PHP Warning: Illegal string offset 'page_len'
Closed, ResolvedPublicPRODUCTION ERROR
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	Lucas_Werkmeister_WMDE
	Mar 12 2024, 1:56 PM

Description

Error

mwversion: 1.42.0-wmf.22
reqId: 562cddc3-ce4b-4a60-bf9f-d98517fee31e
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normalized_message

[{reqId}] {exception_url}   PHP Warning: Illegal string offset 'page_len'

exception.trace

from /srv/mediawiki/php-1.42.0-wmf.22/includes/ResourceLoader/WikiModule.php(484)
#0 /srv/mediawiki/php-1.42.0-wmf.22/includes/ResourceLoader/WikiModule.php(484): MWExceptionHandler::handleError(integer, string, string, integer, array)
#1 /srv/mediawiki/php-1.42.0-wmf.22/includes/Output/OutputPage.php(3485): MediaWiki\ResourceLoader\WikiModule->isKnownEmpty(MediaWiki\ResourceLoader\Context)
#2 [internal function]: MediaWiki\Output\OutputPage::MediaWiki\Output\{closure}(string)
#3 /srv/mediawiki/php-1.42.0-wmf.22/includes/Output/OutputPage.php(3493): array_filter(array, Closure)
#4 /srv/mediawiki/php-1.42.0-wmf.22/includes/Output/OutputPage.php(3544): MediaWiki\Output\OutputPage->getRlClient()
#5 /srv/mediawiki/php-1.42.0-wmf.22/includes/skins/SkinMustache.php(98): MediaWiki\Output\OutputPage->headElement(MediaWiki\Skins\Vector\SkinVector22)
#6 /srv/mediawiki/php-1.42.0-wmf.22/includes/skins/SkinTemplate.php(176): SkinMustache->generateHTML()
#7 /srv/mediawiki/php-1.42.0-wmf.22/includes/Output/OutputPage.php(3004): SkinTemplate->outputPage()
#8 /srv/mediawiki/php-1.42.0-wmf.22/includes/actions/ActionEntryPoint.php(162): MediaWiki\Output\OutputPage->output(boolean)
#9 /srv/mediawiki/php-1.42.0-wmf.22/includes/MediaWikiEntryPoint.php(199): MediaWiki\Actions\ActionEntryPoint->execute()
#10 /srv/mediawiki/php-1.42.0-wmf.22/index.php(58): MediaWiki\MediaWikiEntryPoint->run()
#11 /srv/mediawiki/w/index.php(3): require(string)
#12 {main}

Impact

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Notes

First seen Mar 12, 2024 @ 04:01:30.096. So far only observed on three wikis: www.mediawiki.org, test.wikipedia.org, and office.wikimedia.org. (All three are in group0, but they’re hardly the only group0 wikis, so this still seems a bit unexpected.)

Details

Request URL: https://www.mediawiki.org/wiki/MediaWiki

	Subject	Repo	Branch	Lines +/-
	WikiModule: Fix data structure when preloading title info	mediawiki/core	wmf/1.42.0-wmf.22	+1 -1
	WikiModule: Fix data structure when preloading title info	mediawiki/core	master	+1 -1

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		Status	Subtype	Assigned	Task
		Resolved	Release	hashar	T354440 1.42.0-wmf.22 deployment blockers
		Resolved	PRODUCTION ERROR	matmarex	T359939 PHP Warning: Illegal string offset 'page_len'

Event Timeline

Lucas_Werkmeister_WMDE created this task.Mar 12 2024, 1:56 PM

Restricted Application added a project: MediaWiki-Platform-Team. · View Herald TranscriptMar 12 2024, 1:56 PM

Restricted Application added a subscriber: Aklapper. · View Herald Transcript

Lucas_Werkmeister_WMDE mentioned this in T354440: 1.42.0-wmf.22 deployment blockers.Mar 12 2024, 1:58 PM

hashar added a parent task: T354440: 1.42.0-wmf.22 deployment blockers.Mar 12 2024, 2:01 PM

Marking as Unbreak Now! since I don't quite know the impact that might have. The code path refers to SkinVector22, then includes/ResourceLoader/WikiModule.php had some patches introduced in 1.42.0-wmf.22 for T359522:

rMW3903c8cfecce: ResourceLoader: Migrate wfGetDB call to ICP and move to WikiModule
rMW6194cf19ce73: ResourceLoader: Add preload for foreign WikiModule title info

Then looking a bit more at WikiModule.php, the page_len is not necessarily always set but I don't know that code base at all :-(

Looking at other messages, the stacktrace refers to other skins as well such as SkinVectorLegacy, SkinMustache or SkinTimeless. That thus does not seem to be specific to Vector 2022.

In T359939#9623600, @hashar wrote:

rMW3903c8cfecce: ResourceLoader: Migrate wfGetDB call to ICP and move to WikiModule
rMW6194cf19ce73: ResourceLoader: Add preload for foreign WikiModule title info

CC @Krinkle as the author of those patches (though he’s not the only one to have touched RL this train).

I spent a few minutes re-reading the code, and I think page_len is always set, but the titleInfo array we're building in that code is multi-dimensional, and we got confused about which level we're on.

Change 1010532 had a related patch set uploaded (by Bartosz Dziewoński; author: Bartosz Dziewoński):

[mediawiki/core@master] WikiModule: Fix data structure when preloading title info

https://gerrit.wikimedia.org/r/1010532

gerritbot added a project: Patch-For-Review.Mar 12 2024, 2:51 PM

(I won't have the time today to backport this, I hope someone else can do it.)

Great thank you for digging into it and figuring out the cause. I'd let Timo review/approve the fix then I guess he can backport/deploy it. Else I will do it later tonight.

Change 1010532 merged by jenkins-bot:

[mediawiki/core@master] WikiModule: Fix data structure when preloading title info

https://gerrit.wikimedia.org/r/1010532

Maintenance_bot removed a project: Patch-For-Review.Mar 12 2024, 4:30 PM

ReleaseTaggerBot added a project: MW-1.42-notes (1.42.0-wmf.23; 2024-03-19).Mar 12 2024, 5:00 PM

Change 1010568 had a related patch set uploaded (by Jforrester; author: Bartosz Dziewoński):

[mediawiki/core@wmf/1.42.0-wmf.22] WikiModule: Fix data structure when preloading title info

https://gerrit.wikimedia.org/r/1010568

gerritbot added a project: Patch-For-Review.Mar 12 2024, 6:29 PM

Change 1010568 merged by jenkins-bot:

[mediawiki/core@wmf/1.42.0-wmf.22] WikiModule: Fix data structure when preloading title info

https://gerrit.wikimedia.org/r/1010568

Mentioned in SAL (#wikimedia-operations) [2024-03-12T19:45:31Z] <hashar@deploy2002> Started scap: Backport for [[gerrit:1010568|WikiModule: Fix data structure when preloading title info (T359939)]]

Mentioned in SAL (#wikimedia-operations) [2024-03-12T19:47:57Z] <hashar@deploy2002> hashar and jforrester: Backport for [[gerrit:1010568|WikiModule: Fix data structure when preloading title info (T359939)]] synced to the testservers (https://wikitech.wikimedia.org/wiki/Mwdebug)

Mentioned in SAL (#wikimedia-operations) [2024-03-12T19:58:46Z] <hashar@deploy2002> Finished scap: Backport for [[gerrit:1010568|WikiModule: Fix data structure when preloading title info (T359939)]] (duration: 13m 14s)