Re: [squid-users] squid-3.1 client POST buffering

From: Graham Keeling <>
Date: Fri, 26 Nov 2010 16:10:22 +0000

On Thu, Nov 25, 2010 at 04:36:49PM +0000, Graham Keeling wrote:
> Hello,
> I have upgraded to squid-3.1 recently, and found a change of behaviour.
> I have been using dansguardian in front of squid.
> It appears to be because squid now buffers uploaded POST data slightly
> differently.
> In versions < 3.1, it would take some data, send it through to the website,
> and then ask for some more.
> In 3.1 version, it appears to take as much from the client as it can without
> waiting for what it has already got to be uploaded to the website.
> This means that dansguardian quickly uploads all the data into squid, and
> then waits for a reply, which is a long time in coming because squid still
> has to upload everything to the website.
> And then dansguardian times out on squid after two minutes.
> I noticed the following squid configuration option. Perhaps what I need is
> a similar thing for buffering data sent from the client.
> # TAG: read_ahead_gap buffer-size
> # The amount of data the cache will buffer ahead of what has been
> # sent to the client when retrieving an object from another server.
> #Default:
> # read_ahead_gap 16 KB
> Comments welcome!
> Graham.

Upon further experimentation, I have found that squid-3.1.x (specifically,
I have tried squid-3.1.8 and squid-3.1.9) behaves very badly with POST uploads.

It just increases the input buffer forever, until the upload is finished, or
the machine runs out of memory.

This problem exists when connecting directly to squid without dansguardian
in the way.

This problem doesn't exist on my old squid-2.5 installation.
Received on Fri Nov 26 2010 - 15:58:42 MST

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