Hello everyone,

I'm trying to implement some functions in my code using parallel writing. Each processor has an array, say q, whose length is single_no(could be zero on some processors). I want to write q down to a common file, but the elements of q would be scattered to their locations in this file. The locations of the elements are described by a map. I wrote my testing code according to an example in a MPI-2 tutorial which can be found here: www.npaci.edu/ahm2002/ahm_ppt/Parallel_IO_MPI_2.ppt. This way of writing is called "Accessing Irregularly Distributed Arrays" in this tutorial and the example is given in page 42.

I tested my code with mvapich and got the result as expected. But when I tested it with openmpi, it didn't work. I tried the version 1.2.8 and 1.4 and both didn't work. I tried two clusters. Both of them are intel chips (woodcrest and nehalem), DDR infiniband with Linux system. I got some error message like

+++++++++++++++++++++++++++++++++++++++++++++++++++
[n0883:08251] *** Process received signal ***
[n0883:08249] *** Process received signal ***
[n0883:08249] Signal: Segmentation fault (11)
[n0883:08249] Signal code: Address not mapped (1)
[n0883:08249] Failing at address: (nil)
[n0883:08251] Signal: Segmentation fault (11)
[n0883:08251] Signal code: Address not mapped (1)
[n0883:08251] Failing at address: (nil)
[n0883:08248] *** Process received signal ***
[n0883:08250] *** Process received signal ***
[n0883:08248] Signal: Segmentation fault (11)
[n0883:08248] Signal code: Address not mapped (1)
[n0883:08248] Failing at address: (nil)
[n0883:08250] Signal: Segmentation fault (11)
[n0883:08250] Signal code: Address not mapped (1)
[n0883:08250] Failing at address: (nil)
[n0883:08251] [ 0] /lib64/libpthread.so.0 [0x2b4f0a2f0d60]
+++++++++++++++++++++++++++++++++++++++++++++++++++

My testing code is here:

===========================================================================================================
program test_MPI_write_adv2

!-- Template for any mpi program

implicit none

!--Include the mpi header file
include 'mpif.h'              ! --> Required statement

!--Declare all variables and arrays.
integer :: fh, ierr, myid, numprocs, itag, etype, filetype, info
integer :: status(MPI_STATUS_SIZE)
integer :: irc, ip
integer(kind=mpi_offset_kind) :: offset, disp
integer :: i, j, k

integer :: num

character(len=64) :: filename

real(8), pointer :: q(:), temp(:)
integer, pointer :: map(:)
integer :: single_no, count

!--Initialize MPI
call MPI_INIT( ierr )         ! --> Required statement

!--Who am I? --- get my rank=myid
call MPI_COMM_RANK( MPI_COMM_WORLD, myid, ierr )

!--How many processes in the global group?
call MPI_COMM_SIZE( MPI_COMM_WORLD, numprocs, ierr )

if ( myid == 0 ) then
     single_no = 4
elseif ( myid == 1 ) then
     single_no = 2
elseif ( myid == 2 ) then
     single_no = 2
elseif ( myid == 3 ) then
     single_no = 3
else
     single_no = 0
end if

if (single_no .gt. 0) allocate(map(single_no))

if ( myid == 0 ) then
     map = (/ 0, 2, 5, 6 /)
elseif ( myid == 1 ) then
     map = (/ 1, 4 /)
elseif ( myid == 2 ) then
     map = (/ 3, 9 /)
elseif ( myid == 3 ) then
     map = (/ 7, 8, 10 /)
end if

if (single_no .gt. 0) allocate(q(single_no))

if (single_no .gt. 0) then
     do i = 1,single_no
        q(i) = dble(myid+1)*100.0d0 + dble(map(i)+1)
     end do
end if

if (single_no .gt. 0) map = map + 1

if ( myid == 0 ) then
     count = 1
else
     count = 0
end if

if (count .gt. 0) then
     allocate(temp(count))
     temp(1) = 2122010.0d0
end if

write(filename,'(a)') 'test_write.bin'

call MPI_FILE_OPEN(MPI_COMM_WORLD, filename, MPI_MODE_RDWR+MPI_MODE_CREATE, MPI_INFO_NULL, fh, ierr)

call MPI_FILE_WRITE(FH, temp, COUNT, MPI_REAL8, STATUS, IERR)

call MPI_TYPE_CREATE_INDEXED_BLOCK(single_no, 1, map, MPI_DOUBLE_PRECISION, filetype, ierr)
call MPI_TYPE_COMMIT(filetype, ierr)
disp = 0
call MPI_FILE_SET_VIEW(fh, disp, MPI_DOUBLE_PRECISION, filetype, 'native', MPI_INFO_NULL, ierr)
call MPI_FILE_WRITE_ALL(fh, q, single_no, MPI_DOUBLE_PRECISION, status, ierr)
call MPI_FILE_CLOSE(fh, ierr)

if (single_no .gt. 0) deallocate(map)

if (single_no .gt. 0) deallocate(q)

if (count .gt. 0) deallocate(temp)

!--Finilize MPI
call MPI_FINALIZE(irc)        ! ---> Required statement

stop

end program test_MPI_write_adv2
===========================================================================================================

The expected result is (should be in binary but the values are as follows) :

   2122010.00000000
   101.000000000000
   202.000000000000
   103.000000000000
   304.000000000000
   205.000000000000
   106.000000000000
   107.000000000000
   408.000000000000
   409.000000000000
   310.000000000000
   411.000000000000

Can anyone help me on this problem?

Thanks a lot,
Kan