python wsgi behind nginx: yield not behaving as expected

[Igor Sysoev]

On Thu, Nov 03, 2011 at 12:48:30AM -0700, Matt Starcrest wrote:
> Looks like that solved it!  Thanks Igor!

Please note, that any "..._buffering off" disables caching,
so you can set it exactly on locations which should be cached:

   location /some/page {
       ..._buffering off;
   }

> From: Igor Sysoev <igor at sysoev.ru>
> To: nginx at nginx.org
> Sent: Thursday, November 3, 2011 12:12 AM
> Subject: Re: python wsgi behind nginx:  yield not behaving as expected
> 
> On Thu, Nov 03, 2011 at 12:08:49AM -0700, Matt Starcrest wrote:
> > Hi,
> > I want to run wsgi python code on a web server behind nginx.  The server needs to respond quickly to an http request, then continue to do some (slow) work after responding.  Python's yield statement seems to fit the bill, as follows:
> > 
> > def application(environ, start_response):
> >     output = get_response_quickly(environ)
> > 
> >     start_response('200 OK', [('Content-type', 'text/plain'), ('Content-Length', str(len(output)))])
> > 
> >     yield output
> >     do_slow_work()
> > 
> > If I run this wsgi in a standalone python server (I tried wsgiref, fapws, uwsgi), the caller receives the output immediately (after get_response_quickly()), as desired.  Great.  However, if I run any of these servers behind nginx, the caller doesn't receive a response until *after* do_slow_work() -- thus defeating the purpose.
> > 
> > Is there a way to make this pattern work with nginx?  Or is there a better way in general to respond quickly but continue work, without manually creating python threads / other clumsiness?
> 
> In nginx-1.0.9 or nginx-1.1.5 you can try
>    uwsgi_buffering  off;
> or 
>    sgi_buffering  off;
> depending on protocol. In any modern enough nginx version you can use
>     proxy_buffering off;
> 
> There is no way currently to disable buffering of FastCGI servers.
> 
> 
> -- 
> Igor Sysoev
> 
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-- 
Igor Sysoev