Having a look at MPM event's doc ( http://httpd.apache.org/docs/current/mod/event.html#asyncrequestworkerfactor), I found this : "[...] if all workers are busy, [mpm_event] will close connections in keep-alive state even if the keep-alive timeout has not expired . "
On Fri, Aug 2, 2013 at 2:33 PM, Plüm, Rüdiger, Vodafone Group < ruediger.pl...@vodafone.com> wrote: > The typical way to solve this today is to know the keepalive timeout of > the backend and set ttl for this worker to a value a few seconds below. > So it might not work if the backend is a busy mpm_event... > > Regards > > Rüdiger > > > -----Ursprüngliche Nachricht----- > > Von: Jim Jagielski > > Gesendet: Freitag, 2. August 2013 14:29 > > An: dev@httpd.apache.org > > Betreff: Re: mod_proxy, oooled backend connections and the keep-alive > > race condition > > > > +1 for the theory, but I'm not sure if it's feasible or not. > > > > On Aug 2, 2013, at 5:28 AM, Thomas Eckert <thomas.r.w.eck...@gmail.com> > > wrote: > > > > > So I've been seeing lots of "proxy: error reading status line from > > remote server" by mod_proxy lately. Usually this is caused by the race > > condition between checking the connection state and the backend closing > > the connection due to the keep-alive timeout. As Covener pointed out to > > me in IRC, using mod_proxy_http's env variable "proxy-initial-not- > > pooled" does offer a solution to the problem albeit at the cost of > > performance. > > > > > > The call to ap_proxy_http_process_response() in mod_proxy_http.c > > eventually boils down to ap_rgetline_core() which calls ap_get_brigade() > > on r->input_filters. This looks to me like a simple input filter might > > do the trick if it only checked for a possibility to read on the socket > > and reopens the connection upon failure type "reset by peer". I took a > > short look at core_create_proxy_req() in server/core.c to see how > > connections are set up and I wonder if it's possible to recreate/reuse > > that logic in an input filter. If so, this input filter would offer a > > nice alternative if hard coding this behavior into mod_proxy/core is > > frowned upon. Simply make the filter dependant on an env variable, just > > like proxy-initial-not-pooled. > > > > >
