[Webkit-unassigned] [Bug 27165] Connections-per-host should be tracked closer to the ResourceHandle level, not the Cache

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=27165





--- Comment #18 from Antti Koivisto <koivisto at iki.fi>  2010-09-23 02:03:16 PST ---
(In reply to comment #17)
> > As far as I can see this patch wipes out the request prioritization in the Loader which is the whole purpose of throttling the requests in the first place.
> 
> Really?  I must have misunderstood how the prioritization works.

The idea is that Loader only issues a request to lower levels when there is a free pipe to the host available. New high priority resources can appear at any point of loading as a result of script execution or CSS parsing and we this way we can push these resources to the front of the queue.

With this patch ordering is done for resources found in a single runloop cycle only. Any high high priority resource (say script) found afterwards will end up at the end of the queue, loaded after all those 10MB images and delaying the first display for a minute.

> Losing the prioritization makes obviously doesn't make sense, but counting requests at the loader level is pretty non-sensical.  Notice that all the folks who are peers with loader have to do a crazy dance to interface with the connection limiter.
> 
> I suspect the right solution is to either to move the prioritization logic lower in the network stack or to teach the loader how to read back information about the state of the open connection limiter.

If all networking libraries would support per-host prioritization properly then we could just pass the priorities downward and wipe out most of the prioritization related code. That would be the elegant solution. I don't think that is true atm though.

What has been discussed, but not implemented yet, is that more loading (XHR, main document,..) should be happening through Loader instead of using ResourceLoaders directly. There would give other benefits too (memory caching, ability to cache parsed forms, validation support...)

Moving loading queues as well as the request counting to ResourceLoader level might indeed make sense.

Did this patch solve any concrete problems or is it purely about aesthetics?

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