Since we upgraded to MediaWiki v1.22 we've been having intermittent performance issues on some pages with many images/thumbnails. After a bunch of poking around it seems to be due to thumbnails not being saved to disk. It seems they are saved to a cache (assumably memcached) so the first load a user does is slow and then it is fine for about a day.
As an example we have this page: http://content3.uesp.net/wiki/Online:Ardent_Flame On a "normal" logged-in session load the page takes 0.5 seconds for the article to load. However, on a slow load it takes 8-10 seconds for the article to load. You can force this to happen by doing a purge on the page (?action=purge). If we enable profiling/debug we see a bunch of lines like: File::transform: Doing stat for mwstore://local-backend/local-thumb/1/11/ON-icon-skill-Dragonknight-Dragonknight_Standard.png/48px-ON-icon-skill-Dragonknight-Dragonknight_Standard.png BitmapHandler::doTransform: creating 48x48 thumbnail at mwstore://local-backend/local-thumb/1/11/ON-icon-skill-Dragonknight-Dragonknight_Standard.png/48px-ON-icon-skill-Dragonknight-Dragonknight_Standard.png using scaler im BitmapHandler::doTransform: Transforming later per flags. (see http://www.uesp.net/wiki/User:Daveh/TestProfile1 for more). The strange thing is that a lot of these thumbnails files already exist so I don't understand why they're being created. For thumbnails that don't exist we see lines like: FileBackendStore::getFileStat: File mwstore://local-backend/local-thumb/b/b4/ON-icon-ActiveFrame.png/64px-ON-icon-ActiveFrame.png does not exist. BitmapHandler::doTransform: creating 64x64 thumbnail at /home/uesp/www/wtest/images/tmp/transform_6fc8d30c9ff9-1.png using scaler im BitmapHandler::doTransform: returning unscaled image Unfortunately, the specified tmp file doesn't exist nor does the thumbnail file after the page is loaded. A few "obvious" things I've checked: - Thumbnail files/paths are all readable/writable by Apache - Apache error logs (nothing) - MediaWiki debug output (nothing obvious) Some of the performance issue for this page could be also related to heavy use of templates but I'd like to figure out the thumbnail issue and rule it out as a cause first. A few specific questions: 1) Why are thumbnails being created that already exist? 2) Why are thumbnails not being created that don't exist, either as a tmp file or thumbnail file? 3) What does "Transforming later per flags." mean? When is "later"? Any help or suggestions would be welcome...Thanks! -- Dave Humphrey -- [email protected] Founder/Server Admin of the Unofficial Elder Scrolls Pages -- www.uesp.net www.viud.net - Building the world's toughest USB drive _______________________________________________ MediaWiki-l mailing list To unsubscribe, go to: https://lists.wikimedia.org/mailman/listinfo/mediawiki-l
