Although, I have not confirmed this with any tests, It seems to me that the shutdown method would prematurely close sockets on an http server used as the backend for a WebSocket server. It seems to me that the sockets that pass through the 'connection' event and never pass through the 'request' event because they are used in the WebSocket server will always be seen as idle and will be destroyed on shutdown even if the sockets are still being used by the WebSocket server.
Although, I have not confirmed this with any tests, It seems to me that the shutdown method would prematurely close sockets on an http server used as the backend for a WebSocket server. It seems to me that the sockets that pass through the 'connection' event and never pass through the 'request' event because they are used in the WebSocket server will always be seen as idle and will be destroyed on shutdown even if the sockets are still being used by the WebSocket server.