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Thread: Pages appear to stop responding

Last post 11-20-2009 8:00 AM by mrozik. 86 replies.

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05-11-2009, 12:26 PM In reply to

ianderson
Joined on 09-23-2003, 7:53 PM
Posts 22

Re: Pages appear to stop responding

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Also, it seems like a workaround would be to change the IIS connection-timeout to be higher than the FireFox default of 5 minutes. That would ensure that the connections are not closed on the server before FireFox considers them closed. This has implications regarding server resources, so it isn't ideal... but it may resolve the issue for the time being.

05-12-2009, 4:26 AM In reply to

Rovastar
Joined on 03-13-2008, 2:00 PM
London, UK
Posts 1,777

Re: Pages appear to stop responding

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pbreitz

Aha the TCP Chimney.

I have seen some issues with that reported on the forums here. It sounds a little flaky. It seems that the network card process for this is not as good at the CPU.

So I presume everyone with the problem has TCP Chimney enabled? It is disabled by default hence why didn't initially think of it. If you had a third party or even OEM build of the server they might have enabled.

It is something that I do not think I will enable at the moment.

Firefox having it's client timeout set of 5 minutes is strange. Why is it so long?

IIS has the longest http keepalive of any web server software at 120 seconds AFAIK the Apache 2 timeout is 15 seconds.

(IMHO the http keepalive timeout is far too long in IIS and hasn't been changed for years. Microsoft's IIS team have a horrible habit of keep all their default values the same version after version of IIS. I need to run some tests on connection of busy servers to get a better indicatioon of more optimal times.)

So I don't understand the rational for Firefox to have a timeout of 5 minutes. No webserver software will keep there connection open for that long. So why does the cilent do this? What a waste of resources.

I'll post something in that firefox thread/bug reports but it does seem a strange one.

http://www.iisportal.com

05-12-2009, 4:28 AM In reply to

Rovastar
Joined on 03-13-2008, 2:00 PM
London, UK
Posts 1,777

Re: Pages appear to stop responding

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ianderson:
Also, it seems like a workaround would be to change the IIS connection-timeout to be higher than the FireFox default of 5 minutes. That would ensure that the connections are not closed on the server before FireFox considers them closed. This has implications regarding server resources, so it isn't ideal... but it may resolve the issue for the time being.

Yeah that should work. It was something I hinted at before in a previous post. It is no huge deal having increased http keep alives it will just have the slight overhead of more connections being open.

http://www.iisportal.com

05-12-2009, 4:31 AM In reply to

Rovastar
Joined on 03-13-2008, 2:00 PM
London, UK
Posts 1,777

Re: Pages appear to stop responding

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More on the headaches of the TCP chimney

http://blogs.technet.com/networking/archive/2008/11/14/the-effect-of-tcp-chimney-offload-on-viewing-network-traffic.aspx

http://www.iisportal.com

05-12-2009, 8:48 AM In reply to

pbreitz
Joined on 04-30-2009, 8:08 PM
Posts 8

Re: Pages appear to stop responding

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Well, if the TCP Chimney is disabled by default, that would explain why the suggested changes did absolutely nothing. The registry values they had me add didn't exist to begin with, so I was doubtful adding a value of false would change much.

I'll try increasing the connection timeout to 300 and see what that does.

05-12-2009, 8:59 AM In reply to

ianderson
Joined on 09-23-2003, 7:53 PM
Posts 22

Re: Pages appear to stop responding

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I did not enable TCP Chimney, and I do not have any registry settings mentioning it either. It'll be interesting to see what the support staff suggest to try next...

I made the change to 300 secs on my IIS7 boxes and I can't reproduce the issue, so it seems like that is an effective workaround for those troubled by this issue. Hopefully you have the same experience.

I also mentioned to the FireFox team that they should consider changing that default timeout as it makes no sense to have such a large default value. If FF didn't have such a large timeout this issue wouldn't even be a problem to begin with!

Thanks a ton to VorlonShadow and pbreitz for helping to diagnose this incredibly frustrating problem!

05-12-2009, 9:01 AM In reply to

pbreitz
Joined on 04-30-2009, 8:08 PM
Posts 8

Re: Pages appear to stop responding

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Actually, before I go increasing the connection timeout, I'm curious what people think would be better:

Increase the connection timeout
Disable HTTP keep-alive

In theory these should both have an effect, right? Obviously they're each going to have their own impact on server resources, but which would be better for a site of modest traffic (approx 2000 visitors & 7000 pageviews / day).

I suppose the higher the pageview/visitor ratio, the more effective a higher connection timeout would be, and vice versa. But I just have no idea what scalar values to attach to each method for purposes of comparing server load.

Any thoughts?

05-12-2009, 9:06 AM In reply to

ianderson
Joined on 09-23-2003, 7:53 PM
Posts 22

Re: Pages appear to stop responding

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From a user-impact perspective I would go with increasing the connection-timeout. If you disable keep-alives altogether then the browsers will have to make tons more connections to your website for each request (resulting in slower page load times and most likely a visible performance decrease for your users). Having a higher timeout just means you'll have a bunch of dead connections hanging around on your server waiting for their 5-minute lifespan to tick away. I would vote for trying the increased timeouts first, and then move to disabling keep-alives as a last resort if you run into some major issue.

05-12-2009, 9:10 AM In reply to

pbreitz
Joined on 04-30-2009, 8:08 PM
Posts 8

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Thanks ianderson, I've bumped up the connection timeout on a few dev sites and one production site to test things out. Hopefully I'll have the same experience as you.

05-12-2009, 9:13 AM In reply to

ianderson
Joined on 09-23-2003, 7:53 PM
Posts 22

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One thing to keep in mind... if you have a load-balancer in between your server and your clients, you'll need to ensure that the balancer has a "sticky" connection timeout of 5 minutes as well. If the load-balancer swaps between two active servers within the 5-minute timeout of FF, then you'll see the same issue.

05-12-2009, 9:14 AM In reply to

Rovastar
Joined on 03-13-2008, 2:00 PM
London, UK
Posts 1,777

Re: Pages appear to stop responding

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The workaround should work. I would make the keepalive timeout 302 seconds or something just incase you get an overlap.

In theory yes they should be the same but the behavior is strange so it is unclear what it is.

The site traffic is so modest I don't think you will notice the difference of either.

I would increase the keepalive time rather than disabling. You are unlikely to hit any tcp limits or have much more overhead from these dormant connections. I think this is better than constantly recreating new connections every second.

As for testing this for comprehensive performance results I'll have to have think about what would be best.

(Edit: too slow at typing)

http://www.iisportal.com

05-12-2009, 9:19 AM In reply to

Rovastar
Joined on 03-13-2008, 2:00 PM
London, UK
Posts 1,777

Re: Pages appear to stop responding

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ianderson:
One thing to keep in mind... if you have a load-balancer in between your server and your clients, you'll need to ensure that the balancer has a "sticky" connection timeout of 5 minutes as well. If the load-balancer swaps between two active servers within the 5-minute timeout of FF, then you'll see the same issue.

Yeah, Load balancers can add another level of complexity to the http keepalive timeouts. They will need to be sticky. To be safe you can increase this.

http://www.iisportal.com