static AutoCloseable profileThisThreadToConsole() {
  int interval = 5000, firstInterval = 1000;
  final Thread t = currentThread();
  ret timerAsAutocloseable(doEvery_daemon(interval, firstInterval, r {
    print("\nStack trace.");
    print(lines(asList(t.getStackTrace())));
  }));
}

static <A> A profileThisThreadToConsole(IF0<A> f) {
  if (f == null) null;
  temp profileThisThreadToConsole();
  ret f!;
}