[mpich-discuss] Persistent communications between 2 computers

[Thierry Roudier]

Thanks Darius for your reply.
Unfortunately, what you suggested doesn't work. I still have the same 
error message. But as the error only occurs on some transactions, I 
avoid the crash by using MPI_Errhandler_set(..., MPI_ERRORS_RETURN). And 
I handle the error in my program.
I also saw by setting the MPI parameter "channel" to sock in the Windows 
Registry, the behavior of persistent communications is more stable.

-Thierry

On 08/09/2011 5:25 PM, Darius Buntinas wrote:
> The error message indicates that the second process was unable to look up the address of the other process.  Rather than using "localhost" use the actual address or name of the machine.  See if this helps.
>
> -d
>
>
> On Sep 8, 2011, at 1:46 AM, Thierry Roudier wrote:
>
>> Hi all,
>>
>> I want to use persistent communications to exchange data (below is the code I use). It works well on a single computer (mpiexec -n 2 teststart). But if I want to distribute the code on 2 computers (Win7) by using the command line: mpiexec -hosts 2 localhost 192.168.1.12 teststart. Unfortunately it doesn't work, and I got the following message:
>>> Fatal error in PMPI_Waitall: Other MPI error, error stack:
>>> PMPI_Waitall(274)....................: MPI_Waitall(count=2, req_array=004208B0, status_array=00420880) failed
>>> MPIR_Waitall_impl(121)...............:
>>> MPIDI_CH3I_Progress(402).............:
>>> MPID_nem_mpich2_blocking_recv(905)...:
>>> MPID_nem_newtcp_module_poll(37)......:
>>> MPID_nem_newtcp_module_connpoll(2669):
>>> gen_cnting_fail_handler(1738)........: connect failed - The semaphore timeout period has expired.
>>> (errno 121)
>>>
>>> ****** Persistent Communications *****
>>> Trials=             1
>>> Reps/trial=      1000
>>> Message Size   Bandwidth (bytes/sec)
>>> Fatal error in PMPI_Waitall: Other MPI error, error stack:
>>> PMPI_Waitall(274)....................: MPI_Waitall(count=2, req_array=004208B0, status_array=00420880) failed
>>> MPIR_Waitall_impl(121)...............:
>>> MPIDI_CH3I_Progress(402).............:
>>> MPID_nem_mpich2_blocking_recv(905)...:
>>> MPID_nem_newtcp_module_poll(37)......:
>>> MPID_nem_newtcp_module_connpoll(2655):
>>> gen_read_fail_handler(1145)..........: read from socket failed - Le nom rÚseau spÚcifiÚ nÆest plus disponible.
>> And below is the code I use.
>>
>> Thanks a lot for your help.
>>
>> -Thierry
>>
>>> #include<mpi.h>
>>> #include<stdio.h>
>>>
>>> /* Modify these to change timing scenario */
>>> #define TRIALS          1
>>> #define STEPS           1
>>> #define MAX_MSGSIZE     1048576    /* 2^STEPS */
>>> #define REPS            1000
>>> #define MAXPOINTS       10000
>>>
>>> int    numtasks, rank, tag=999, n, i, j, k, this, msgsizes[MAXPOINTS];
>>> double  mbytes, tbytes, results[MAXPOINTS], ttime, t1, t2;
>>> char   sbuff[MAX_MSGSIZE], rbuff[MAX_MSGSIZE];
>>> MPI_Status stats[2];
>>> MPI_Request reqs[2];
>>>
>>> int main(argc,argv)
>>> int argc;
>>> char *argv[];  {
>>>
>>> MPI_Init(&argc,&argv);
>>> MPI_Comm_size(MPI_COMM_WORLD,&numtasks);
>>> MPI_Comm_rank(MPI_COMM_WORLD,&rank);
>>>
>>> /**************************** task 0 ***********************************/
>>> if (rank == 0) {
>>>
>>>   /* Initializations */
>>>   n=1;
>>>   for (i=0; i<=STEPS; i++) {
>>>     msgsizes[i] = n;
>>>     results[i] = 0.0;
>>>     n=n*2;
>>>     }
>>>   for (i=0; i<MAX_MSGSIZE; i++)
>>>     sbuff[i] = 'x';
>>>
>>>   /* Greetings */
>>>   printf("\n****** Persistent Communications *****\n");
>>>   printf("Trials=      %8d\n",TRIALS);
>>>   printf("Reps/trial=  %8d\n",REPS);
>>>   printf("Message Size   Bandwidth (bytes/sec)\n");
>>>
>>>   /* Begin timings */
>>>   for (k=0; k<TRIALS; k++) {
>>>
>>>     n=1;
>>>     for (j=0; j<=STEPS; j++) {
>>>
>>>       /* Setup persistent requests for both the send and receive */
>>>       MPI_Recv_init (&rbuff, n, MPI_CHAR, 1, tag, MPI_COMM_WORLD,&reqs[0]);
>>>       MPI_Send_init (&sbuff, n, MPI_CHAR, 1, tag, MPI_COMM_WORLD,&reqs[1]);
>>>
>>>       t1 = MPI_Wtime();
>>>       for (i=1; i<=REPS; i++){
>>>         MPI_Startall (2, reqs);
>>>         MPI_Waitall (2, reqs, stats);
>>>         }
>>>       t2 = MPI_Wtime();
>>>
>>>       /* Compute bandwidth and save best result over all TRIALS */
>>>       ttime = t2 - t1;
>>>       tbytes = sizeof(char) * n * 2.0 * (float)REPS;
>>>       mbytes = tbytes/ttime;
>>>       if (results[j]<  mbytes)
>>>          results[j] = mbytes;
>>>
>>>       /* Free persistent requests */
>>>       MPI_Request_free (&reqs[0]);
>>>       MPI_Request_free (&reqs[1]);
>>>       n=n*2;
>>>       }   /* end j loop */
>>>     }     /* end k loop */
>>>
>>>   /* Print results */
>>>   for (j=0; j<=STEPS; j++) {
>>>     printf("%9d %16d\n", msgsizes[j], (int)results[j]);
>>>     }
>>>
>>>   }       /* end of task 0 */
>>>
>>>
>>>
>>> /****************************  task 1 ************************************/
>>> if (rank == 1) {
>>>
>>>   /* Begin timing tests */
>>>   for (k=0; k<TRIALS; k++) {
>>>
>>>     n=1;
>>>     for (j=0; j<=STEPS; j++) {
>>>
>>>       /* Setup persistent requests for both the send and receive */
>>>       MPI_Recv_init (&rbuff, n, MPI_CHAR, 0, tag, MPI_COMM_WORLD,&reqs[0]);
>>>       MPI_Send_init (&sbuff, n, MPI_CHAR, 0, tag, MPI_COMM_WORLD,&reqs[1]);
>>>
>>>       for (i=1; i<=REPS; i++){
>>>         MPI_Startall (2, reqs);
>>>         MPI_Waitall (2, reqs, stats);
>>>         }
>>>
>>>       /* Free persistent requests */
>>>       MPI_Request_free (&reqs[0]);
>>>       MPI_Request_free (&reqs[1]);
>>>       n=n*2;
>>>
>>>       }   /* end j loop */
>>>     }     /* end k loop */
>>>   }       /* end task 1 */
>>>
>>>
>>> MPI_Finalize();
>>>
>>> }  /* end of main */
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