anchor.diff:    (reset-ephemeral-thread sys.int::*snapshot-thread* #'snapshot-thread :sleeping)
     (reset-ephemeral-thread sys.int::*pager-thread* #'pager-thread :runnable)
     (reset-ephemeral-thread sys.int::*disk-io-thread* #'disk-thread :runnable)
  -  (condition-notify *world-stop-resume-cvar*))
  +  (condition-notify *world-stop-cvar*))
   
   (defun wake-thread (thread)
     "Wake a sleeping thread."
  
positive.code:     (panic "Going PA with world stopped!"))
    (ensure-interrupts-enabled)
    (with-mutex (*world-stop-lock*)
      (when *world-stop-pending*
        ;; Wait for the world to stop & resume.
        (condition-wait *world-stop-resume-cvar* *world-stop-lock*))
      ;; TODO: Have a list of pseudo atomic threads, and prevent PA threads
      ;; from being inspected.
      (incf *pseudo-atomic-thread-count*))
  
negative.code:          (funcall thunk))
      (with-mutex (*world-stop-lock*)
        (decf *pseudo-atomic-thread-count*)
        (condition-notify *world-stop-cvar*))))
  
  (defmacro with-pseudo-atomic (&body body)
    `(call-with-pseudo-atomic (dx-lambda () ,@body)))
  