[Twisted-web] connection pool

[Drew Perttula]

Tjerk.Kusters at imtech.nl wrote:
> The mods are classes like
> 
>   class module(resource.Resource):
>     def render_GET(self, request):
>        # do something
> 
> The reactor is started as:
>   reactor.listenTCP(_port, server.Site(root))
>   reactor.run( )
> 
> Some of the GET request in the mods can take some time to complete. In the
> current situation other request to the server have to wait on this request.
> 
> Is it possible to make soms kind of a thread/connection pool so that more
> then one request can be handled at the same time?
> 

That wouldn't be very twisted :). Ideally your "# do something" code 
could quickly return a deferred which would fire when the result is 
ready. (I think it's a bit more complicated than just 'return 
my_deferred', but not much.)

If the requests are spending time waiting for database requests, for 
example, you could use a non-blocking deferred API to the database. 
Worst case, if the delay is due to something that you really need to 
multi-thread, you could use t.i.threads.deferToThread on just that 
section. Then twisted would use a thread pool for the parts that need it 
and connect the rest of your code into the deferred event style.