Le 01/03/12 09:50, Jeroen De Dauw a écrit :
Hey,
There's been a slight regression in our parser cache hit rate: http://bit.ly/w6Gy9t
This one is probably more informative for people not aware of the usual hit rate http://goo.gl/YY80C
Looks to me that the miss rate went up over 500% - is that really just a "slight" regression? :)
We really want to use absolute time range: http://bit.ly/A7kcys
Anyway, they are absent misses. Probably a key changed somewhere in our parser that magically invalidated roughly 15% of the parser cache. It seems to slowly recover afterward.
By zooming and making the Y scale start at 50%, the event seems to have occurred on February 17th just before 6am UTC.
I have uploaded a screenshot on mediawiki.org :
https://www.mediawiki.org/wiki/File:Parser_cache_hit_20120217.png
From the wikitech admin logs we have:
07:42 binasher:upgraded mysql on db40 to 5.1.53-facebook-r3753, enabled innodb_use_purge_thread ---------------------------------------------------------------------- 05:39 tstarling synchronized wmf-config/InitialiseSettings.php 05:38 tstarling synchronized wmf-config/CommonSettings.php ---------------------------------------------------------------------- 05:35 Tim: on db40: reduced to 10M, should be causing massive delays, but the site's not down and the purge rate is lower if anything. Going to disable the mysql parser cache entirely. ---------------------------------------------------------------------- 05:25 Tim: on db40: purge lag is still increasing at 108 per second, so reducing innodb_max_purge_lag to 50M ---------------------------------------------------------------------- 05:21 Tim: on db40: giving the innodb manual the benefit of the doubt and following its advice, setting innodb_max_purge_lag to 100M, which should give a delay of 4.5ms ---------------------------------------------------------------------- 05:13 Tim: killing purgeParserCache.php since it is probably doing more harm than good ---------------------------------------------------------------------- 02:43 maplebed: deployed updated thumb_handler.php to ms5 to include Content-Length in generated images ---------------------------------------------------------------------- 02:34 logmsgbot: LocalisationUpdate completed (1.19) at Fri Feb 17 02:34:32 UTC 2012 ---------------------------------------------------------------------- https://wikitech.wikimedia.org/view/Server_admin_log
" Going to disable the mysql parser cache entirely."
Seems to have been reenabled on Feb 29th at 00:20:
00:20 Tim: reimported schema files on db40 and re-enabled mysql parser cache