<i>[T]the thread at the head of the queue only gets the semaphore once it starts running and
actually claims it; if it's too slow, somebody else might get there first. In human
interactions, this sort of behavior is considered impolite (in some cultures, at least),
though it is far from unknown.</i>
I can't make my mind up whether comparable systems in real life (e.g. bars or food kiosks)
have greater throughput when there's an ordered queue or a mess of people waiting. I suspect
that having people wait in line allows them to think of other things and not be ready when
their turn comes -- a phenomenon with parallels to the cold caches mentioned above.