Auto merge partitioned netcdf files

diag_manager/diag_data.F90

@@ -335,6 +335,7 @@ MODULE diag_data_mod
                                    !! routine is called with the optional time_init parameter.
   LOGICAL :: use_mpp_io = .false. !< false is fms2_io (default); true is mpp_io
   LOGICAL :: use_refactored_send = .false. !< Namelist flag to use refactored send_data math funcitons.
+  LOGICAL :: auto_merge_nc = .false. !< Namelist flag to automatically merge netCDF files.
 
   ! <!-- netCDF variable -->
 

diag_manager/diag_manager.F90

@@ -208,7 +208,7 @@ MODULE diag_manager_mod
        & get_ticks_per_second
   USE mpp_mod, ONLY: mpp_get_current_pelist, mpp_pe, mpp_npes, mpp_root_pe, mpp_sum
 
-  USE mpp_mod, ONLY: input_nml_file
+  USE mpp_mod, ONLY: input_nml_file, mpp_sync
 
   USE fms_mod, ONLY: error_mesg, FATAL, WARNING, NOTE, stdout, stdlog, write_version_number,&
        & fms_error_handler, check_nml_error, lowercase
@@ -230,7 +230,7 @@ MODULE diag_manager_mod
        & use_cmor, issue_oor_warnings, oor_warnings_fatal, oor_warning, pack_size,&
        & max_out_per_in_field, flush_nc_files, region_out_use_alt_value, max_field_attributes, output_field_type,&
        & max_file_attributes, max_axis_attributes, prepend_date, DIAG_FIELD_NOT_FOUND, diag_init_time, diag_data_init,&
-       & use_mpp_io, use_refactored_send
+       & use_mpp_io, use_refactored_send, auto_merge_nc
   USE diag_data_mod, ONLY:  fileobj, fileobjU, fnum_for_domain, fileobjND
   USE diag_table_mod, ONLY: parse_diag_table
   USE diag_output_mod, ONLY: get_diag_global_att, set_diag_global_att
@@ -239,6 +239,7 @@ MODULE diag_manager_mod
   USE fms_diag_outfield_mod, ONLY: fmsDiagOutfieldIndex_type, fmsDiagOutfield_type
   USE fms_diag_fieldbuff_update_mod, ONLY: fieldbuff_update, fieldbuff_copy_missvals, &
    & fieldbuff_copy_fieldvals
+  use netcdf_io_mod, ONLY: filepath_list_type, partitioned_global_files, partitioned_section_files, append_to_filepath_list
 
 #ifdef use_netCDF
   USE netcdf, ONLY: NF90_INT, NF90_FLOAT, NF90_CHAR
@@ -250,6 +251,10 @@ MODULE diag_manager_mod
   use diag_axis_mod, only: DIAG_AXIS_UGDOMAIN
 !----------
 
+use iso_fortran_env, only: compiler_version
+use iso_c_binding, only : c_int, c_char, c_ptr, c_null_ptr, c_null_char, c_new_line
+use, intrinsic :: iso_c_binding, only: c_int, c_char
+
   IMPLICIT NONE
 
   PRIVATE
@@ -258,7 +263,8 @@ MODULE diag_manager_mod
        & need_data, DIAG_ALL, DIAG_OCEAN, DIAG_OTHER, get_date_dif, DIAG_SECONDS,&
        & DIAG_MINUTES, DIAG_HOURS, DIAG_DAYS, DIAG_MONTHS, DIAG_YEARS, get_diag_global_att,&
        & set_diag_global_att, diag_field_add_attribute, diag_field_add_cell_measures,&
-       & get_diag_field_id, diag_axis_add_attribute, CMOR_MISSING_VALUE, null_axis_id
+       & get_diag_field_id, diag_axis_add_attribute, CMOR_MISSING_VALUE, null_axis_id,&
+       & exec_mppnccombine
   PUBLIC :: CENTER, NORTH, EAST !< Used for diag_axis_init
   ! Public interfaces from diag_grid_mod
   PUBLIC :: diag_grid_init, diag_grid_end
@@ -369,6 +375,28 @@ MODULE diag_manager_mod
      MODULE PROCEDURE diag_field_add_attribute_i1d
   END INTERFACE diag_field_add_attribute
 
+! ----- interface to the C function -----
+interface 
+  function exec_mppnccombine(outfile) bind(C)
+    use, intrinsic :: iso_c_binding, only: c_int, c_char
+    implicit none
+    character(kind=c_char) :: outfile
+    integer(c_int) :: exec_mppnccombine
+  endfunction exec_mppnccombine
+  function num_partitioned_files(outfile) bind(C)
+    use, intrinsic :: iso_c_binding, only: c_int, c_char
+    implicit none
+    character(kind=c_char) :: outfile
+    integer(c_int) :: num_partitioned_files
+  endfunction num_partitioned_files
+  function smallest_pix_suffix(pattern) bind(C)
+    use, intrinsic :: iso_c_binding, only: c_int, c_char
+    implicit none
+    character(kind=c_char) :: pattern
+    integer(c_int) :: smallest_pix_suffix
+  endfunction smallest_pix_suffix
+endinterface
+
 !> @addtogroup diag_manager_mod
 !> @{
 CONTAINS
@@ -3687,12 +3715,103 @@ SUBROUTINE diag_manager_end(time)
     DO file = 1, num_files
        CALL closing_file(file, time)
     END DO
+
+    ! barrier to make sure all io PEs are done closing all files to be combined.
+    call mpp_sync()
+
+    ! combine partitioned netcdf files into single file
+    if ( auto_merge_nc ) call combine_files()
+
     if (allocated(fileobjU)) deallocate(fileobjU)
     if (allocated(fileobj)) deallocate(fileobj)
     if (allocated(fileobjND)) deallocate(fileobjND)
     if (allocated(fnum_for_domain)) deallocate(fnum_for_domain)
   END SUBROUTINE diag_manager_end
 
+  subroutine combine_files()
+    integer(c_int) :: pix          ! The IO PE index within the set of IO PEs.
+    integer(c_int) :: smallest_pix ! The smallest IO PE index of the set of IO PEs writing the current section file.
+    integer(c_int) :: ireturn      ! Return code from mppnccombine
+    integer(c_int) :: niopes       ! Number of IO PEs participating in writing of global files
+    integer :: f
+    type(filepath_list_type), pointer :: current
+    type(filepath_list_type), pointer :: files_to_combine ! list of files to combined by this PE
+    character(len=:), allocatable :: filepath
+    character(kind=c_char, len=256) :: outfile
+    integer :: stdout_unit
+
+    stdout_unit = stdout()
+    niopes = 0
+    f = 0
+
+    ! Part 1 : Global diag files
+    ! loop through global diagnostic files to combine them in a round-robin fashion
+    ! where each IO PE combines one file based on the IO PE index (pix) and the file index (f)
+    files_to_combine => null() ! initialize the list of files to be combined by this PE
+    current => partitioned_global_files
+    do while (associated(current))
+      filepath = trim(adjustl(current%path))
+      outfile = filepath(1:len(filepath)-5) // c_null_char
+
+      ! get the number of files to combine (for the first file only). The number of files is the same for all global files.
+      if (niopes == 0) niopes = num_partitioned_files(outfile)
+
+      if (niopes == -1) then
+        call error_mesg('diag_manager_mod::combine_files', 'num_partitioned_files failed', FATAL)
+      end if
+
+      ! Read the IO PE index (pix) from the file suffix (e.g., 0000, 0001, etc.)
+      read(filepath(len(filepath)-3:len(filepath)),*) pix
+
+      if (mod(f, niopes) == pix) then
+         call append_to_filepath_list(outfile, files_to_combine)
+      end if
+
+      current => current%next
+      f = f + 1
+    end do
+
+    ! Part 2 : Section diag files
+    current => partitioned_section_files
+    do while (associated(current))
+      filepath = trim(adjustl(current%path))
+      outfile = filepath(1:len(filepath)-5) // c_null_char
+
+      ! Read the IO PE index (pix) from the file suffix (e.g., 0000, 0001, etc.)
+      read(filepath(len(filepath)-3:len(filepath)),*) pix
+
+      ! get the smallest IO PE index of the set of IO PEs writing the current section file
+      smallest_pix = smallest_pix_suffix(outfile)
+
+      if (smallest_pix == -1 ) then
+        call error_mesg('diag_manager_mod::combine_files', 'smallest_pix_suffix failed', FATAL)
+      end if
+
+      !print *, "pix = ", pix, " filepath = ", trim(filepath), " smallest_pix = ", smallest_pix, pix == smallest_pix
+
+      if (pix == smallest_pix) then
+        call append_to_filepath_list(outfile, files_to_combine)
+      end if
+
+      current => current%next
+    end do
+
+    ! sync all PEs before combining files
+    call mpp_sync()
+
+    ! Part 3 : Combine all files in the list
+    if (associated(files_to_combine)) then
+       current => files_to_combine
+       do while (associated(current))
+          write(stdout_unit,*) ' Combining file ' // trim(outfile)
+          ireturn = exec_mppnccombine(current%path)
+          if (ireturn /= 0) call error_mesg('diag_manager_mod::combine_files', 'mppnccombine failed for file ' // trim(current%path), FATAL)
+          current => current%next
+       end do
+    end if
+
+  end subroutine combine_files
+
   !> @brief Replaces diag_manager_end; close just one file: files(file)
   SUBROUTINE closing_file(file, time)
     INTEGER, INTENT(in) :: file
@@ -3789,7 +3908,7 @@ SUBROUTINE diag_manager_init(diag_model_subset, time_init, err_msg)
          & max_num_axis_sets, max_files, use_cmor, issue_oor_warnings,&
          & oor_warnings_fatal, max_out_per_in_field, flush_nc_files, region_out_use_alt_value, max_field_attributes,&
          & max_file_attributes, max_axis_attributes, prepend_date, use_mpp_io, field_log_separator,&
-         & use_refactored_send
+         & use_refactored_send, auto_merge_nc
 
     ! If the module was already initialized do nothing
     IF ( module_is_initialized ) RETURN

diag_manager/diag_output.F90

@@ -42,7 +42,7 @@ MODULE diag_output_mod
        & get_domainUG, get_diag_axis_name
   USE diag_data_mod, ONLY: pack_size, diag_fieldtype, diag_global_att_type, CMOR_MISSING_VALUE, diag_atttype, files
   USE time_manager_mod, ONLY: get_calendar_type, valid_calendar_types
-  USE fms_mod, ONLY: error_mesg, mpp_pe, write_version_number, fms_error_handler, FATAL, note
+  USE fms_mod, ONLY: error_mesg, write_version_number, fms_error_handler, FATAL, note
 
 #ifdef use_netCDF
   USE netcdf, ONLY: NF90_INT, NF90_FLOAT, NF90_CHAR