https://bugzilla.wikimedia.org/show_bug.cgi?id=67849
Bug ID: 67849 Summary: If-Modified-Since handling is broken Product: MediaWiki Version: unspecified Hardware: All OS: All Status: UNCONFIRMED Severity: major Priority: Unprioritized Component: General/Unknown Assignee: wikibugs-l@lists.wikimedia.org Reporter: bianji...@google.com Web browser: --- Mobile Platform: --- We (crawling team in Google) found that Wikipedia's If-Modified-Since handling is broken, at least when it comes to (Wikipedia-style) redirects/symlinks. As a short-term work-around (in order to serve up-to-date content), we temporarily stopped sending out If-Modified-Since header in the crawl request. Hope you take a look at this issue, and let us know when it is resolved. Below is what we did to reproduce the issue (Actually, we have observed many times that we cannot fetch the latest content of an articles before) 1. Pick a Wikipedia page to vandalize it (apologies for being a vandal; we promise it is for the greater good...), and wait for it is reverted. http://en.wikipedia.org/wiki/SSh (note the capitalization). Its history (http://en.wikipedia.org/w/index.php?title=SSh&action=history) will contains the vandalization at 01:47:42 (GMT) and its rollback at 01:49:06 (GMT) 2. Fetch the url (at 01:47:54 GMT, right after the vandalized revision is submitted) using telnet. It seems the "Last-Modified" is using the last redirect destination's latest revision: 08 Jul 2014 11:49:08 GMT (http://en.wikipedia.org/w/index.php?title=SSL&action=history) $ telnet en.wikipedia.org 80 Trying 2620:0:861:ed1a::1... Connected to text-lb.eqiad.wikimedia.org. Escape character is '^]'. GET /wiki/SSh HTTP/1.1 Host: en.wikipedia.org HTTP/1.1 200 OK Server: Apache X-Content-Type-Options: nosniff Content-language: en X-UA-Compatible: IE=Edge Vary: Accept-Encoding,Cookie Last-Modified: Tue, 08 Jul 2014 11:49:08 GMT Content-Type: text/html; charset=UTF-8 X-Varnish: 4282068392, 1036646122 Via: 1.1 varnish, 1.1 varnish Transfer-Encoding: chunked Date: Thu, 10 Jul 2014 01:47:54 GMT ← This one's accurate; this is when the crawl happened. Age: 0 Connection: keep-alive X-Cache: cp1065 miss (0), cp1053 frontend miss (0) Cache-Control: private, s-maxage=0, max-age=0, must-revalidate Set-Cookie: GeoIP=::::v6; Path=/; Domain=.wikipedia.org …Page for SSL follows… 3. After it's reverted, re-crawl (at 01:50:57 GMT) the article with a If-Modified-Since header, setting to the Last-Modified value in step2 (we are simulating the production crawling works). It's strange that we got a 304 response this time. And the "Last-Modified" value is weird too, neither SSh nor SSH has update around 08 Jul 2014 11:49:08 GMT. $ telnet en.wikipedia.org 80 Trying 2620:0:861:ed1a::1... Connected to text-lb.eqiad.wikimedia.org. Escape character is '^]'. GET /wiki/SSh HTTP/1.1 Host: en.wikipedia.org If-Modified-Since: Tue, 08 Jul 2014 11:49:08 GMT HTTP/1.1 304 Not Modified Server: Apache X-Content-Type-Options: nosniff Content-language: en X-UA-Compatible: IE=Edge Vary: Accept-Encoding,Cookie Last-Modified: Thu, 26 Jun 2014 11:22:21 GMT ← A mysterious timestamp. Content-Type: text/html; charset=UTF-8 X-Varnish: 4282315466 4282211494, 2309645493 Via: 1.1 varnish, 1.1 varnish Date: Thu, 10 Jul 2014 01:50:57 GMT Age: 74 Connection: keep-alive X-Cache: cp1065 hit (1), cp1066 frontend miss (0) Cache-Control: private, s-maxage=0, max-age=0, must-revalidate Set-Cookie: GeoIP=::::v6; Path=/; Domain=.wikipedia.org Connection closed by foreign host. -- You are receiving this mail because: You are the assignee for the bug. You are on the CC list for the bug. _______________________________________________ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l