[Nek5000-users] MPI IO out of usrchk routine

[nek5000-users at lists.mcs.anl.gov]

Dear Neks,

I am facing a problem with the MPI IO out of my usr supplied routine.
In this routine I interpolate the mesh on a uniform Cartesian grid. As an
output of this routine I have an array

fieldout(1:npts)

for each MPI task. Here is my MPI IO routine which calculates the offset and then packs
the byte of the lp MPI processes together in one file ux.*** where *** is ipic.


+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

      subroutine f_output(fieldout,ipic)

      include 'SIZE'
      include 'TOTAL'



      integer npts
      parameter (npts=1024)
      real fieldout(1:npts)

      integer*8 offset, disp
!      integer iostatus(MPI_STATUS_SIZE)



      integer ipic, f_off, out_fh, itask
      integer*8 f_offset(0:np-1)

      character(80) outname


!-----Calculation of the offset-----------------------------------------
      do itask=0,np-1
        f_offset(itask)=itask*npts*8
      enddo

      f_off=f_offset(nid)

!-----Conversion of integer*4 to integer*8
      offset=int(f_off,8)

      disp=0



      WRITE(outname,'("ux.",I3.3)')ipic

!-----Open files using the MPI handles
      call MPI_FILE_OPEN(nek_comm,TRIM(outname),
     &                   MPI_MODE_CREATE+MPI_MODE_WRONLY,
     &                   MPI_INFO_NULL,out_fh,ierr)



!-----Setting the correct view on the MPI handles (displacement=0)
      call MPI_FILE_SET_VIEW(out_fh,disp,MPI_BYTE,MPI_BYTE,
     &                       'native',MPI_INFO_NULL,ierr)

!-----Write data using MPI handles
      call MPI_FILE_WRITE_AT(out_fh,offset,fieldout,npts,MPI_BYTE,
     &                       MPI_STATUS_IGNORE,ierr)

!-----Close files
      call MPI_FILE_CLOSE(out_fh,ierr)

      return
      end

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

I got the following error message:


Abort(1) on node 15669 (rank 15669 in comm 1140850688): Fatal error in MPI_Info_dup: Invalid MPI_Info, error stack:

MPI_Info_dup(125): MPI_Info_dup(info=0x0, newinfo=0x1e7cfdb440) failed

MPI_Info_dup(66).: Invalid MPI_Info

Abort(1) on node 14577 (rank 14577 in comm 1140850688): Fatal error in MPI_Info_dup: Invalid MPI_Info, error stack:

MPI_Info_dup(125): MPI_Info_dup(info=0x0, newinfo=0x1e7cfdb440) failed

MPI_Info_dup(66).: Invalid MPI_Info


…. and so on.

I suspect that the communicator is not correctly set up.
I used nek_comm and also tried MPI_COMM_WORLD. The error message is the
same in both cases (see above).

Does anyone have an idea how to solve this?

Thanks in advance and best regards, Jörg.

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