action=info times out with an unfriendly error message on certain pages
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Description

Go to a page like https://en.wikipedia.org/wiki/Wikipedia:Sandbox?action=info. The following message appears, without any skin interface:

A database query error has occurred. This may indicate a bug in the software.

    Function: InfoAction::pageCounts
    Error: 2013 Lost connection to MySQL server during query (10.64.48.27)

Presumably what this really means is that some sort of internal timeout has occurred.

Ideally the error should be reported in a more friendly fashion. It is not, after all, a "bug in the software" that the error occurs; it's just a DB timeout.

Or, even better, handle these internal timeouts more cleanly and just present the action=info page without the unavailable information.

Details

	Project	Branch	Lines +/-	Subject
	mediawiki/core	master	+6 -5	InfoAction: Use watchlist query group for watchlist queries

Customize query in gerrit

Related Objects

Mentioned In: rMWa2e0bf218649: InfoAction: Use watchlist query group for watchlist queries
T51506: Implement "actual watchers" count into MediaWiki's info action
T67332: InfoAction::pageCounts makes slow query based on rev_user_text (use rev_use instead?)
Mentioned Here: T67332: InfoAction::pageCounts makes slow query based on rev_user_text (use rev_use instead?)

Event Timeline

TTO created this task.Jul 15 2015, 2:34 AM

TTO raised the priority of this task from to Needs Triage.

TTO updated the task description. (Show Details)

TTO added projects: Wikimedia-production-error, MediaWiki-General.

TTO added a subscriber: TTO.

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptJul 15 2015, 2:34 AM

Maybe T67332 is the underlying bug?

I think we have a long running query killer. So handling better would be a good start

MZMcBride added a subscriber: MZMcBride.Jul 15 2015, 2:40 AM

demon triaged this task as Medium priority.Jul 15 2015, 2:41 AM

demon moved this task from Untriaged to Dec 2019 / 1.35.wmf.10+ on the Wikimedia-production-error board.

MZMcBride mentioned this in T67332: InfoAction::pageCounts makes slow query based on rev_user_text (use rev_use instead?).Jul 15 2015, 2:51 AM

Nemo_bis mentioned this in T51506: Implement "actual watchers" count into MediaWiki's info action.Jul 15 2015, 8:39 AM

Ricordisamoa added a subscriber: Ricordisamoa.Jul 15 2015, 2:31 PM

Does this happen anywhere outside en.wiki, by the way? The English Wikipedia is special because it has a separate server for watchlist queries (as IIRC no other one has). Are we using it when appropriate? Is 10.64.48.27 that one?

Nemo_bis edited projects, added Wikimedia-Rdbms; removed MediaWiki-General.Jul 16 2015, 8:17 AM

Nemo_bis set Security to None.

Umherirrender added subscribers: Springle, greg.Jul 16 2015, 7:33 PM

In T105852#1456476, @Nemo_bis wrote:

Does this happen anywhere outside en.wiki, by the way? The English Wikipedia is special because it has a separate server for watchlist queries (as IIRC no other one has). Are we using it when appropriate? Is 10.64.48.27 that one?

10.64.48.27 = db1072, but s1's server with watchlist listed in wmf-config/db-eqiad.php is db1055 (10.64.32.25).
We're not using that specific group for watchlist queries in action=info. I'll upload a patch to do that.

Change 225227 had a related patch set uploaded (by Alex Monk):
InfoAction: Use watchlist query group for watchlist queries

https://gerrit.wikimedia.org/r/225227

gerritbot added a project: Patch-For-Review.Jul 16 2015, 8:43 PM

Change 225227 merged by jenkins-bot:
InfoAction: Use watchlist query group for watchlist queries

https://gerrit.wikimedia.org/r/225227

Krenair mentioned this in rMWa2e0bf218649: InfoAction: Use watchlist query group for watchlist queries.Jul 16 2015, 9:41 PM

Forrestbot added projects: MW-1.26-release, WMF-deploy-2015-07-21_(1.26wmf15).Jul 16 2015, 10:00 PM

Do we just want to leave this open and see if the situation improves when this arrives on wikipedias?

Krenair removed a project: Patch-For-Review.Jul 16 2015, 10:22 PM

Thank for the quick patch! Yes, no hurry to close.

Bawolff added a subscriber: Bawolff.Jul 18 2015, 10:22 AM

The situation is no different to before. Did the patch really go out with 1.26wmf15?

Yep.

Elitre added a subscriber: Elitre.Jul 29 2015, 3:55 PM

Glaisher added a subscriber: Glaisher.Sep 5 2015, 3:51 PM

Seems to work properly now! It was kinda slow the first time I visited https://en.wikipedia.org/wiki/Wikipedia:Sandbox?action=info, but subsequently it is very fast. I wonder what changed?

Interesting indeed, several other pathological cases seem fine too now. Curiously, just yesterday we had

10:41 jynus: potential extra load on mediawiki recent changes and watchlist on enwiki, please report any slowdown

demon moved this task from Dec 2019 / 1.35.wmf.10+ to Resolved on the Wikimedia-production-error board.Oct 26 2015, 4:37 PM

action=info times out with an unfriendly error message on certain pagesClosed, ResolvedPublicActions

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action=info times out with an unfriendly error message on certain pages
Closed, ResolvedPublic
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