Last modified: 2014-04-29 15:00:46 UTC
Currently, I believe the API has little throttling built in (if any). This can cause problems if people or organizations are hitting the API with expensive queries at a fast rate. Bug filed in response to ExternalStorage issues from &rvprop=content|timestamp being batch queried from the API. Some sort of sensible options should be implemented to throttle expensive queries with variables to override the defaults for very robust or very weak servers.
I don't believe this is a general API issue, but rather a MediaWiki or Wikimedia issue. Batch-querying rvprop=content is one way to cause an ES hiccup, but there are others, like hitting Special:Export at the same rate; the latter would actually be much more effective at killing ES servers, because it'll happily export an unlimited number of revisions of a single page (and an unlimited number of pages too, IIRC, so you could potentially ask Special:Export to try to export the entire wiki at once), whereas the API is limited to 50 content fetches per request (500 for bots/sysops).
INVALID, not an API bug.
Re-opening with an expanded scope. Changed summary from "API needs better throttling for expensive queries" to "MediaWiki needs better throttling for expensive queries." This is definitely an issue that needs to be addressed at some point.
Bringing in performance-savvy contributors to weigh in in this old request. Marking as Lowest, since nobody seems to be working or planning to work on this currently.