Re: [petsc-users] MPI_FILE_OPEN in PETSc crashes

Danyang Su Fri, 12 Sep 2014 14:08:50 -0700

On 12/09/2014 12:10 PM, Barry Smith wrote:

On Sep 12, 2014, at 1:34 PM, Danyang Su <[email protected]> wrote:

Hi There,

I have some parallel mpi output codes that works fine without PETSc but crashes when 
compiled with PETSc. To make the problem easy, I test the following example which has the 
same problem. This example is modified form 
http://www.mcs.anl.gov/research/projects/mpi/usingmpi2/examples/starting/io3f_f90.htm. It 
works without PETSc but if I comment out "use mpi" and add PETSc include, it 
crashes at MPI_FILE_OPEN because of access violation.

   You should not comment out use mpi; you need that to use the MPI calls you 
are making!

   You absolutely should have an implicit none at the beginning of your program 
so the Fortran compiler reports undeclared variables

Done

Shall I rewrite all the MPI Parallel output with PetscBinaryOpen or 
PetscViewerBinaryOpen relative functions?

    No.  You should be able to use the MPI IO with PETSc code.

    First figure out how to get the example working with the use mpi  PLUS 
petsc include files.

The problem is there is a lot of name conflict if both "use mpi" and"petsc include" are included. I will consider rewrite these routines.


   Let us know if you have any problems ASAP

    Barry

Considering the parallel I/O efficiency, which is more preferable?

Thanks and regards,

Danyang

PROGRAM main
     ! Fortran 90 users can (and should) use
     !use mpi
     ! instead of include 'mpif.h' if their MPI implementation provides a
     ! mpi module.
     !include 'mpif.h'

!For PETSc, use the following "include"s

#include <finclude/petscsys.h>
#include <finclude/petscviewer.h>
#include <finclude/petscviewer.h90>
     integer ierr, i, myrank, BUFSIZE, thefile
     parameter (BUFSIZE=10)
     integer buf(BUFSIZE)
     integer(kind=MPI_OFFSET_KIND) disp

call MPI_INIT(ierr)

     call MPI_COMM_RANK(MPI_COMM_WORLD, myrank, ierr)

do i = 1, BUFSIZE

         buf(i) = myrank * BUFSIZE + i
     enddo

write(*,'(a,1x,i6,1x,a,1x,10(i6,1x))') "myrank", myrank, "buf",bufcall MPI_FILE_OPEN(MPI_COMM_WORLD, 'testfile.txt', &

                        MPI_MODE_CREATE + MPI_MODE_WRONLY, &
                        MPI_INFO_NULL, thefile, ierr)
     ! assume 4-byte integers
     disp = myrank * BUFSIZE * 4

!Use the following two functions

     !call MPI_FILE_SET_VIEW(thefile, disp, MPI_INTEGER, &
     !                       MPI_INTEGER, 'native', &
     !                       MPI_INFO_NULL, ierr)
     !call MPI_FILE_WRITE(thefile, buf, BUFSIZE, MPI_INTEGER, &
     !                    MPI_STATUS_IGNORE, ierr)

!Or use the following one function

     call MPI_FILE_WRITE_AT(thefile, disp, buf, BUFSIZE, MPI_INTEGER, &
                         MPI_STATUS_IGNORE, ierr)

call MPI_FILE_CLOSE(thefile, ierr)

     call MPI_FINALIZE(ierr)

END PROGRAM main

Re: [petsc-users] MPI_FILE_OPEN in PETSc crashes

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