[Web-SIG] Fwd: wsgiref.simple_server slow on slow network

[Robert Brewer]

Tibor Arpas wrote:
> I'm quite new to python and I ran into a performance problem with
> wsgiref.simple_server. I'm running this little program.
> 
> from wsgiref import simple_server
> 
> def app(environ, start_response):
>    start_response('200 OK', [('content-type', 'text/html')])
>    return ['*'*50000]
> 
> httpd = simple_server.make_server('',8080,app)
> try:
>    httpd.serve_forever()
> except KeyboardInterrupt:
>    pass
> 
> 
> I get many hundreds of responses/second on my local computer, which is
> fine.
> But when I access this server through our VPN it performs very bad.
> 
> I get 0.33 requests/second as compared to 7 responses/second when
> accessing 50kB static file served by IIS.
> 
> I also tried the same little program using paste.httpserver and that
> version works fast as expected.
> 
> I cannot really understand this behavior. My only thought is that the
> wsgiref version is sending the data in many chunks, and therefore the
> latency of the VPN comes into play. But I don't really know how to
> test this.

One possible answer is that wsgiref doesn't disable the Nagle algorithm
[1].
Try changing WSGIServer.server_bind to read:

    def server_bind(self):
        """Override server_bind to store the server name."""
        import socket
        self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY,
1)
        HTTPServer.server_bind(self)
        self.setup_environ()



Robert Brewer
fumanchu at aminus.org

[1] http://en.wikipedia.org/wiki/Nagle's_algorithm