Re: [Boost-users] [mpi] irecv / send problem

Subject: Re: [Boost-users] [mpi] irecv / send problem
From: Brian Wood (woodbrian77_at_[hidden])
Date: 2009-06-15 16:04:20

Nick Collier writes:
> Hmm, I think it should work. Thanks though. The example I posted was
> modified from:

> http://ci-tutor.ncsa.illinois.edu/content.php?cid=1137

> Namely,

> /* deadlock avoided */
> #include <stdio.h>
> #include <mpi.h>

> void main (int argc, char **argv) {

> int myrank;
> MPI_Request request;
> MPI_Status status;
> double a[100], b[100];

> MPI_Init(&argc, &argv);  /* Initialize MPI */
> MPI_Comm_rank(MPI_COMM_WORLD, &myrank); /* Get rank */
> if( myrank == 0 ) {
>   /* Post a receive, send a message, then wait */
>   MPI_Irecv( b, 100, MPI_DOUBLE, 1, 19, MPI_COMM_WORLD, &request );
>   MPI_Send( a, 100, MPI_DOUBLE, 1, 17, MPI_COMM_WORLD );
>   MPI_Wait( &request, &status );
>  }
>  else if( myrank == 1 ) {
>   /* Post a receive, send a message, then wait */
>   MPI_Irecv( b, 100, MPI_DOUBLE, 0, 17, MPI_COMM_WORLD, &request );
>   MPI_Send( a, 100, MPI_DOUBLE, 0, 19, MPI_COMM_WORLD );
>   MPI_Wait( &request, &status );
>  }

> MPI_Finalize();          /* Terminate MPI */
> }
>

I am not sure why MPI was added to Boost.  Recently there was an
effort to get Boost libs ready for the next C++ standard.  I don't think
the MPI library was considered in that as it's ties to C are so strong.
Having to specify MPI_DOUBLE above when a and b are both declared
of type double is sad.  Naming it "Message Passing Interface" when
you are restricted to messages of a single type is hardly an apt name.
If it's going to be in Boost, it may wind up being called the Most Pitiful
Interface.

-- 
Brian Wood
Ebenezer Enterprises
www.webEbenezer.net
"The New Deal and Great Society entrenched a welfare mentality in
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