Re: squid 2.6-rproxy

On Sunday 16 June 2002 05:23, JDW - List wrote:

> > Probably, if given a good motivation why such a thing is needed
> > and what kind of testing you have done to make sure that there
> > was no ill effects of changing this..
>
> Well, my squid hangs connections with this at its default value
> under certain circumstances. I was advised by someone more
> squid-knowledgeable than me to change it, and that solved the
> problem.

Which isn't really a motivation why it needs to be configurable, only
a weak attempt to bandaid some other problem.

> I don't even really know what it does. It looks it's got something
> to do with managing how far ahead of the client the server will
> receive from the origin server, but it's not clear to me why the
> default value causes connections to hang.

Correct description of what it does.

> It appears to be most prevalent when a lot of clients access the
> same very large file.

Which is much more important as a hint to where the problem is than
that it helps changing the read-ahead gap. If this is the problem
then the problem is in how Squid allows multiple client to reuse the
same server request while it is being processed.

Quite likely changing the read-ahead gap just lessens the probability
that the problem will occur.

> I'm not looking to change the default, just make it configurable.
> Mostly selfish reasons: to teach myself about the config interface.
> It's very questionable whether this is of value to anyone else.

So you don't really have any motivation on why this should be
configurable then.

Well, I know at least one reason why to make the read-ahead gap larger
so I'll probably put it in anyway. If you can afford the memory
needed for the read-ahead gap buffering then it helps in offloading
the webserver in reverse proxying with lots of slow clients as the
connection between Squid and the web server then finishes more
quickly, allowing the web server resources to be used for other
clients while Squid is sending the reply to the client. This benefit
is most notable on dynamic forking webservers such as Apache with
large scriptig modules such as mod_perl, mod_php or mod_python.
Received on Sun Jun 16 2002 - 07:33:26 MDT