This appears to be about a diagnostic message logged in the GlobalPreferences channel by GlobalPreferencesFactory.php. This is not a production error, untagging as such. This is not a statement of severity, just of category. There are plenty of tasks that represent important bugs or tech debt that aren't prod errors.

Hi, does this still happen frequently these days?
It's weird that an error that can cause a great difference in the appearance of UI is suppressed to a warning in advance. T302627 can be caused by this.

In T285216#7802539, @Func wrote:

Hi, does this still happen frequently these days?

It does, I see about 1.4k entries in the last 15 minutes.

Tag MediaWiki-extensions-CentralAuth since the lookup is implemented in it.

As far as I can tell the CentralIdLookup API offered by CentralAuth works fine:

taavi@mwmaint1002 ~ $ mwscript shell.php enwiki
Psy Shell v0.11.1 (PHP 7.2.34-18+0~20210223.60+debian10~1.gbpb21322+wmf5 — cli) by Justin Hileman
>>> $lookup = \MediaWiki\MediaWikiServices::getInstance()->getCentralIdLookupFactory()->getLookup();
=> MediaWiki\Extension\CentralAuth\User\CentralAuthIdLookup {#3323}
>>> $lookup->centralIdFromLocalUser( User::newFromName( 'Majavah' ), CentralIdLookup::AUDIENCE_RAW );
=> 57461233

Hmm, all of the requests I just checked on logstash with this warning were new account creations. Maybe some race condition somewhere?

In T285216#7806550, @Majavah wrote:

Hmm, all of the requests I just checked on logstash with this warning were new account creations. Maybe some race condition somewhere?

Just in the same request of new account creations? Maybe we can filter out them by handling the LocalUserCreated hook, since looking for new users' preference don't make much sense. Then we can see if there are any remaining warnings for old accounts mentioned in the task description.

Change 773904 had a related patch set uploaded (by Func; author: Func):

[mediawiki/extensions/GlobalPreferences@master] Avoid unnecessary calls to fetching global preferences

https://gerrit.wikimedia.org/r/773904

Change 773904 merged by jenkins-bot:

[mediawiki/extensions/GlobalPreferences@master] Avoid unnecessary calls to fetching global preferences

https://gerrit.wikimedia.org/r/773904

Noting that the frequency of this warning dropped dramatically around June 30, once https://gerrit.wikimedia.org/r/773904 got to group2. However I still see thousands of entries each day, but they could have different causes: https://logstash.wikimedia.org/goto/b51177280bfcdd35ce6a2e95dbb038fe (this takes a while to load, FYI)

I was able to reproduce this locally by navigating to Special:Preferences with a central session but no local account. Early in the request, I got this stack trace:

• CentralAuthUser.php:2493, MediaWiki\Extension\CentralAuth\User\CentralAuthUser->loadAttached()
• CentralAuthUser.php:3177, MediaWiki\Extension\CentralAuth\User\CentralAuthUser->attachedOn()
• CentralAuthIdLookup.php:122, MediaWiki\Extension\CentralAuth\User\CentralAuthIdLookup->isAttached()
• CentralAuthIdLookup.php:129, MediaWiki\Extension\CentralAuth\User\CentralAuthIdLookup->centralIdFromLocalUser()
• GlobalPreferencesFactory.php:508, {closure:GlobalPreferencesFactory.php:506}()
• MapCacheLRU.php:271, MapCacheLRU->getWithSetCallback()
• GlobalPreferencesFactory.php:509, GlobalPreferences\GlobalPreferencesFactory->getUserID()
• GlobalPreferencesFactory.php:494, GlobalPreferences\GlobalPreferencesFactory->isUserGlobalized()
• Hooks.php:86, GlobalPreferences\Hooks->onLoadUserOptions()
• HookContainer.php:159, MediaWiki\HookContainer\HookContainer->run()
• HookRunner.php:4313, MediaWiki\HookContainer\HookRunner->onLoadUserOptions()
• UserOptionsManager.php:676, MediaWiki\User\Options\UserOptionsManager->loadOriginalOptions()
• UserOptionsManager.php:452, MediaWiki\User\Options\UserOptionsManager->saveOptionsInternal()
• UserOptionsManager.php:421, MediaWiki\User\Options\UserOptionsManager->saveOptions()
• User.php:2757, MediaWiki\User\User->addToDatabase()
• AuthManager.php:1911, MediaWiki\Auth\AuthManager->autoCreateUser()
• Setup.php:585, require_once()
• WebStart.php:85, require()
• index.php:50, {main}()

Attachment is being queried while User::addToDatabase() is still in the stack. CentralAuth has not yet had a chance to do attachment. A global ID of zero is saved into GlobalPreferencesFactory::$centralIds and that cache is not cleared once the user is attached. So, later in the same request, the global ID is still zero and the warning is logged.

Change #1016078 had a related patch set uploaded (by Tim Starling; author: Tim Starling):

[mediawiki/extensions/GlobalPreferences@master] Remove central ID cache

https://gerrit.wikimedia.org/r/1016078

Change #1016078 merged by jenkins-bot:

[mediawiki/extensions/GlobalPreferences@master] Remove central ID cache

https://gerrit.wikimedia.org/r/1016078