Comments on: IE 8 Connetion Parallelism Issues

By: Ryan Breen

Ryan Breen — Tue, 18 Mar 2008 02:48:01 +0000

mrclay: My performance testing was not done with IE. I used a third party network testing tool establishing the same number of connections as IE8. I’ve run tests with far higher concurrency with this tool, so I don’t believe client-side factors contribute to the performance differences.

By: mrclay

mrclay — Tue, 18 Mar 2008 01:30:40 +0000

I suspect that my hosting provider (Dreamhost) simply canâ€™t keep up…

I’d like to see the same test run with Firefox after setting it to allow the same # of connections. I’m not thoroughly convinced that IE’s increase in concurrency would have that much impact on servers. At this point I’d be more likely to suspect IE’s networking innards than to suggest this change will bring the incredibly mature Apache to its knees with the same # of users.

By: DigitalSkyline

DigitalSkyline — Mon, 17 Mar 2008 20:55:56 +0000

I think they should have called this IE8 Alpha-at-best.

By: tazzben

tazzben — Mon, 17 Mar 2008 20:27:17 +0000

This is slightly off topic, but have you noticed some serious css padding issues with IE 8? I’ve noticed a number of places where a site works perfectly in IE7 and all “standards” browsers (Safari, Firefox, Opera) but seems to ignore padding in IE8. I’ve also noticed it’s really slow. Is it just me? I know its a beta, but it doesn’t seem like its even close to being done.

By: pmontrasio

pmontrasio — Mon, 17 Mar 2008 19:08:47 +0000

The idea of a X-concurrent-connections HTTP was the first thing I thought about when I read the article, so I vote for it! I prefer it over sensing the connection bandwidth because I want as much control as possible on my servers.

By: Ryan Breen

Ryan Breen — Mon, 17 Mar 2008 16:52:10 +0000

Thanks, Steve. That’s a great summary of the situation. My motivation for writing this article was to offer a caveat to Ajax developers who have adopted the CNAME approach. Given the interest in articles and presentations on the topic, I suspect there are more than a few smaller sites who have adopted this optimization. I would hate for my small role in publicizing connection parallelism hacks to hurt those early adopters.

By: souders

souders — Mon, 17 Mar 2008 16:36:56 +0000

IE8′s move is great – 6 connections per hostname, dropped to 2 if dialup. The main point of Ryan’s post is that sites that follow the “CNAME trick”, creating multiple hostnames to increase parallelization, should re-evaluate this strategy. This is especially true if those sites are hosted on servers that can’t handle the load. Users visiting major sites using IE8 likely won’t suffer – those sites can handle the increase in parallel connections. And users visiting smaller sites using IE8 likely won’t suffer either – smaller sites aren’t likely to have implemented the CNAME trick. Only 2 of the top 10 U.S. sites use this technique (YouTube and MSN), so it’s not likely to be widespread on smaller sites.

By: jdsharp

jdsharp — Mon, 17 Mar 2008 15:40:51 +0000

I wonder if in this situation it would make sense to introduce support for “X-concurrent-connections” header where a host could “suggest” the ideal number of connections. One advantage would be that this could dynamically change with the load on a particular provider (or even be tailored to specific browsers/networks).

By: Ryan Breen

Ryan Breen — Mon, 17 Mar 2008 15:32:58 +0000

Thanks, Kris. I was hoping they were planning a mitigation strategy like that for dial-up users.

By: sebasgt

sebasgt — Mon, 17 Mar 2008 15:17:01 +0000

Excellent work!, and for those who said that this wasn’t a problem in the other post about this, here is the answer! ;-)

By: kriszyp

kriszyp — Mon, 17 Mar 2008 14:15:06 +0000

Good work Ryan. In regards to the excessive connections, I believe IE8 is going to attempt to detect when a slow connection was being used, and go back to the 2 connection limit in those situations.