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Increase default PnetCDF header size to avoid I/O hangs #1386

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Increase default PnetCDF header size to avoid I/O hangs #1386

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4b45fa7
Increase default PnetCDF header size to 128 KB
amstokely Dec 12, 2025
c95d83a
Added call to MPI_Free_Info.
Dec 19, 2025
8ab9e9e
Reverted all unnecessary changes to ncmpi_create calls.
Dec 29, 2025
8c62019
Moved info declaration to the beginning of the #ifdef SMIOL_PNETCDF b…
Dec 29, 2025
8535b8f
Fixed inconsistent formatting.
Dec 29, 2025
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9 changes: 7 additions & 2 deletions src/external/SMIOL/smiol.c
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
#define PNETCDF_DEFINE_MODE 0
#define PNETCDF_DATA_MODE 1
#define MAX_REQS 256
#define PNETCDF_HEADER_ALIGN_SIZE_STR "131072"
#endif

#define START_COUNT_READ 0
Expand Down Expand Up @@ -324,6 +325,7 @@ int SMIOL_open_file(struct SMIOL_context *context, const char *filename,
/*
* Convert fformat to a PNetCDF file creation mode
*/
MPI_Info info = MPI_INFO_NULL;
int filecmode;
if (fformat == SMIOL_FORMAT_CDF2) {
filecmode = NC_64BIT_OFFSET;
Expand All @@ -336,11 +338,14 @@ int SMIOL_open_file(struct SMIOL_context *context, const char *filename,
MPI_Comm_free(&io_group_comm);
return SMIOL_INVALID_FORMAT;
}

MPI_Info_create(&info);
MPI_Info_set(info, "nc_header_align_size",
PNETCDF_HEADER_ALIGN_SIZE_STR);
ierr = ncmpi_create(io_file_comm, filename,
(filecmode | NC_CLOBBER),
MPI_INFO_NULL,
info,
&((*file)->ncidp));
MPI_Info_free(&info);
}
(*file)->state = PNETCDF_DEFINE_MODE;
#endif
Expand Down