[petsc-users] MPI_FILE_OPEN in PETSc crashes

[Barry Smith]

On Sep 12, 2014, at 1:34 PM, Danyang Su <danyang.su at gmail.com> 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

> 
> 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.

  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",buf
>     
>     call 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