Aryeh Gregor wrote: > On Thu, Jun 25, 2009 at 8:14 PM, Domas Mituzas<[email protected]> wrote: >> The problem is quite simple, lots of people (like, million pageviews >> on an article in an hour) caused a cache stampede (all pageviews >> between invalidation and re-rendering needed parsing), and as MJ >> article is quite cite-heavy (and cite problems were outlined in >> http://article.gmane.org/gmane.science.linguistics.wikipedia.technical/41547 >> ;) the reparsing was very very painful on our application cluster - >> all apache children eventually ended up doing lots of parsing work and >> consuming connection slots to pretty much everything :) > > So if two page views are trying to view the same uncached page at the > same time with the same settings, the later ones should all block on > the first one's reparsing instead of doing it themselves. It should > provide faster service for big articles too, even ignoring load, since > the earlier parse will be done before you could finish yours anyway.
It's quite a complex feature. If you have a server that deadlocks or is otherwise extremely slow, then it will block rendering for all other attempts, meaning that the article can not be viewed at all. That scenario could even lead to site-wide downtime, since threads waiting for the locks could consume all available apache threads, or all available DB connections. It's a reasonable idea, but implementing it would require a careful design, and possibly some other concepts like per-article thread count limits. -- Tim Starling _______________________________________________ Wikitech-l mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/wikitech-l
