By The ESMF Team
ESMF release 8.1.0 is now available for download at https://github.com/esmf-org/
During the 8.1.0 development cycle, a number of exciting new features were added to the ESMF library, ease of use was improved in several areas, and performance was optimized in critical parts of the library. Highlights of the 8.1.0 release are listed below. For a detailed list of release notes please visit the release page referenced above.
The integration of the MOAB mesh library, developed by the U.S. Department of Energy, into ESMF, has reached a milestone that supports application-level testing. All users of ESMF are encouraged to begin testing their applications with the MOAB option turned ON. Preliminary results indicate that MOAB provides improved performance and scaling, and reduced memory footprint. Applications seeking to go to very high resolution grids should benefit from this new capability. The MOAB mesh feature is still OFF by default in this release, but can easily be turned ON from the application level, any time during the run. The available regridding features supported by the MOAB based implementation are clearly listed in the detailed release notes.
Another area of the library that received significant attention is the key-value storage. The new ESMF_Info class, based on a modern C++ JSON implementation, replaces ESMF_Attribute. Most of the legacy ESMF_Attribute API is preserved for backward compatibility, but users are encouraged to migrate their code to using the ESMF_Info API. As a consequence of the new key-value implementation, the NUOPC initialization time has been reduced. This is most pronounced in applications with large Field and PET counts.
Major ease of use improvements went into the NUOPC Layer. One is the introduction of semantic specialization labels into the NUOPC API. The new approach no longer uses Initialize Phase Definition (IPD) versions or the IPDvXXpY nomenclature when registering methods in the SetServices() method. This leads to clearer, more concise NUOPC “cap” implementations. Another improvement is the seamless integration of the NUOPC profiling options into the ESMF profiling infrastructure. Simply by setting the Profiling attribute on NUOPC Driver, Model, Mediator, or Connector components, it is now possible for the user to generate a detailed NUOPC-level performance profile.
A number of new features were added in the area of resource control, handling of threaded components, and shared memory access. The NUOPC layer now supports resource control and handling of threaded components. This mechanism supports hybrid MPI+OpenMP components with different threading levels, allowing each component to fully utilize HPC resources independently. Coupling between threaded components is supported automatically via the standard NUOPC Connectors. Further, data can now be shared by reference between components that run on the same compute nodes even if running with different threading levels. Both Field-level sharing and Array-level sharing are supported through the ESMF API.
New features were also added to the ESMF regridding implementation. It now supports the “nearest destination”, and “creep nearest destination” extrapolation methods. The “creep fill” extrapolation method, introduced in 8.0.0, is now available through ESMPy.
Finally 8.1.0 includes additions to improve the overall user experience with ESMF. In the area of regridding the user has now the option to specify the ‘checkFlag’ argument to ESMF_FieldRegridStore(). This turns on more comprehensive grid/mesh error checking at the cost of performance. The option should therefore be used during application development and debugging, and not during production runs. Finally, for users faced with debugging failing ESMF applications, a new section was added to the User’s Guide entitled “Debugging of ESMF User Applications” that provides some hints on how to interpret stack traces and errors that appear in the ESMF log files.
Again, for a full list of release notes and known bugs see https://earthsystemmodeling.
And as always, please write email@example.com with any questions or issues concerning ESMF.