Lighttpd

mod_proxy_core.c has a problem where only the FCGI_STDOUT containing the header is sent to the user agent while the request is in progress. Any further response packets were sent only after the request had ended.

The problem occurs in the PROXY_STATE_READ_RESPONSE_BODY state. If the request has not ended HANDLER_WAIT_FOR_EVENT is returned before adding new data to the send queue:

if (!sess->proxy_con->recv->is_closed && !sess->is_request_finished) {
    return HANDLER_WAIT_FOR_EVENT;
}

My patch simply moves this block of code directly after where the data is added to the send queue.