Re: [squid-users] squid too many connections to cache_peers

 On Sun, 15 May 2011 15:05:52 +0000, Or Gerson wrote:
> Hello everyone,
>
> I have squid 3.0.STABLE19-1 installed.
> And 3 apache cache_peers.
>
> I find that squid is opening a lot of connections to the web servers
> a lot more than the connections he is receiving from clients, also
> squid doesn't close them and they are in TIME_WAIT status.
> For example: in squid I see 324 TIME_WAIT connections
> On each server I see around 800 TIME_WAIT connections

 TIME_WAIT is a closing connection.
 ESTABLISHED is an open connection.

 This explains:
 http://www.developerweb.net/forum/showthread.php?t=2941

>
> The cache_peers are configured with round-robin, but why squid
> doesn't closes the connections?
>
> Can't squid use one connection for each peer and send and receive all
> requests through that connection (although that probably will cause
> performance problems in the apache side because he won't uses all
> apache server processes)?

 One connection to each is indeed a performance bottleneck. Pipelining
 is also not safe for HTTP/1.0 software (ie Squid 3.0 and older) without
 great risk of breakage (just ask Debian people about apt-get corruption
 problems). Squid uses as many connections to each peer as there are
 maximum parallel requests needing to go to that peer. Enable
 server_persistent_connections to servers and Squid will re-use
 connections as much as possible given the HTTP support version.

 An upgrade to 3.1 series Squid will get you HTTP/1.1 connections to
 servers and peers. This gives a lot better re-use of the connections
 than HTTP/1.0 connection support in 3.0 series can. Provided Apache
 plays along and uses HTTP/1.1 features to prevent early TCP link
 closure.

 Amos
Received on Mon May 16 2011 - 00:29:26 MDT