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Inline JavaScript Experiment
08-11-2010, 04:59 AM
Post: #28
RE: Inline JavaScript Experiment
(08-05-2010 05:10 AM)jklein Wrote:  Yes, that was my concern with sharding across ~10 domains. I think the reason why we don't hear about it is because very few people are sharding, and those that are usually only shard across 2-4 domains where CPU utilization is probably not an issue. Not to mention the fact that you basically have no visibility into the CPU of your clients' machines unless you are using something like WebPagetest.
There is visibility on the cpu usage of a browser (though not at the webpage level) through the browser providers/reputation/forums. Take for example the issues that get raised with Mozilla firefox about memory usage and stability. Whilst i appreciate that extreme sharding is going to be rare I cannot (anecdotally) remember seeing cpu usage being raised as a major concern for browsers. The cpu utilisation for creating connections and handling the streams from downloads (even 50-60) i would suggest is minor compared with parsing & executing the JS and CSS for the page. I had thought there used to be an option on webpagetest to set the number of connections that a browser made for a test cycle and was going to run a test to see the cpu load but I can't find it anymore....memory obviously playing tricks...time for the check :-)
(08-05-2010 05:10 AM)jklein Wrote:  Even if you run a complex ecommerce site 80-100 resources per page is on the high side
I agree that it is high but it is something I've seen all to often.

(08-05-2010 05:10 AM)jklein Wrote:  I don't have any data on this, but I'm guessing that intentionally adding a blocking resource just to allow a DNS lookup to be performed isn't a great idea. If you already have a blocking file at the top of the page though then it probably wouldn't hurt to use the CNAME hack and make that first DNS lookup fetch back the rest of the static domains on your page.
If you are using a single host to serve content or a hiding behind a loadbalancer then the html document is your blocking resource that can grab all the DNS aliases when utilising the CNAME hack.
Some people are placing dummy link elements in their html head to try and force a browser DNS prefetch, though this won't work very well in a non-blocking parallel download world.
I was thinking along the links of a script element that attempted to download an image from a webserver that would serve a 204 response. so you would pay the price of the lookup and creating a connection but wouldn't get hit by tcp slow start as the response would fit in the first tcp window. placing this as the first element to be downloaded would hopefully initiate the desired DNS fetch making the records/aliases available for the other connections down the line. you could flush the head of the html document to mitigate the blocking nature of the element.
Again the future is brighter with browser DNS prefetch coming along in future browsers, and i think it is there to some degree in some of the current ones.
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Messages In This Thread
RE: Inline JavaScript Experiment - pmeenan - 07-10-2010, 02:50 AM
RE: Inline JavaScript Experiment - pmeenan - 07-10-2010, 05:33 AM
RE: Inline JavaScript Experiment - pmeenan - 07-11-2010, 01:42 AM
RE: Inline JavaScript Experiment - sajal - 07-12-2010, 08:04 AM
RE: Inline JavaScript Experiment - pmeenan - 07-12-2010, 02:19 AM
RE: Inline JavaScript Experiment - jklein - 07-13-2010, 12:19 AM
RE: Inline JavaScript Experiment - jklein - 08-05-2010, 05:10 AM
RE: Inline JavaScript Experiment - calumfodder - 08-11-2010 04:59 AM
RE: Inline JavaScript Experiment - pmeenan - 08-11-2010, 05:05 AM
RE: Inline JavaScript Experiment - jklein - 07-13-2010, 12:49 AM
RE: Inline JavaScript Experiment - pmeenan - 07-13-2010, 05:42 AM
RE: Inline JavaScript Experiment - pmeenan - 07-13-2010, 09:09 AM

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