Hi! >> That's pretty much the purpose of the caching servers. > > Yes, but I presume that a big advantage could come from having a > simplified, unique, js-free version of the pages online, completely devoid > of "user preferences" to avoid any need to parse it again when uploaded by > different users with different preferences profile. Nevertheless I say > again: it's only a completely layman idea.
I can a bit elaborate on what Daniel said. Whenever anyone edits a page, there're (simplistic view) of three caches that get populated. 1. Revision text cache (for operations like diffs, re-parsing for other settings, etc) 2. Parser cache (for logged in users) 3. Edge HTTP cache - squid (for anonymous users) So, anonymous users get "completely devoid of user preferences" pages, as they are simply defaults. Do note, even though squid cache objects can vary based on accept-encoding (we narrowed it down to two versions from 10 few years ago ;-), they map to single parser cache object. Parser cache hit may take under 50ms to deliver by backend mediawiki. Logged in users though bypass our squids, if they don't mess up with their preferences, usually hit same parser cache objects - there's an extremely high chance of that. Now, if you change single setting that affects parser cache variation, the 'extremely high chance' switches to missing those objects - as there has to be someone with same settings as you to visit it before. Delivering parser cache miss may take from 50ms to 50s, which is what jidanni probably hits. So, we may have 1000x slower performance for our users because they don't really know about our caching internals. Our only hope is that most of them are also ignorant that those settings exist ;-) There'd be of course another workaround - precaching objects for every variation, at extremely high cost for relatively low impact. Alternative is either having warning icon whenever people are in slow-perf mode that they'd be able to hide, or eliminating the choice (you know, the killing features business, that quite often works really well!!! ;-) Domas _______________________________________________ Wikitech-l mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/wikitech-l
