Purge attempts for pages of files with large number of thumbnails fails on Commons
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	Ankry
	Jan 26 2019, 11:20 AM

Description

Purging a file:
https://commons.wikimedia.org/w/index.php?title=File:Jan_Syga%C5%84ski_-_Historya_Nowego_S%C4%85cza.djvu&action=purge
results in:

Service Temporarily Unavailable
Our servers are currently under maintenance or experiencing a technical problem. Please try again in a few minutes.

Sometimes can be seen a 503 error instead:

Error
Our servers are currently under maintenance or experiencing a technical problem. Please try again in a few minutes.
See the error message at the bottom of this page for more information.

If you report this error to the Wikimedia System Administrators, please include the details below.
Request from 89.64.57.243 via cp3033 cp3033, Varnish XID 479638527
Error: 503, Backend fetch failed at Sat, 26 Jan 2019 11:15:12 GMT

Same problem appears for other DjVu files with over 2000 active thumbnails.

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		Status	Subtype	Assigned	Task
		Open		None	T214759 Purge attempts for pages of files with large number of thumbnails fails on Commons
		Open		None	T186153 outdated DjVu file page thumbnail in cache

Event Timeline

Ankry created this task.Jan 26 2019, 11:20 AM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptJan 26 2019, 11:20 AM

Maybe also related to T206190 as there are thousands of outdated thumbnails related to this file.

Ankry updated the task description. (Show Details)Jan 26 2019, 11:32 AM

Aklapper renamed this task from purge attempts fails with 503 error to Purge attempts for specific page on Commons fails with 503 error.Jan 26 2019, 12:20 PM

Aklapper added projects: MediaWiki-File-management, SRE-swift-storage.

Restricted Application added projects: Commons, Multimedia. · View Herald TranscriptJan 26 2019, 12:20 PM

Well, I think I have found some correlations.

The 503 error is likely accidental here; it appered once or twice, I cannot reproduce it.
The problem concerns many (maybe all?) djvu files with a lot of thumbnails (likely much more than 1000).

Some eamples:

None of them can be purged, and tha latter one was purgable before I generated over 2000 thumbnails for it.

Moreover, I renamed the file:
https://commons.wikimedia.org/wiki/File:Jan_Syga%C5%84ski_-_Historya_Nowego_S%C4%85cza.djvu
to
https://commons.wikimedia.org/wiki/File:PL_Jan_Syga%C5%84ski_-_Historya_Nowego_S%C4%85cza.djvu
and the latter purges without any problem (however the file appeared on wiki few hours after the rename) while the newly uploaded copy under the old name still cannot be purged.

The outdated thumbnails of the original file were available even when the file did not exist.

Ankry renamed this task from Purge attempts for specific page on Commons fails with 503 error to Purge attempts for pages of files with large number of thumbnails fails on Commons.Jan 26 2019, 3:46 PM

Ankry updated the task description. (Show Details)

So that's either SwiftFileBackendFileList or something in FileRepo::quickPurgeBatch timing out. Probably needs some live debugging.

Matlin subscribed.Jan 27 2019, 10:59 AM

Ankry mentioned this in T214843: Undeletion of specific file in Wikimedia Commons fails.Jan 28 2019, 2:18 PM

Ankry mentioned this in T215558: Proofread Page extension on Wikisource is displaying wrong pages; purge on Commons file fails.Jul 4 2019, 8:16 PM

Wargo added a subtask: T186153: outdated DjVu file page thumbnail in cache.Mar 19 2024, 1:33 PM