On 22 Οκτ 2013, at 3:38 μ.μ., [email protected] wrote:
> On 07:41 am, [email protected] wrote:
>> On 21 Οκτ 2013, at 10:32 μ.μ., Glyph <[email protected]> wrote:
>>>
>>> On Oct 20, 2013, at 2:21 AM, Orestis Markou <[email protected]> wrote:
>>>> Hello,
>>>>
>>>> Short form of the question:
>>>>
>>>> Are people using Twisted to host WSGI applications AND serve static files
>>>> AND replace celery/redis/other?
>>>
>>> I'm not personally using it as a WSGI host, but otherwise, yes, a
>>> full-stack application container speaking multiple protocols.
>>
>> Any pointers on how to best use this in combination with WSGI/Django? In the
>> past I had a combination of twisted-web (for /static and /media) and wsgi
>> host (for everything else), all running under the same Service. Essentially:
>>
>> os.environ['DJANGO_SETTINGS_MODULE'] = 'myproject.settings'
>> application = django.core.handlers.wsgi.WSGIHandler()
>>
>> wsgi_resource = WSGIResource(reactor, reactor.getThreadPool(), application)
>> resource = Root(wsgi_resource)
>> # this could probably be automatically inferred from settings.py
>> resource.putChild('static', File(...))
>> resource.putChild('uploaded', File(...))
>> # other stuff
>> site = server.Site(resource)
>> reactor.listenTCP(8000, site)
>> reactor.run()
>
> This looks about like I'd expect (if my guess that `Root` is an `IResource`
> that knows how to split dispatch between the WSGI resource and its other
> children). If you have any suggestions for improving the experience please
> share them. :)
For anyone following along:
class Root(resource.Resource):
def __init__(self, wsgi_resource):
resource.Resource.__init__(self)
self.wsgi_resource = wsgi_resource
def getChild(self, path, request):
path0 = request.prepath.pop(0)
request.postpath.insert(0, path0)
return self.wsgi_resource
I don't remember now if I wrote this code or if I copied it from somewhere.
>> [snip]
>>
>> Here's a thought experiment - I'd like to keep URL routing 100% in Django
>> for anything that hits the DB. I have some code that needs to spawn an
>> external process to generate an image on-demand (with a layer of caching on
>> top). In the past I defined a Twisted.Web handler for that. Could I now
>> expose an internal API that (through Crochet?) do the spawnProcess dance and
>> come back with image data that Django could then handle internally (store in
>> a file, whatever). How would the threaded WSGI container deal with the
>> blocking request (not really blocking, but that request would stall until
>> the Deferred would be fired).
>
> It will produce roughly the same results as you'd get if you used any other
> WSGI container: one of the threads in the thread pool will be kept
> unavailable as it waits for the result. This will have the usual
> consequence: if your threadpool has a max of N threads and you receive N
> requests that need to do this, the N+1th request that needs to be handled by
> the WSGI part of your server won't be handled until one of the previous
> requests completes (completion frees up one thread which is then used to
> handle the N+1th request).
>
> The only difference might be that since you also have non-WSGI content (all
> of your static content) even when your thread pool is completely in use
> requests for static content will still be satisfied right away. However, if
> you previously had a WSGI+lighttpd/whatever then you probably already had
> this property as well.
>
> Put another way, Twisted's WSGI container is still just a WSGI container.
> Fortunately Twisted has other pieces aside from a WSGI container. :)
I wonder if this could be turned on its head - instead of having the Django
WSGI app blocking while waiting for a long running thing, field the request
beforehand, do whatever long-running thing is required and only then hand over
the to the WSGI app to proceed with the HTTP response. This obviously requires
a level request processing in Twisted - I'm not sure if it's worth the effort.
It could be done by a Twisted-savvy WSGI middleware, perhaps. I'll try to see
what I can come up with.
Orestis
> Jean-Paul
>
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