On Mon, 10 Jan 2005, Robert Borkowski wrote:
> A wget in a loop retrieving the main page of our site will occasionally take
> just under 15 minutes to complete the retrieval. Normally it takes 0.02
> seconds.
A related note: The default timeout waiting for data from the server is 15
minutes. (read_timeout).
> When I look at the access.log for that retrieval and work back to the time
> the request was placed I often find that some client out on the internet had
> issued a request with a no-cache header resulting in TCP_CLIENT_REFRESH_MISS
> for the main page.
Which will cause all clients to join this request to your server. If this
requests takes a long time to complete then all clients will experience
this delay.
> The Age + the time to retrieve the object = the read_timeout in squid.conf. I
> changed it to 9 minutes on one server and started seeing wget fail with 8+
> instead of 14+ minutes.
Ok, so your server is not finishing the page properly to Squid.
> The object is transferred quickly, but the connection stays open until some
> timer in squid elapses (read_timeout) and only then squid closes the
> connection.
Most likely there is some bytes at the end missing.
You can try working around it by setting "server_persistent_connections
off" in squid.conf, but I would recommend identifying exacly what is going
wrong first.
A good step on the way is to save a packet trace of the failing server
request
tcpdump -s 1600 -w traffic.out -i any host ip.of.your.web.server
then analyze this with ngrep / ethereal etc to try to figure out why the
response never finishes proper.
Regards
Henrik
Received on Mon Jan 10 2005 - 19:40:38 MST
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