Hi,
We use squid together with a content scanner connected as parent proxy
(cache_peer parent) with none of them caching any content. When
upgrading from squid 2.7 to 3.1, we observed an increased number of TCP
connections between squid and its parent. I analysed the traffic between
squid and the parent proxy (for both squid versions), and found (among
some differences in HTTP version and (Proxy-)Connection header) that the
usage of persistent connections has changed. In squid 2.7, a persistent
connection to the parent proxy is shared for multiple origin servers,
while in squid 3.1, there is at least one connection per origin server.
Obviously, this results in a much higher total number of connections.
Is there a possibility to influence this behaviour? To me, it looks like
this is related to the introduced Connection Pinning [1] feature.
As a workaround, I see the option to reduce the number of open
persistent connections through pconn_timeout, but this will have an
impact on other connections as well which could reduce performance.
Regards,
Mathias
[1] http://wiki.squid-cache.org/Features/ConnPin
