[14:18:48] <Krinkle>	 tgr|away: with https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CommonsMetadata/+/983714/ do you mean this change would introduce a second parser run?
[14:19:11] <Krinkle>	 I assumed it piggy backed on the canonical parse that is there regardless.
[14:20:19] <Krinkle>	 on preview, it gives you what your personal settings would result in (which we don't save to PC), and on save MW core already does 2 parses if you have non-default parser options regardless of any extension hook (one to warm up PC for your page view, and one for LinksUpdate).
[22:34:43] <tgr>	 Krinkle: not the wikitext parser, just CommonsMetadata's own parsing of the HTML.
[22:36:42] <tgr>	 and it's not related to the change - I was just saying that we are doing a lot of unnecessary parses by running the DataCollector code after every wikitext parse when it's only used after the canonical parse.
[22:40:44] <tgr>	 They aren't very expensive (there's a HTML -> DOM parse via libxml and then some fairly trivial tree traversal) so it's not a huge deal.
[22:42:29] <tgr>	 I guess not seeing the tracking categories on preview would be annoying.