httpd-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Thomas Eckert <>
Subject Re: mod_proxy, oooled backend connections and the keep-alive race condition
Date Fri, 02 Aug 2013 12:35:36 GMT
Yes, the theory thing ... I wish I could have added an experimental patch
for such an input filter but I'm afraid that might take a long time for me
to finish. I'll try though I hope someone more knowledgeable will pick this

On Fri, Aug 2, 2013 at 2:28 PM, Jim Jagielski <> wrote:

> +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 <>
> 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.
> >

View raw message