> > Once again, what's wrong with your initial approach of ceiling the
timeout?
>
> It looks like changing the rounding method doesn't solve anything.
> selector.select(timeout) may still take less than timeout, so it
> doesn't give any guarantee.

But what problem does it cause if, once in a while, the call takes less
than the passed timeout?
If that's the case, you'll simply perform another loop, an wake up 1ms
later, that's all.

There's a lot of call written this way, and this has never been a problem:
so far, you still didn't give an example of problematic behavior.