Legion Release 25.12.0 (December 16, 2025)

[Elliott Slaughter]

Hi all,

I'm pleased to announce that Legion 25.12.0 is now available:

• Legion
  • Re-enable out of order commit while still ensuring that deletion operations commit in-order with respect to all the operations that came before them
  • Relax getting the future size to allow it to return the result as soon as the future size is set in advance of the future being set
  • Add a field to select_tasks_to_map input struct to describe which processor's ready queue is being processed
  • Improve Legion's internal heuristics for deciding the right granularity at which to perform physical analysis to better align with the partitions being used by applications
  • Legion's physical analysis for instances now leverages our existing KD-Tree infrastructure when lots of sub-tasks are accessing the same instance from a single partition which improves the cost of analysis asymptotically
  • Bug fixes and internal refactoring
• Tools
  • Better rendering of external processors in Legion Prof
  • Use relative numbering of processors in Legion Prof
  • Bug fixes in Legion Prof
• Regent
  • Regent now assumes that Legion has been installed to some prefix, and install.py will create its own installation at language/install if none is available
  • Support for using Legion with complex support disabled
  • Fixes for linking GPU-enabled binaries

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Elliott Slaughter

"Don't worry about what anybody else is going to do. The best way to predict the future is to invent it." - Alan Kay