_ERR_COMM: invalid communicator
[compute-0-1.local:22637] *** MPI_ERRORS_ARE_FATAL (goodbye)
mpirun noticed that job rank 0 with PID 22635 on node
"compute-0-1.local" exited on signal 15.
I've attempted to google my way to understanding but with little
success. If someone could point me to
a sample application that actually uses these functions, I would
appreciate it.
Sorry if this is the wrong list, it is not an MPICH question and I
wasn't sure where to turn.
Thanks,
--jeff
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/* A beginning piece of code to perform large-scale web construction. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "mpi.h"
typedef struct {
char description[1024];
double startwtime;
double endwtime;
double difftime;
} Timer;
/* prototypes */
int MPE_Counter_nxtval(MPI_Comm , int *);
int MPE_Counter_free( MPI_Comm *, MPI_Comm * );
void MPE_Counter_create( MPI_Comm , MPI_Comm *, MPI_Comm *);
/* End prototypes */
/* Globals */
int rank,numsize;
int main( argc, argv )
int argc;
char **argv;
{
int i,j;
MPI_Status status;
MPI_Request r;
MPI_Comm smaller_comm, counter_comm;
int numtimings=0;
int inttemp;
int value=-1;
int server;
//Init parallel environment
MPI_Init( &argc, &argv );
MPI_Comm_rank( MPI_COMM_WORLD, &rank );
MPI_Comm_size( MPI_COMM_WORLD, &numsize );
printf("I am %i of %i WORLD procesors\n",rank,numsize);
server = numsize -1;
MPE_Counter_create( MPI_COMM_WORLD, &smaller_comm, &counter_comm );
printf("Initial inttemp %i\n",rank);
inttemp = MPE_Counter_free( &smaller_comm, &counter_comm );
printf("final inttemp %i,%i\n",rank,inttemp);
printf("%i, WORLD barrier leaving routine\n",rank);
MPI_Barrier( MPI_COMM_WORLD );
}
//// Add new MPICH based shared counter.
//// grabbed from
http://www-unix.mcs.anl.gov/mpi/usingmpi/examples/advanced/nxtval_create_c.htm
/* tag values */
#define REQUEST 0
#define GOAWAY 1
#define VALUE 2
#define MPE_SUCCESS 0
void MPE_Counter_create( MPI_Comm oldcomm, MPI_Comm * smaller_comm, MPI_Comm *
counter_comm )
{
int counter = 0;
int message, done = 0, myid, numprocs, server, color,ranks[1];
MPI_Status status;
MPI_Group oldgroup, smaller_group;
MPI_Comm_size(oldcomm, &numprocs);
MPI_Comm_rank(oldcomm, &myid);
server = numprocs-1; /* last proc is server */
MPI_Comm_dup( oldcomm, counter_comm ); /* make one new comm */
if (myid == server) color = MPI_UNDEFINED;
else color =0;
MPI_Comm_split( oldcomm, color, myid, smaller_comm);
if (myid == server) { /* I am the server */
while (!done) {
MPI_Recv(&message, 1, MPI_INT, MPI_ANY_SOURCE, MPI_ANY_TAG,
*counter_comm, &status );
if (status.MPI_TAG == REQUEST) {
MPI_Send(&counter, 1, MPI_INT, status.MPI_SOURCE, VALUE,
*counter_comm );
counter++;
}
else if (status.MPI_TAG == GOAWAY) {
printf("SERVER Got a DONE flag\n");
done = 1;
}
else {
fprintf(stderr, "bad tag sent to MPE counter\n");
MPI_Abort(*counter_comm, 1);
}
}
MPE_Counter_free( smaller_comm, counter_comm );
}
}
/*******************************/
int MPE_Counter_free( MPI_Comm *smaller_comm, MPI_Comm * counter_comm )
{
int myid, numprocs;
MPI_Comm_rank( *counter_comm, &myid );
MPI_Comm_size( *counter_comm, &numprocs );
if (myid == 0)
MPI_Send(NULL, 0, MPI_INT, numprocs-1, GOAWAY, *counter_comm);
MPI_Comm_free( counter_comm );
if (*smaller_comm != MPI_COMM_NULL) {
MPI_Comm_free( smaller_comm );
}
return 0;
}
/************************/
int MPE_Counter_nxtval(MPI_Comm counter_comm, int * value)
{
int server,numprocs;
MPI_Status status;
MPI_Comm_size( counter_comm, &numprocs );
server = numprocs-1;
MPI_Send(NULL, 0, MPI_INT, server, REQUEST, counter_comm );
MPI_Recv(value, 1, MPI_INT, server, VALUE, counter_comm, &status );
return 0;
}
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