My understanding so far is Jetty 8(server) is based on servlet 3.0 which supports asynchronous processing but the socket IO is still blocking. So if there is a slow client processing a large response 10s of MB of size then its possible that the server thread writing the response might be in a WAIT state till the client has fully read the response even though the server can process the response much faster than the client.
Is there a work around in Jetty 8 to get past blocking socket IO