Could WSGI handle Asynchronous response?

Jean-Paul Calderone exarkun at
Mon Feb 18 15:35:29 CET 2008

On Mon, 18 Feb 2008 05:27:41 -0800 (PST), est <electronixtar at> wrote:
>On Feb 18, 7:05 pm, est <electronix... at> wrote:
>> I am writing a small 'comet'-like app using flup, something like this:
>> def myapp(environ, start_response):
>>     start_response('200 OK', [('Content-Type', 'text/plain')])
>>     return ['Flup works!\n']        <-------------Could this be part
>> of response output? Could I time.sleep() for a while then write other
>> outputs?
>> if __name__ == '__main__':
>>     from flup.server.fcgi import WSGIServer
>>     WSGIServer(myapp, multiplexed=True, bindAddress=('',
>> 8888)).run()
>> So is WSGI really synchronous? How can I handle asynchronous outputs
>> with flup/WSGI ?
>figured out myself :blush: :blush:
>def demo_app(environ,start_response):
>    from StringIO import StringIO
>    stdout = StringIO()
>    print >>stdout, "Hello world!"
>    print >>stdout
>    h = environ.items(); h.sort()
>    for k,v in h:
>        print >>stdout, k,'=',`v`
>    k=start_response("200 OK", [('Content-Type','text/plain')])
>    for x in range(1, 100):
>        k(str(x))
>        time.sleep(1)
>    return [stdout.getvalue()]

You can do this, but notice that you use up a thread (or a process) for
each client by doing so.  This means you'll be limited to a fairly small
number of concurrent clients.


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