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Subject: Re: [OMPI users] Allgather in inter-communicator bug,
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2010-05-20 13:44:01


Filed as https://svn.open-mpi.org/trac/ompi/ticket/2415.

Thanks for the bug report!

On May 20, 2010, at 1:33 PM, Edgar Gabriel wrote:

> thanks for pointing the problem out. I checked in the code, the problem
> is the MPI layer itself. The following check prevents us from doing
> anything
>
> ----
> e.g. ompi/mpi/c/allgather.c
>
> if ((MPI_IN_PLACE != sendbuf && 0 == sendcount) ||
> (0 == recvcount)) {
> return MPI_SUCCESS;
> }
> ----
>
>
> so the problem is not in the modules/algorithms but in the API layer,
> which did not encounter for intercommunicators correctly. I'll try to
> fix it.
>
> Thanks
> edgar
>
> On 05/20/2010 10:48 AM, Battalgazi YILDIRIM wrote:
> > Hi,
> >
> > you are right, I should have provided C++ and Fortran example, so I am
> > doing now
> >
> >
> > Here is "cplusplus.cpp"
> >
> > #include <mpi.h>
> > #include <iostream>
> > using namespace std;
> > int main()
> > {
> > MPI::Init();
> > char command[] = "./a.out";
> > MPI::Info info;
> > MPI::Intercomm child = MPI::COMM_WORLD.Spawn(command, NULL, 8,info, 0);
> > int a[8]={0,0,0,0,0,0,0,0};
> > int dummy;
> > child.Allgather(&dummy, 0, MPI::INT, a, 1, MPI::INT);
> > child.Disconnect();
> > cout << "a[";
> > for ( int i = 0; i < 7; i++ )
> > cout << a[i] << ",";
> > cout << a[7] << "]" << endl;
> >
> > MPI::Finalize();
> > }
> >
> >
> > Here is again "fortran.f90"
> >
> > program main
> > use mpi
> > implicit none
> > integer :: parent, rank, val, dummy, ierr
> > call MPI_Init(ierr)
> > call MPI_Comm_get_parent(parent, ierr)
> > call MPI_Comm_rank(parent, rank, ierr)
> > val = rank + 1
> > call MPI_Allgather(val, 1, MPI_INTEGER, &
> > dummy, 0, MPI_INTEGER, &
> > parent, ierr)
> > call MPI_Comm_disconnect(parent, ierr)
> > call MPI_Finalize(ierr)
> > end program main
> >
> > here is how you build and run
> >
> > -bash-3.2$ mpif90 fortran.f90
> > -bash-3.2$ mpiCC -o parent cplusplus.cpp
> > -bash-3.2$ ./parent
> > a[0,0,0,0,0,0,0,0]
> >
> >
> >
> > If I use mpich2,
> > -bash-3.2$ mpif90 fortran.f90
> > -bash-3.2$ mpiCC -o parent cplusplus.cpp
> > -bash-3.2$ ./parent
> > a[1,2,3,4,5,6,7,8]
> >
> > I hope that you can repeat this problem to see problem with OPENMPI,
> >
> > Thanks,
> >
> >
> > On Thu, May 20, 2010 at 10:09 AM, Jeff Squyres <jsquyres_at_[hidden]
> > <mailto:jsquyres_at_[hidden]>> wrote:
> >
> > Can you send us an all-C or all-Fortran example that shows the problem?
> >
> > We don't have easy access to test through the python bindings.
> > ...ok, I admit it, it's laziness on my part. :-) But having a
> > pure Open MPI test app would also remove some possible variables and
> > possible sources of error.
> >
> >
> > On May 20, 2010, at 9:43 AM, Battalgazi YILDIRIM wrote:
> >
> > > Hi Jody,
> > >
> > > I think that it is correct, you can test this example in your
> > desktop,
> > >
> > > thanks,
> > >
> > > On Thu, May 20, 2010 at 3:18 AM, jody <jody.xha_at_[hidden]
> > <mailto:jody.xha_at_[hidden]>> wrote:
> > > Hi
> > > I am really no python expert, but it looks to me as if you were
> > > gathering arrays filled with zeroes:
> > > a = array('i', [0]) * n
> > >
> > > Shouldn't this line be
> > > a = array('i', [r])*n
> > > where r is the rank of the process?
> > >
> > > Jody
> > >
> > >
> > > On Thu, May 20, 2010 at 12:00 AM, Battalgazi YILDIRIM
> > > <yildirimga_at_[hidden] <mailto:yildirimga_at_[hidden]>> wrote:
> > > > Hi,
> > > >
> > > >
> > > > I am trying to use intercommunicator ::Allgather between two
> > child process.
> > > > I have fortran and Python code,
> > > > I am using mpi4py for python. It seems that ::Allgather is not
> > working
> > > > properly in my desktop.
> > > >
> > > > I have contacted first mpi4py developers (Lisandro Dalcin), he
> > simplified
> > > > my problem and provided two example files (python.py and
> > fortran.f90,
> > > > please see below).
> > > >
> > > > We tried with different MPI vendors, the following example
> > worked correclty(
> > > > it means the final print out should be array('i', [1, 2, 3, 4,
> > 5, 6, 7, 8])
> > > > )
> > > >
> > > > However, it is not giving correct answer in my two desktop
> > (Redhat and
> > > > ubuntu) both
> > > > using OPENMPI
> > > >
> > > > Could yo look at this problem please?
> > > >
> > > > If you want to follow our discussion before you, you can go to
> > following
> > > > link:
> > > >
> > http://groups.google.com/group/mpi4py/browse_thread/thread/c17c660ae56ff97e
> > > >
> > > > yildirim_at_memosa:~/python_intercomm$ more python.py
> > > > from mpi4py import MPI
> > > > from array import array
> > > > import os
> > > >
> > > > progr = os.path.abspath('a.out')
> > > > child = MPI.COMM_WORLD.Spawn(progr,[], 8)
> > > > n = child.remote_size
> > > > a = array('i', [0]) * n
> > > > child.Allgather([None,MPI.INT <http://MPI.INT>],[a,MPI.INT
> > <http://MPI.INT>])
> > > > child.Disconnect()
> > > > print a
> > > >
> > > > yildirim_at_memosa:~/python_intercomm$ more fortran.f90
> > > > program main
> > > > use mpi
> > > > implicit none
> > > > integer :: parent, rank, val, dummy, ierr
> > > > call MPI_Init(ierr)
> > > > call MPI_Comm_get_parent(parent, ierr)
> > > > call MPI_Comm_rank(parent, rank, ierr)
> > > > val = rank + 1
> > > > call MPI_Allgather(val, 1, MPI_INTEGER, &
> > > > dummy, 0, MPI_INTEGER, &
> > > > parent, ierr)
> > > > call MPI_Comm_disconnect(parent, ierr)
> > > > call MPI_Finalize(ierr)
> > > > end program main
> > > >
> > > > yildirim_at_memosa:~/python_intercomm$ mpif90 fortran.f90
> > > >
> > > > yildirim_at_memosa:~/python_intercomm$ python python.py
> > > > array('i', [0, 0, 0, 0, 0, 0, 0, 0])
> > > >
> > > >
> > > > --
> > > > B. Gazi YILDIRIM
> > > >
> > > > _______________________________________________
> > > > users mailing list
> > > > users_at_[hidden] <mailto:users_at_[hidden]>
> > > > http://www.open-mpi.org/mailman/listinfo.cgi/users
> > > >
> > >
> > > _______________________________________________
> > > users mailing list
> > > users_at_[hidden] <mailto:users_at_[hidden]>
> > > http://www.open-mpi.org/mailman/listinfo.cgi/users
> > >
> > >
> > >
> > > --
> > > B. Gazi YILDIRIM
> > > _______________________________________________
> > > users mailing list
> > > users_at_[hidden] <mailto:users_at_[hidden]>
> > > http://www.open-mpi.org/mailman/listinfo.cgi/users
> >
> >
> > --
> > Jeff Squyres
> > jsquyres_at_[hidden] <mailto:jsquyres_at_[hidden]>
> > For corporate legal information go to:
> > http://www.cisco.com/web/about/doing_business/legal/cri/
> >
> >
> > _______________________________________________
> > users mailing list
> > users_at_[hidden] <mailto:users_at_[hidden]>
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
> >
> >
> >
> >
> > --
> > B. Gazi YILDIRIM
> >
> >
> >
> > _______________________________________________
> > users mailing list
> > users_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
>
>
>
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-- 
Jeff Squyres
jsquyres_at_[hidden]
For corporate legal information go to:
http://www.cisco.com/web/about/doing_business/legal/cri/