&gt; It could be open to manipulation, with people leaving the queue and rejoining from the back in order to get served more quickly.<p>This isn&#x27;t manipulation, this is pretty much the defined behaviour.  In a queue that doesn&#x27;t close, this is one of only two ways for the person at the front to ever get served.  The other way being for that person to be the only person left in the vicinity who wants the thing being queued for.