Hello! On Sat, Mar 09, 2013 at 10:43:47PM +0800, Ji Zhang wrote:
> Hi, > > I'm doing some research on FastCGI recently. As I see from the FastCGI > specification, it does support multiplexing through a single > connection. But apparently none of the current web servers, like > Nginx, Apache, or Lighttpd supports this feature. > > I found a thread from nginx dev mailing list back to 2009, stating > that multiplexing won't make much difference in performance: > http://forum.nginx.org/read.php?29,30275,30312 > > But I also find an interesting article on how great this feature is, > back to 2002: > http://www.nongnu.org/fastcgi/#multiplexing This article seems to confuse FastCGI multiplexing with event-based programming. Handling multiple requests in a single process is great - and nginx does so. But you don't need FastCGI multiplexing to do it. > I don't have the ability to perform a test on this, but another > protocol, SPDY, that recently becomes very popular, and its Nginx > patch is already usable, also features multiplexing. So I'm curious > about why spdy's multiplexing is great while fastcgi's is not. > > One reason I can think of is that tcp connection on the internet is > expensive, affecting by RTT, CWND, and other tube warming-up issue. > But tcp conneciton within IDC (or unix-domain socket on localhost) is > much cheaper. Besides, the application can also go the event-based > way, to accept as much connections as it can from the listening socket > and perform asynchronously. > > Does my point make sense? or some other more substantial reasons? You are correct, since FastCGI is used mostly for local communication, multiplexing on application level isn't expected to be beneficial. Another reason is that multiplexing isn't supported (and probably will never be) by the major FastCGI application - PHP. There were several discussions on FastCGI multiplexing here, and general consensus seems to be that FastCGI multiplexing might be useful to reduce costs of multiple long-polling connections to an application, as it will reduce number of sockets OS will have to maintain. It's yet to be demonstrated though. -- Maxim Dounin http://nginx.org/en/donation.html _______________________________________________ nginx mailing list [email protected] http://mailman.nginx.org/mailman/listinfo/nginx
