HTTP/2: keepalive_timeout now armed once between requests. Previously, PINGs and other frames extended possible keepalive time, making it possible to keep an open HTTP/2 connection for a long time. Now the connection is always closed as long as keepalive_timeout expires, similarly to how it happens in HTTP/1.x. Note that as a part of this change, incomplete frames are no longer trigger a separate timeout, so http2_recv_timeout (replaced by client_header_timeout in previous patches) is essentially cancelled. The client_header_timeout is, however, used for SSL handshake and while reading HEADERS frames.