Last modified: 2011-11-29 03:21:01 UTC

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Bug 7807 - Some squid caches serving stale image and thumbnail versions
Some squid caches serving stale image and thumbnail versions
Status: RESOLVED FIXED
Product: Datasets
Classification: Unclassified
General/Unknown (Other open bugs)
unspecified
All All
: Normal normal with 1 vote (vote)
: ---
Assigned To: Nobody - You can work on this!
http://en.wikipedia.org/wiki/Wikipedi...
:
Depends on:
Blocks:
  Show dependency treegraph
 
Reported: 2006-11-04 23:34 UTC by Ilmari Karonen
Modified: 2011-11-29 03:21 UTC (History)
2 users (show)

See Also:
Web browser: ---
Mobile Platform: ---
Assignee Huggle Beta Tester: ---


Attachments
Patch to includes/SquidUpdate.php (not committing this myself, since I can't test it) (649 bytes, patch)
2008-06-14 22:29 UTC, Ilmari Karonen
Details

Description Ilmari Karonen 2006-11-04 23:34:27 UTC
Some but not all of the squid caches seem to be serving stale versions of both
thumbnails and original images.  Purging or reuploading does not seem to help. 
I have personally only encountered this problem with SVG images so far, but I
expect it probably affects all images.

See for example [[Wikipedia talk:WikiProject Mathematics/Graphics#Blank thumb in
svg?]]: the image
http://upload.wikimedia.org/wikipedia/en/thumb/0/05/Paley13.svg/200px-Paley13.svg.png
shows up for me as an old, blank version, while the 201-pixel thumb shows up
just fine.  The HTTP response headers I get for the affected thumbnail are:

Connection: close
Date: Sat, 04 Nov 2006 20:12:44 GMT
Via: 1.0 sq6.pmtpa.wmnet:80 (squid/2.6.STABLE3), 1.0 sq12.wikimedia.org:80
(squid/2.6.STABLE4), 1.0 ragweed.knams.wikimedia.org:80 (squid/2.6.STABLE5), 1.0
vandale.knams.wikimedia.org:80 (squid/2.6.STABLE3)
Age: 2618
Server: lighttpd/1.4.13
Content-Length: 271
Content-Type: image/png
Client-Date: Sat, 04 Nov 2006 20:55:41 GMT
Client-Peer: 145.97.39.156:80
Client-Response-Num: 1
X-Cache: HIT from sq6.pmtpa.wmnet
X-Cache: MISS from sq12.wikimedia.org
X-Cache: HIT from ragweed.knams.wikimedia.org
X-Cache: MISS from vandale.knams.wikimedia.org
X-Cache-Lookup: HIT from sq6.pmtpa.wmnet:80
X-Cache-Lookup: MISS from sq12.wikimedia.org:80
X-Cache-Lookup: HIT from ragweed.knams.wikimedia.org:80
X-Cache-Lookup: MISS from vandale.knams.wikimedia.org:80
X-Powered-By: PHP/5.1.4

whereas the headers for the seemingly unaffected 201-pixel thumbnail are:

Connection: close
Date: Sat, 04 Nov 2006 19:59:07 GMT
Via: 1.0 sq7.pmtpa.wmnet:80 (squid/2.6.STABLE3), 1.0 sq12.wikimedia.org:80
(squid/2.6.STABLE4), 1.0 ragweed.knams.wikimedia.org:80 (squid/2.6.STABLE5)
Age: 3452
Server: lighttpd/1.4.13
Content-Type: image/png
Client-Date: Sat, 04 Nov 2006 20:55:57 GMT
Client-Peer: 145.97.39.156:80
Client-Response-Num: 1
X-Cache: HIT from sq7.pmtpa.wmnet
X-Cache: MISS from sq12.wikimedia.org
X-Cache: HIT from ragweed.knams.wikimedia.org
X-Cache-Lookup: HIT from sq7.pmtpa.wmnet:80
X-Cache-Lookup: MISS from sq12.wikimedia.org:80
X-Cache-Lookup: HIT from ragweed.knams.wikimedia.org:80
X-Powered-By: PHP/5.1.4

Of course, it's possible the both thumbs are affected, but the latter one just
happens to have been generated after the original image was fixed, and thus does
not appear blank.
Comment 1 Ilmari Karonen 2006-11-12 21:36:25 UTC
http://upload.wikimedia.org/wikipedia/en/thumb/8/8a/RobertJohson.jpg/250px-RobertJohson.jpg
is also affected, serving a thumbnail of a version that's been deleted since 15
October!  See original complaint at
http://en.wikipedia.org/wiki/Wikipedia:Village_pump_%28technical%29#Distorted_image

I've tried purging, reverting, deleting, undeleting and various combinations
thereof without results.  Manually issuing HTTP "Cache-Control: no-cache"
request headers doesn't help either.  For what it's worth, the response headers
I'm getting include:

GET
http://upload.wikimedia.org/wikipedia/en/thumb/8/8a/RobertJohson.jpg/250px-RobertJohson.jpg
--> 200 OK
Connection: close
Date: Sun, 12 Nov 2006 20:53:06 GMT
Via: 1.0 sq14.wikimedia.org:80 (squid/2.6.STABLE5), 1.0 sq13.wikimedia.org:80
(squid/2.6.STABLE5), 1.0 mayflower.knams.wikimedia.org:80 (squid/2.6.STABLE3),
1.0 ragweed.knams.wikimedia.org:80 (squid/2.6.STABLE5)
Accept-Ranges: bytes
Age: 909
ETag: "-299518909"
Server: lighttpd/1.4.13
Content-Length: 31440
Content-Type: image/jpeg
Last-Modified: Wed, 28 Jun 2006 23:25:07 GMT
Client-Date: Sun, 12 Nov 2006 21:08:16 GMT
Client-Peer: 145.97.39.156:80
Client-Response-Num: 1
X-Cache: HIT from sq14.wikimedia.org
X-Cache: MISS from sq13.wikimedia.org
X-Cache: HIT from mayflower.knams.wikimedia.org
X-Cache: MISS from ragweed.knams.wikimedia.org
X-Cache-Lookup: HIT from sq14.wikimedia.org:80
X-Cache-Lookup: MISS from sq13.wikimedia.org:80
X-Cache-Lookup: HIT from mayflower.knams.wikimedia.org:80
X-Cache-Lookup: MISS from ragweed.knams.wikimedia.org:80

with some variants including

GET
http://upload.wikimedia.org/wikipedia/en/thumb/8/8a/RobertJohson.jpg/250px-RobertJohson.jpg
--> 200 OK
Connection: close
Date: Sun, 12 Nov 2006 20:53:06 GMT
Via: 1.0 sq14.wikimedia.org:80 (squid/2.6.STABLE5), 1.0 sq13.wikimedia.org:80
(squid/2.6.STABLE5), 1.0 mayflower.knams.wikimedia.org:80 (squid/2.6.STABLE3),
1.0 vandale.knams.wikimedia.org:80 (squid/2.6.STABLE3)
Accept-Ranges: bytes
Age: 906
ETag: "-299518909"
Server: lighttpd/1.4.13
Content-Length: 31440
Content-Type: image/jpeg
Last-Modified: Wed, 28 Jun 2006 23:25:07 GMT
Client-Date: Sun, 12 Nov 2006 21:08:12 GMT
Client-Peer: 145.97.39.156:80
Client-Response-Num: 1
X-Cache: HIT from sq14.wikimedia.org
X-Cache: MISS from sq13.wikimedia.org
X-Cache: HIT from mayflower.knams.wikimedia.org
X-Cache: MISS from vandale.knams.wikimedia.org
X-Cache-Lookup: HIT from sq14.wikimedia.org:80
X-Cache-Lookup: MISS from sq13.wikimedia.org:80
X-Cache-Lookup: HIT from mayflower.knams.wikimedia.org:80
X-Cache-Lookup: MISS from vandale.knams.wikimedia.org:80

and

GET
http://upload.wikimedia.org/wikipedia/en/thumb/8/8a/RobertJohson.jpg/250px-RobertJohson.jpg
--> 200 OK
Connection: close
Date: Sun, 12 Nov 2006 20:53:06 GMT
Via: 1.0 sq14.wikimedia.org:80 (squid/2.6.STABLE5), 1.0 sq13.wikimedia.org:80
(squid/2.6.STABLE5), 1.0 mayflower.knams.wikimedia.org:80 (squid/2.6.STABLE3),
1.0 sage.knams.wikimedia.org:80 (squid/2.6.STABLE3)
Accept-Ranges: bytes
Age: 895
ETag: "-299518909"
Server: lighttpd/1.4.13
Content-Length: 31440
Content-Type: image/jpeg
Last-Modified: Wed, 28 Jun 2006 23:25:07 GMT
Client-Date: Sun, 12 Nov 2006 21:08:02 GMT
Client-Peer: 145.97.39.156:80
Client-Response-Num: 1
X-Cache: HIT from sq14.wikimedia.org
X-Cache: MISS from sq13.wikimedia.org
X-Cache: HIT from mayflower.knams.wikimedia.org
X-Cache: MISS from sage.knams.wikimedia.org
X-Cache-Lookup: HIT from sq14.wikimedia.org:80
X-Cache-Lookup: MISS from sq13.wikimedia.org:80
X-Cache-Lookup: HIT from mayflower.knams.wikimedia.org:80
X-Cache-Lookup: MISS from sage.knams.wikimedia.org:80

and

GET
http://upload.wikimedia.org/wikipedia/en/thumb/8/8a/RobertJohson.jpg/250px-RobertJohson.jpg
--> 200 OK
Connection: close
Date: Sun, 12 Nov 2006 20:53:06 GMT
Via: 1.0 sq14.wikimedia.org:80 (squid/2.6.STABLE5), 1.0 sq13.wikimedia.org:80
(squid/2.6.STABLE5), 1.0 mayflower.knams.wikimedia.org:80 (squid/2.6.STABLE3)
Accept-Ranges: bytes
Age: 518
ETag: "-299518909"
Server: lighttpd/1.4.13
Content-Length: 31440
Content-Type: image/jpeg
Last-Modified: Wed, 28 Jun 2006 23:25:07 GMT
Client-Date: Sun, 12 Nov 2006 21:01:44 GMT
Client-Peer: 145.97.39.156:80
Client-Response-Num: 1
X-Cache: HIT from sq14.wikimedia.org
X-Cache: MISS from sq13.wikimedia.org
X-Cache: HIT from mayflower.knams.wikimedia.org
X-Cache-Lookup: HIT from sq14.wikimedia.org:80
X-Cache-Lookup: MISS from sq13.wikimedia.org:80
X-Cache-Lookup: HIT from mayflower.knams.wikimedia.org:80
Comment 2 Rodney Rehm 2007-10-08 14:44:22 UTC
Hey there,

i'm not sure if I should've opened a new report, but I think your observations only prove mine:

I was having a (deeper) look at your includes/SquidUpdate.php to get a clue of how to deal with my own squids.

Here's the broken code: http://phpfi.com/267445 (relevant comments prefixed with "globe:")
Here's a simple test proving the bug: http://phpfi.com/267447

The programmer's supplying an index, where he definately shouldn't have.
$sockets[$so+1] should be $sockets[] and everything is fine :)

I've never used mediaWiki, so i've never actually run the code. But from reading (and the little test) i'd say it's not a feature ;)

It seems that the bug is in both, the branch and trunk:
http://svn.wikimedia.org/viewvc/mediawiki/branches/REL1_11/phase3/includes/SquidUpdate.php?view=markup
http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/includes/SquidUpdate.php?view=markup


keep it up, cheers,
Rod
Comment 3 Ilmari Karonen 2008-06-14 22:29:49 UTC
Created attachment 4977 [details]
Patch to includes/SquidUpdate.php (not committing this myself, since I can't test it)

Wow, that indeed looks broken.  And it's been that way since r13845!  Here's a simple patch that should fix it; the only reason I'm not committing it myself is that I can't test it, not having any squids to purge.
Comment 4 Brion Vibber 2008-06-16 20:20:15 UTC
Change sounds reasonable -- applied on r36351.

This code path hasn't been exercised on our servers in a long long time (we'd switched to HTCP and multicast stuff long ago).

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