parallel-io/fortran/spokesman.f90

+program pario
+  use mpi
+  use, intrinsic :: iso_fortran_env, only : error_unit, output_unit
+  implicit none
+
+  integer, parameter :: datasize = 64, writer_id = 0
+  integer :: rc, my_id, ntasks, localsize, i
+  integer, dimension(:), allocatable :: localvector
+  integer, dimension(datasize) :: fullvector
+
+  call mpi_init(rc)
+  call mpi_comm_size(mpi_comm_world, ntasks, rc)
+  call mpi_comm_rank(mpi_comm_world, my_id, rc)
+
+  if (ntasks > 64) then
+     write(error_unit, *) 'Maximum number of tasks is 64!'
+     call mpi_abort(MPI_COMM_WORLD, -1, rc)
+  end if
+
+  if (mod(datasize, ntasks) /= 0) then
+     write(error_unit,*) 'Datasize (64) should be divisible by number of tasks'
+     call mpi_abort(MPI_COMM_WORLD, -1, rc)
+  end if
+
+  localsize = datasize / ntasks
+  allocate(localvector(localsize))
+
+  localvector = [(i + my_id * localsize, i=1,localsize)]
+
+  call single_writer()
+
+  deallocate(localvector)
+  call mpi_finalize(rc)
+
+contains
+
+  subroutine single_writer()
+    implicit none
+
+    ! TODO: Implement a function that writers the whole array of elements
+    !       to a file so that single process is responsible for the file io
+
+  end subroutine single_writer
+
+end program pario

parallel-io/fortran/spokesman_reader.f90

+program pario
+  use mpi
+  use, intrinsic :: iso_fortran_env, only : error_unit, output_unit
+  implicit none
+
+  integer, parameter :: datasize = 64, writer_id = 0
+  integer :: rc, my_id, ntasks, localsize, i
+  integer, dimension(:), allocatable :: localvector
+  integer, dimension(datasize) :: fullvector
+
+  call mpi_init(rc)
+  call mpi_comm_size(mpi_comm_world, ntasks, rc)
+  call mpi_comm_rank(mpi_comm_world, my_id, rc)
+
+  if (ntasks > 64) then
+     write(error_unit, *) 'Maximum number of tasks is 64!'
+     call mpi_abort(MPI_COMM_WORLD, -1, rc)
+  end if
+
+  if (mod(datasize, ntasks) /= 0) then
+     write(error_unit, *) 'Datasize (64) should be divisible by number of tasks'
+     call mpi_abort(MPI_COMM_WORLD, -1, rc)
+  end if
+
+  localsize = datasize / ntasks
+  allocate(localvector(localsize))
+
+  localvector = [(i + my_id * localsize, i=1,localsize)]
+
+  call single_reader()
+
+  call ordered_print()
+
+  deallocate(localvector)
+  call mpi_finalize(rc)
+
+contains
+
+  subroutine single_reader()
+    implicit none
+
+    ! TODO: Implement a function that will read the data from a file so that
+    !       a single process does the file io. Use rank WRITER_ID as the io rank
+
+  end subroutine single_reader
+
+  subroutine ordered_print
+    implicit none
+    integer :: task
+
+    do task = 0, ntasks-1
+       if (my_id == task) then
+          write(output_unit, '(A,I0,A)', advance='no') 'Task ', &
+               & my_id, ' received:'
+          do i = 1, localsize
+             write(output_unit, '(I3)', advance='no') localvector(i)
+          end do
+          write(output_unit,*) ' '
+       end if
+       call mpi_barrier(MPI_COMM_WORLD, rc)
+    end do
+
+  end subroutine ordered_print
+
+
+end program pario