title: Close all (keep-alive) socket connections in tornado?
body: <p>I'm running a set of tornado instances that handles many requests from a small set of keep-alive connections. When I take down the server for maintenance I want to gracefully close the keep-alive requests so I can take the server down.  Is there a way to tell clients "Hey this socket is closing" with Tornado?  I looked around and <code>self.finish()</code> just flushes the connection.</p>