Re: IIS times out on large post requests

From: Willy Tarreau <>
Date: Thu, 10 Jul 2008 19:57:09 +0200

Hi Rainer,

On Thu, Jul 10, 2008 at 11:32:30AM +0200, Rainer Sabelka wrote:
> My kernel is 2.6.24-19 (ubuntu 8.04 server edition).
> I have already disabled sack but that did not help (also disabling
> tcp_window_scaling didn't have an effect).
> I also disabled tcp_frto (to solve a problem with one user who always got
> timeouts when dowloading large documents)

OK. Tried this too :-)

> I've applied the patch but deployed it only on my test-system, but there I
> cannot reproduce the problem.
> But I'll install the patched version on the production system in the evening -
> and we will see tomorrow if it solves the problem.


> PS: I'm not even sure if this problem is caused by haproxy at all - there are
> so many components in the chain, any of them could theoretically be the
> culprit:
> internet explorer 6 -> iptables firewall -> apache 2.2.8 (with mod_ssl and
> mod_proxy) -> haproxy -> IIS 6
> But haproxy is for me the most logical place to start debugging.

OK. However, haproxy says the server does not respond, while the server says the request is too short. One more reason to start looking at haproxy :-)

> Is there a
> possibility to log the actual size of the request body, so that I can compare
> it with the content length?

Unfortunately not, but it should not be too much complicated to add it (just that it would change the log format). If you're willing to try it, simply modify the logging function (http_sess_log I believe, from memory) to include the session's byte counters. You already have the byte counter for the response, simply add the request next to it. Keep in mind that it accounts for the whole request, headers included. But that will definitely help in your case.

Willy Received on 2008/07/10 19:57

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