Latency metrics for getPageHTML on hewiki show a degradation from about 100ms at the beginning of March to about 800ms at the beginning of April: https://grafana.wikimedia.org/goto/14eNAfEVz?orgId=1 (note that the graph is log scale, and shows a one-day running average).
Note that hewiki is one of the wikis where we have been testing VisualEditor in "direct" mode: access to Parsoid is done by direct calls to PHP methods and makes use of ParserCache, instead of going through RESTbase.
Analysis:
- Local testing vith a vanilla setup shows the parser cache to be used as expected
- The ParserCache does not seem to be utilized in production. Analyzing the xhprof output of the following API call indicates that the page is re-parsed every time: https://he.wikipedia.org/w/api.php?action=visualeditor&format=json&paction=parse&page=%D7%94%D7%A7%D7%95%D7%98%D7%91_%D7%94%D7%93%D7%A8%D7%95%D7%9E%D7%99&uselang=he&editintro=&preload=&formatversion=2
- The debug log says: Parser options are not safe to cache and has not been saved
- The page view output however seems to be caceable: Saved in parser cache with key hewiki:pcache:idhash:18722-0!canonical and timestamp 20230418082705 and revision id 35665162. Rendering was triggered because: page-view