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Maniphest T296610

MediumSpecificBagOStuff->guessSerialValueSize infinite loop when storing Title object (Special:Homepage throws "Maximum function nesting reached")
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Description

Special:Homapage errors out with

[a3777da0e7bef2b536b810f3] /w/index.php?title=Special:Homepage&source=personaltoolslink&namespace=-1 Error: Maximum function nesting level of '200' reached, aborting!

Backtrace:

from /vagrant/mediawiki/includes/libs/objectcache/MediumSpecificBagOStuff.php(1028)
#0 /vagrant/mediawiki/includes/libs/objectcache/MediumSpecificBagOStuff.php(1063): MediumSpecificBagOStuff->guessSerialValueSize(Closure, integer, integer)
...
#173 /vagrant/mediawiki/includes/libs/objectcache/MediumSpecificBagOStuff.php(1063): MediumSpecificBagOStuff->guessSerialValueSize(Closure, integer, integer)
#174 /vagrant/mediawiki/includes/libs/objectcache/MediumSpecificBagOStuff.php(1063): MediumSpecificBagOStuff->guessSerialValueSize(array, integer, integer)
#175 /vagrant/mediawiki/includes/libs/objectcache/MediumSpecificBagOStuff.php(1063): MediumSpecificBagOStuff->guessSerialValueSize(array, integer, integer)
#176 /vagrant/mediawiki/includes/libs/objectcache/MediumSpecificBagOStuff.php(1063): MediumSpecificBagOStuff->guessSerialValueSize(Title, integer, integer)
#177 /vagrant/mediawiki/includes/libs/objectcache/MediumSpecificBagOStuff.php(1063): MediumSpecificBagOStuff->guessSerialValueSize(GrowthExperiments\NewcomerTasks\Task\Task, integer, integer)
#178 /vagrant/mediawiki/includes/libs/objectcache/MediumSpecificBagOStuff.php(1063): MediumSpecificBagOStuff->guessSerialValueSize(array, integer, integer)
#179 /vagrant/mediawiki/includes/libs/objectcache/MemcachedPeclBagOStuff.php(281): MediumSpecificBagOStuff->guessSerialValueSize(GrowthExperiments\NewcomerTasks\Task\TaskSet)
#180 /vagrant/mediawiki/includes/libs/objectcache/wancache/WANObjectCache.php(1873): MemcachedPeclBagOStuff->setNewPreparedValues(array)
#181 /vagrant/mediawiki/includes/libs/objectcache/wancache/WANObjectCache.php(1710): WANObjectCache->checkAndSetCooloff(string, string, GrowthExperiments\NewcomerTasks\Task\TaskSet, double, boolean)
#182 /vagrant/mediawiki/includes/libs/objectcache/wancache/WANObjectCache.php(1518): WANObjectCache->fetchOrRegenerate(string, integer, Closure, array, array)
#183 /vagrant/mediawiki/extensions/GrowthExperiments/includes/NewcomerTasks/TaskSuggester/CacheDecorator.php(181): WANObjectCache->getWithSetCallback(string, integer, Closure, array)
#184 /vagrant/mediawiki/extensions/GrowthExperiments/includes/NewcomerTasks/TaskSuggester/QualityGateDecorator.php(69): GrowthExperiments\NewcomerTasks\TaskSuggester\CacheDecorator->suggest(User, array, array, integer, NULL, array)
#185 /vagrant/mediawiki/extensions/GrowthExperiments/includes/HomepageModules/SuggestedEdits.php(402): GrowthExperiments\NewcomerTasks\TaskSuggester\QualityGateDecorator->suggest(User, array, array, NULL, NULL, array)
#186 /vagrant/mediawiki/extensions/GrowthExperiments/includes/HomepageModules/SuggestedEdits.php(802): GrowthExperiments\HomepageModules\SuggestedEdits->getTaskSet()
#187 /vagrant/mediawiki/extensions/GrowthExperiments/includes/HomepageModules/BaseModule.php(165): GrowthExperiments\HomepageModules\SuggestedEdits->getActionData()
#188 /vagrant/mediawiki/extensions/GrowthExperiments/includes/DashboardModule/DashboardModule.php(184): GrowthExperiments\HomepageModules\BaseModule->outputDependencies()
#189 /vagrant/mediawiki/extensions/GrowthExperiments/includes/Specials/SpecialHomepage.php(325): GrowthExperiments\DashboardModule\DashboardModule->render(string)
#190 /vagrant/mediawiki/extensions/GrowthExperiments/includes/Specials/SpecialHomepage.php(267): GrowthExperiments\Specials\SpecialHomepage->getModuleRenderHtmlSafe(GrowthExperiments\HomepageModules\SuggestedEdits, string)
#191 /vagrant/mediawiki/extensions/GrowthExperiments/includes/Specials/SpecialHomepage.php(137): GrowthExperiments\Specials\SpecialHomepage->renderDesktop()
#192 /vagrant/mediawiki/includes/specialpage/SpecialPage.php(647): GrowthExperiments\Specials\SpecialHomepage->execute(NULL)
#193 /vagrant/mediawiki/includes/specialpage/SpecialPageFactory.php(1375): SpecialPage->run(NULL)
#194 /vagrant/mediawiki/includes/MediaWiki.php(314): MediaWiki\SpecialPage\SpecialPageFactory->executePath(string, RequestContext)
#195 /vagrant/mediawiki/includes/MediaWiki.php(910): MediaWiki->performRequest()
#196 /vagrant/mediawiki/includes/MediaWiki.php(554): MediaWiki->main()
#197 /vagrant/mediawiki/index.php(53): MediaWiki->run()
#198 /vagrant/mediawiki/index.php(46): wfIndexMain()
#199 /var/www/w/index.php(5): require(string)
#200 {main}

Apparently MediumSpecificBagOStuff->guessSerialValueSize tries to traverse the cached object, and gets into an infinite loop inside the Title contained in TaskSet (Title -> deprecatedPublicProperties -> mTextform -> Closure -> Title).

Not sure if this affects production (MediumSpecificBagOStuff->guessSerialValueSize has some logic to abort after 256 levels so depends on how much nesting is allowed) Also not sure why I'm only seeing this error now, none of the affected code is new. In any case, TaskSet should probably be JsonSerializable, so that a JSON-ish representation is serialized instead of the full object, per T161647: RFC: Deprecate using php serialization inside MediaWiki.

Details

Related Changes in Gerrit:
SubjectRepoBranchLines +/-
Improve the performance of guessSerialValueSize()mediawiki/coremaster+5 -40
CacheDecorator: Use JSON serializationmediawiki/extensions/GrowthExperimentsmaster+60 -10
NewcomerTasks: Make value objects JSON-serializablemediawiki/extensions/GrowthExperimentsmaster+343 -8
Customize query in gerrit

Related Objects

Event Timeline

Tgr created this task.Nov 29 2021, 6:42 AM
Restricted Application added projects: Growth-Team, Performance-Team. · View Herald TranscriptNov 29 2021, 6:42 AM
Restricted Application added a subscriber: Aklapper. · View Herald Transcript
kostajh subscribed.Nov 29 2021, 7:53 AM

@Tgr are you still seeing this? I don't see it on enwiki beta. T296508: ERROR @wdio/sync: Error: socket hang up looks similar.

• dpifke assigned this task to aaron.Nov 29 2021, 7:49 PM
• dpifke moved this task from Inbox, needs triage to Doing: Prio Interrupt on the Performance-Team board.
Tgr added a comment.EditedNov 30 2021, 3:32 AM
In T296610#7533006, @kostajh wrote:

@Tgr are you still seeing this? I don't see it on enwiki beta. T296508: ERROR @wdio/sync: Error: socket hang up looks similar.

The hoomepage on my local setup is permanently broken because of this. I think production has some perversely high nesting limit because of something that Parsoid does, so it wouldn't be affected. It would be easy to configure around this locally, but

  1. seems not ideal for performance (I wonder if the loop condition was meant to be an OR instead of an AND, that would seem more natural to me)
  2. we should avoid serializing PHP objects anyway, so we might as well fix this.
gerritbot added a comment.Nov 30 2021, 6:57 AM

Change 742591 had a related patch set uploaded (by Gergő Tisza; author: Gergő Tisza):

[mediawiki/extensions/GrowthExperiments@master] NewcomerTasks: Make value objects JSON-serializable

https://gerrit.wikimedia.org/r/742591

gerritbot added a project: Patch-For-Review.Nov 30 2021, 6:57 AM

Change 742594 had a related patch set uploaded (by Gergő Tisza; author: Gergő Tisza):

[mediawiki/extensions/GrowthExperiments@master] [WIP] CacheDecorator: Use JSON serialization

https://gerrit.wikimedia.org/r/742594

Tgr moved this task from Inbox to Triaged on the Growth-Team board.Dec 1 2021, 3:05 AM
Tgr added a comment.Dec 1 2021, 6:14 AM
In T296610#7536377, @Tgr wrote:

I think production has some perversely high nesting limit because of something that Parsoid does

I had a vague recollection that fastcgi has nesting limits, but that doesn't seem to be the case, so the error would only happen with XDebug installed.

It would be easy to configure around this locally

FTR that's xdebug.max_nesting_level=300 in some PHP ini file.

gerritbot added a comment.Dec 1 2021, 7:02 PM

Change 742591 merged by jenkins-bot:

[mediawiki/extensions/GrowthExperiments@master] NewcomerTasks: Make value objects JSON-serializable

https://gerrit.wikimedia.org/r/742591

ReleaseTaggerBot added a project: MW-1.38-notes (1.38.0-wmf.12; 2021-12-06).Dec 1 2021, 8:00 PM
gerritbot added a comment.Dec 13 2021, 9:42 PM

Change 742594 merged by jenkins-bot:

[mediawiki/extensions/GrowthExperiments@master] CacheDecorator: Use JSON serialization

https://gerrit.wikimedia.org/r/742594

Maintenance_bot removed a project: Patch-For-Review.Dec 13 2021, 10:11 PM
aaron triaged this task as Medium priority.Jan 7 2022, 1:42 AM
gerritbot added a comment.Jan 18 2022, 7:12 AM

Change 754856 had a related patch set uploaded (by Aaron Schulz; author: Aaron Schulz):

[mediawiki/core@master] objectcache: fix guessSerialValueSize() for complex objects

https://gerrit.wikimedia.org/r/754856

gerritbot added a project: Patch-For-Review.Jan 18 2022, 7:12 AM
tstarling subscribed.Jan 20 2022, 12:39 AM

Was any benchmarking done to support the introduction of this feature? There was no linked bug on https://gerrit.wikimedia.org/r/c/mediawiki/core/+/580607 . I'm having trouble trying to find a test case for which it is faster than json_encode().

> $prefixes = svc('InterwikiLookup')->getAllPrefixes();
> print count($prefixes);
67
> $t = microtime(true); for ( $i = 0; $i < 100000; $i++ ) { $cache->guessSerialValueSize($prefixes); } print microtime(true)-$t;
6.735631942749
> $t = microtime(true); for ( $i = 0; $i < 100000; $i++ ) { json_encode($prefixes); } print microtime(true)-$t;
3.0343141555786
> $s = str_repeat('x',1000);
> $t = microtime(true); for ( $i = 0; $i < 100000; $i++ ) { $cache->guessSerialValueSize($s); } print microtime(true)-$t;
0.088092088699341
> $t = microtime(true); for ( $i = 0; $i < 100000; $i++ ) { json_encode($s); } print microtime(true)-$t;
0.082571983337402
> $a = new stdClass;
> $a = [ &$a, &$a ];
> $t = microtime(true); for ( $i = 0; $i < 100000; $i++ ) { $cache->guessSerialValueSize($a); } print microtime(true)-$t;
0.36614179611206
> $t = microtime(true); for ( $i = 0; $i < 100000; $i++ ) { json_encode($a); } print microtime(true)-$t;
0.011312961578369

This is including the patch above.

gerritbot added a comment.Jan 20 2022, 1:00 AM

Change 755517 had a related patch set uploaded (by Tim Starling; author: Tim Starling):

[mediawiki/core@master] Improve the performance of guessSerialValueSize()

https://gerrit.wikimedia.org/r/755517

Krinkle moved this task from General to libs/objectcache on the MediaWiki-libs-BagOStuff board.Jan 21 2022, 9:36 PM
Krinkle renamed this task from Special:Homepage throws "Maximum function nesting level of '200' reached, aborting!" to MediumSpecificBagOStuff->guessSerialValueSize infinite loop when storing Title object (Special:Homepage throws "Maximum function nesting reached").Jan 21 2022, 9:39 PM
Krinkle moved this task from libs/objectcache to General on the MediaWiki-libs-BagOStuff board.Jan 22 2022, 11:24 PM
gerritbot added a comment.Jan 25 2022, 11:54 PM

Change 755517 merged by jenkins-bot:

[mediawiki/core@master] Improve the performance of guessSerialValueSize()

https://gerrit.wikimedia.org/r/755517

ReleaseTaggerBot edited projects, added MW-1.38-notes (1.38.0-wmf.20; 2022-01-31); removed MW-1.38-notes (1.38.0-wmf.12; 2021-12-06).Jan 26 2022, 12:00 AM
aaron closed this task as Resolved.Jan 26 2022, 10:56 PM
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