src/Pure/ML-Systems/thread_physical_processors.ML

support for polml-5.5.2;
support Thread.numPhysicalProcessors of polyml-5.5.2 (according to SVN 1890);
clarified max_threads: store plain value internally, reproduce result only on startup, and thus avoid potential system overhead;

(*  Title:      Pure/ML-Systems/thread_physical_processors.ML
    Author:     Makarius

Emulation of structure Thread in Poly/ML 5.5.2 (SVN 1890).
*)

structure Thread =
struct
  open Thread;

  fun numPhysicalProcessors () : int option = NONE;
end;