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

Thanks for the help,

Just some clarification to understand the logic of squid: " Squid uses as many connections to each peer as there are
 maximum parallel requests needing to go to that peer"

how is it that squid has a lot less connections to each peer than the number of connections he opens to each peers?
I mean he has 3 peers to divide the requests to. So I would have thought that the number of connections to each peer will
Be roughly the number of connections to squid divided by 3.

How is the maximum parallel requests needing to go to that peer is much higher than the number of connections to squid?



Or Gerson
IT Manager

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-----Original Message-----
From: Amos Jeffries [mailto:squid3_at_treenet.co.nz]
Sent: Monday, May 16, 2011 3:29 AM
To: squid-users_at_squid-cache.org
Subject: 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

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Received on Mon May 16 2011 - 06:34:22 MDT