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Abort when post_process is given a different grid than the restart files #1858

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Merged
sbryngelson merged 2 commits into from
Sep 13, 2026
+19 −2
Merged

Abort when post_process is given a different grid than the restart files #1858

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731dd59
Abort when post_process is given a different grid than the restart files
sbryngelson Sep 12, 2026
6f4294c
Merge branch 'master' into fix/restart-grid-mismatch
sbryngelson Sep 12, 2026
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21 changes: 19 additions & 2 deletions src/post_process/m_data_input.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -276,6 +276,8 @@ impure subroutine s_read_parallel_data_files(t_step)
integer(kind=MPI_OFFSET_KIND) :: offset
character(LEN=path_len + 2*name_len) :: file_loc
logical :: file_exist
integer(kind=8) :: file_bytes, bytes_needed
character(len=10) :: case_m_str, file_m_str
character(len=10) :: t_step_string
integer :: i

Expand All @@ -290,9 +292,24 @@ impure subroutine s_read_parallel_data_files(t_step)
end if

file_loc = trim(case_dir) // '/restart_data' // trim(mpiiofs) // 'x_cb.dat'
inquire (FILE=trim(file_loc), EXIST=file_exist)

inquire (FILE=trim(file_loc), EXIST=file_exist, SIZE=file_bytes)

! The grid file holds one cell boundary per value, so its size says which grid wrote the restart. Without
! this check a case file whose resolution no longer matches the run reads past the end of every restart
! file and post-processes silently, exiting 0 with NaN-filled output -- which is indistinguishable from
! success until someone plots it. The strided read down_sample performs touches stride*(m_glb + 1) + 1
! boundaries of a full-resolution file, so it needs more of the file, not less; only the un-strided read
! pins the size exactly, since down-sampling three grids of different size can land on the same m_glb.
if (file_exist) then
bytes_needed = (int(stride, 8)*int(m_glb + 1, 8) + 1_8)*int(storage_size(0._wp)/8, 8)
if (file_bytes < bytes_needed .or. (.not. down_sample .and. file_bytes /= bytes_needed)) then
call s_int_to_str(m_glb, case_m_str)
call s_int_to_str(int(file_bytes/int(storage_size(0._wp)/8, 8)) - 2, file_m_str)
call s_mpi_abort('Restart grid mismatch: this case has m = ' // trim(case_m_str) // ' but ' // trim(file_loc) &
& // ' was written with m = ' // trim(file_m_str) &
& // '. Post-processing must use the same grid as the run that wrote the ' &
& // 'restart files, or it reads past the end of every file and writes NaN.')
end if
data_size = m_glb + 2
call MPI_FILE_OPEN(MPI_COMM_WORLD, file_loc, MPI_MODE_RDONLY, mpi_info_int, ifile, ierr)

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