¿Cerrar todas las conexiones de enchufe (mantener vivo) en tornado?

Eventually, I hit on a solution for the kind of graceful shutdown I needed (note that this may , solamente work with Tornado 3.2, as it depends on the request having a connection and checking for the no_keep_alive attribute. Ultimately, there's no need to close a connection unless it's actively sending data (so stray existing connections don't really matter).

1. I set up a variable on the application that notes whether the application is shutting down.
2. In initialize() I check for this and if we are shutting down, I set the Connection: close header to comply with the RFC and then also set self.request.connection.no_keep_alive = True to force the connection to close before reading any more data but after the request is finished.

Relatively simple - looks something like this:

class GracefulRequestHandler(tornado.web.RequestHandler):
    def initialize(self):
        if self.application.is_shutting_down:
            self.set_header('Connection', 'close')
            self.request.connection.no_keep_alive = True

finish() doesn't apply here because a connection in the "keep-alive" state is not associated with a RequestHandler. In general there's nothing you can (or need to) do with a keep-alive connection except close it, since the browser isn't listening for a response.

Websockets are another story - in that case you may want to close the connections yourself before shutting down (but don't have to - your clients should be robust against the connection just going away).