Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

Subject: Re: [OMPI users] Problem with mpi_comm_spawn_multiple
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2010-05-07 17:02:48


Greetings Fred.

After looking at this for more hours than I'd care to admit, I'm wondering if this is a bug in gfortran. I can replicate your problem with a simple program on gfortran 4.1 on RHEL 5.4, but it doesn't happen with the Intel Fortran compiler (11.1) or the PGI fortran compiler (10.0).

One of the issues appears how to determine how Fortran 2d CHARACTER arrays are terminated. I can't figure out how gfortran is terminating them -- but intel and PGI both terminate them by having an empty string at the end.

Are you using gfortran 4.1, perchance?

On May 5, 2010, at 2:08 PM, Fred Marquis wrote:

> Hi,
>
> I am using mpi_comm_spawn_multiple to spawn multiple commands with argument lists. I am trying to do this in fortran (77) using version openmpi-1.4.1 and the ifort compiler v9.0. The operating system is SuSE Linux 10.1 (x86-64).
>
> I have put together a simple controlling example program (test_pbload.F) and an example slave program (spray.F) to try and explain my problem.
>
> In the controlling program mpi_comm_spawn_multiple is used to set 2 copies of the slave running. The first is started with the argument list "1 2 3 4" and the second with "5 6 7 8".
>
> The slaves are started OK and the slaves print out the argument lists and exit. In addition the slaves print out their rank numbers so I can see which argument list belongs to which slave.
>
> What I am finding is that the argument lists are not being sent to the slaves correctly, indeed both slaves seem to be getting both arguments lists !!!
>
> To compile and run the programs I follow the steps below.
>
> Controlling program "test_pbload.F"
>
> mpif77 -o test_pbload test_pbload.F
>
> Slave program "spray.F"
>
> mpif77 -o spray spray.F
>
> Run the controller
>
> mpirun -np 1 test_pbload
>
>
>
>
> The output of which is from the first slave:
>
> nsize, mytid: iargs 2 0 : 2
> spray: 0 1:1 2 3 4 < FIRST ARGUMENT
> spray: 0 2:4 5 6 7 < SECOND ARGUMENT
>
> and the second slave:
>
> nsize, mytid: iargs 2 1 : 2
> spray: 1 1:1 2 3 4 < FIRST ARGUMENT
> spray: 1 2:4 5 6 7 < SECOND ARGUMENT
>
> In each case the arguments (2 in both cases) are the same.
>
> I have written a C version of the controlling program and everthing works as expected so I presume that I have either got the specification of the argument list wrong or I have discovered an error/bug. At the moment I working on the former -- but am at a loss to see what is wrong !!
>
> Any help, pointers etc really appreciated.
>
>
> Controlling program (that uses MPI_COMM_SPAWN_MULTIPLE) test_pbload.F
>
> program main
> c
> implicit none
> #include "mpif.h"
>
> integer error
> integer intercomm
> CHARACTER*25 commands(2), argvs(2, 2)
> integer nprocs(2),info(2),ncpus
> c
> call mpi_init(error)
> c
> ncpus = 2
> c
> commands(1) = ' ./spray '
> nprocs(1) = 1
> info(1) = MPI_INFO_NULL
> argvs(1, 1) = ' 1 2 3 4 '
> argvs(1, 2) = ' '
> c
> commands(2) = ' ./spray '
> nprocs(2) = 1
> info(2) = MPI_INFO_NULL
> argvs(2, 1) = ' 4 5 6 7 '
> argvs(2, 2) = ' '
> c
> call mpi_comm_spawn_multiple( ncpus,
> 1 commands, argvs, nprocs, info,
> 2 0, MPI_COMM_WORLD, intercomm,
> 3 MPI_ERRCODES_IGNORE, error )
> c
> call mpi_finalize(error)
> c
> end
>
> Slave program (started by the controlling program) spray.F
>
> program main
> integer error
> integer pid
> character*20 line(100)
> call mpi_init(error)
> c
> CALL MPI_COMM_SIZE(MPI_COMM_WORLD,NSIZE,error)
> CALL MPI_COMM_RANK(MPI_COMM_WORLD,MYTID,error)
> c
> iargs=iargc()
> write(*,*) 'nsize, mytid: iargs', nsize, mytid, ":", iargs
> c
> if( iargs.gt.0 ) then
> do i = 1, iargs
> call getarg(i,line(i))
> write(*,'(1x,a,i3,20(i2,1h:,a))')
> 1 'spray: ',mytid,i,line(i)
> enddo
> endif
> c
> call mpi_finalize(error)
> c
> end
>
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users
>

-- 
Jeff Squyres
jsquyres_at_[hidden]
For corporate legal information go to:
http://www.cisco.com/web/about/doing_business/legal/cri/