Allow streams to operate on reduced number of PETs
@ekluzek is already working on this.
Since Nov 17, 2025.
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Description
I think this maybe something that's really done in the host code that calls streams. But, I'm adding it here in case there are changes required in CDEPS. And because the errors show up in the stream code.
If you have more processors than mesh elements in the stream file -- ESMF dies with an error because of this. AT first I thought I just needed to get an ESMF_DistGrid for the mesh file that was no more than the elements in the file. However, after trying this I see the error below that tells us that the VM for the
Errors in the PET file look like this:
20251116 014306.030 ERROR PET127 /glade/derecho/scratch/csgteam/temp/spack/derecho/24.12/builds/spack-stage-esmf-8.8.1-oigqhlcifmbqcxchruwcjowzoxz5sa4j/spack-src/src/Infrastructure/Mesh/src/ESMCI_Mesh_FileIO.C:456 ESMCI_mesh_create_from_ESMFMesh_ Value unrecognized or out of range - Can't create a Mesh from a file in a VM when that VM contains more PETs than elements in the file.
cesm.log shows it failing in the streams initialization:
dec0745.hsn.de.hpc.ucar.edu 87: Streams initialization failing for Delta14co2_in_air stream file =
dec0745.hsn.de.hpc.ucar.edu 87: /glade/campaign/cesm/cesmdata/inputdata/lnd/clm2/isotopes/ctsmforc.Graven.atm_d
dec0745.hsn.de.hpc.ucar.edu 87: elta_C14_CMIP7_4x1_global_1700-2023_yearly_v3.0_c251013.nc
dec0745.hsn.de.hpc.ucar.edu 87: ENDRUN:
dec0745.hsn.de.hpc.ucar.edu 87: ERROR in CTSMForce2DStreamBaseType.F90 at line 197
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dec0745.hsn.de.hpc.ucar.edu 107: cesm.exe 00000000011D80E0 shr_abort_mod_mp_ 67 shr_abort_mod.F90
dec0745.hsn.de.hpc.ucar.edu 107: cesm.exe 00000000005EBAB0 abortutils_mp_end 63 abortutils.F90
dec0745.hsn.de.hpc.ucar.edu 107: cesm.exe 000000000094CC14 ctsmforce2dstream 197 CTSMForce2DStreamBaseType.F90
dec0745.hsn.de.hpc.ucar.edu 107: cesm.exe 0000000000FAAA08 atmcarbonisotopes 171 AtmCarbonIsotopeStreamType.F90
dec0745.hsn.de.hpc.ucar.edu 107: cesm.exe 00000000007E780A cisoatmtimeseries 563 CNCIsoAtmTimeSeriesReadMod.F90
dec0745.hsn.de.hpc.ucar.edu 107: cesm.exe 0000000000603196 clm_initializemod 481 clm_initializeMod.F90
dec0745.hsn.de.hpc.ucar.edu 107: cesm.exe 00000000005A691B lnd_comp_nuopc_mp 677 lnd_comp_nuopc.F90
The lnd.log shows the error as well.
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