[OMPI users] Application logging

[Alberto Giannetti]

I need to log application-level messages on disk to trace my program  
activity. For better performances, one solution is to dedicate one  
processor to the actual I/O logging, while the other working  
processors would trace their activity through non-blocking, string  
message sends:

/* LOGGER PROCESSOR MAIN LOOP */
void logger(void)
{
  MPI_Status status;
  char buf[LOGMSG_MAXSIZE];
  printf("Logger: Started\n");

  while( 1 ) {
    MPI_Recv(&buf, LOGMSG_MAXSIZE, MPI_CHAR, MPI_ANY_SOURCE,  
LOGMSG_TAG, MPI_COMM_WORLD, &status);
    buf[status.count] = '\0';
    /* ACTUAL I/O */
    printf("Processor %d ==> %s\n", status.MPI_SOURCE, buf);
  }
}


/* WORKER PROCESSOR LOGGING */
void mylog(char* msg)
{
  MPI_Request req;
  int msglen = strlen(msg);

  if( msglen > LOGMSG_MAXSIZE ) {
    /* Truncate */
    msg[LOGMSG_MAXSIZE-1] = '\0';
    msglen = LOGMSG_MAXSIZE;
  }

  /* Non-blocking send */
  MPI_Isend(msg, msglen, MPI_CHAR, LOGGER, LOGMSG_TAG,  
MPI_COMM_WORLD, &req);
}


I figured this must be a common problem in MPI applications and was  
wondering if there is any library available or related discussions.