svoid stepAllWithStats_multiThreaded(Steppable s) {
  if (s cast SplittableSteppable) {
    int cores = coresToUse();
    //print("Have SplittableSteppable, cores=" + cores);
    if (cores > 1) {
      MultiThreadStepper stepper = new(s.split(cores));
      //print("Have stepper, n=" + l(stepper.steppables));
      stepAllWithStats_multiThreaded(stepper);
      ret;
    }
  }
  stepAllWithStats(s);
}

svoid stepAllWithStats_multiThreaded(final MultiThreadStepper stepper) {
  long n = 0;
  final new Flag done;
  stepper.onDone(r {
    print(n2(stepper.steps(), "step") + " in " + stepper.elapsedTime + " ms on " + n2(stepper.cores, "core"));
    done.raise();
  });
  //print("Starting stepper");
  stepper.start();
  done.waitUntilUp();
}

Began life as a copy of #1018351