On Tue, Nov 20, 2012 at 12:08:12AM +1300, Dylan Jay wrote: > No not all responses. Zope has an object database with blob support. It only > applies to images, document, videos etc stored in the database, which is sort > of like static files. Once it's decide to send the file, the transaction can > end and the actual sending of the file is handled off to an async thread. It > doesn't apply when a html template page is being generated since the > transaction doesn't end till the last bit of the page has been generated.
OK, that's becoming a bit tricky then. > The problem I'm trying to solve is delivery very large blobs like long videos > which could take a long time to stream and aren't amenable to cache in > something like varnish. Currently while thats happening the cpu is being > underutilised. Do you know if there is something in the request that can tell you whether the request is for a large blob or a generated page ? If so, I have a solution :-) > I'm trying out setting maxconn to 2 even when dynamic requests will be > handled synchronously. At least some of the time the request will get > processed earlier increasing the cpu utilisation. I agree and this is generally what people do when running with such low limits. > The risk is a request could > get stuck behind a slow request and since haproxy has already handed off to > the backend it can't redistribute it (or it could but then it would get done > twice). In general the risk is low because if a request gets too slow and times out, there are big changes that the second request will experience the same fate. > but if there was a setting like max-active-requests=1 then that would result > in better balancing. or perhaps if there was a way to use acls with response > headers to up the maxconn while serving a video? The maxconn cannot be adjusted that way, it would be a bit dangerous. But maybe we could have a per-server active-request count and use this to offset the maxconn vs curr_conn computations when deciding whether to dequeue or not. However I still think that playing with maxconn is a bit dangerous because I'm fairly sure that your server has a hard limit you don't want to cross. And that's the goal of the maxconn setting. Willy
