Maniphest T22041

DifferenceEngine.php(1258) : Fatal error - Maximum execution time of 30 seconds exceeded
Closed, ResolvedPublic
Actions

Assigned To

None

Authored By

	• bzimport
	Aug 2 2009, 5:29 PM

Description

Author: rabe

Description:
Every request to our RSS/ATOM fires one apache child to 100% CPU for 30 seconds before PHP's maximum execution time of 30sec kills includes/diff/DifferenceEngine.php

Our error.log shows hundreds of lines (read: hundreds of minutes) every day like
includes/diff/DifferenceEngine.php(1257) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1257) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1264) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1248) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1261) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1258) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1258) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1257) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1261) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1256) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1257) : Fatal error - Maximum execution time of 30 seconds exceeded
includes/diff/DifferenceEngine.php(1257) : Fatal error - Maximum execution time of 30 seconds exceeded

The lines differ from about 1248 to 1264 with a stress on 1257.

You may reproduce this by using wget for example:

$ time wget --no-proxy -O /dev/null "http://wiki.rhein-neckar.de/index.php?title=Spezial:Letzte_Änderungen&feed=rss"
--2009-08-02 19:10:22-- http://wiki.rhein-neckar.de/index.php?title=Spezial:Letzte_%C4nderungen&feed=rss
Resolving wiki.rhein-neckar.de... 62.138.134.203
Connecting to wiki.rhein-neckar.de|62.138.134.203|:80... connected.
HTTP request sent, awaiting response... 500 Internal Server Error
2009-08-02 19:10:52 ERROR 500: Internal Server Error.

real 0m30.127s
user 0m0.000s

sys 0m0.006s

The server's CPU is a "Dual Core AMD Athlon(tm) 64 X2 Dual Core Processor 4200+" which should be more than adequate for a single instance mediawiki.

I expect we had this problem before 1.13, we had it for 1.14.0 and now with 1.15.1.

Please check http://wiki.rhein-neckar.de/index.php/Spezial:Version for installed extensions on our wiki.

If you need more detailed informationen (configuration), please ask!
If you want me to apply patches for testing/profiling/debugging, ... please ask!
If you expect inconsistent data in out database, please send me some checkscripts.

TIA
Raphael Becker

Version: 1.15.x
Severity: major
URL: http://wiki.rhein-neckar.de/index.php?title=Spezial:Letzte_Änderungen&feed=rss

Details

Reference: bz20041

Event Timeline

• bzimport raised the priority of this task from to Medium.Nov 21 2014, 10:48 PM

• bzimport added a project: MediaWiki-Special-pages.

• bzimport set Reference to bz20041.

• bzimport added a subscriber: Unknown Object (MLST).

• bzimport created this task.Aug 2 2009, 5:29 PM

ayg wrote:

Try using the wikidiff2 extension for diffs instead of the PHP-based diff engine.

rabe wrote:

(In reply to comment #1)

Try using the wikidiff2 extension for diffs instead of the PHP-based diff
engine.

Thanks for you quick reply.

According to http://www.mediawiki.org/wiki/Extension:Wikidiff2 this extension is declared "experimental".
We need try this later, I don't have any root access to this server and therefore cannot modify the PHP setup on this server.

I haven't seen this error on many other wikis I care of, so I guess there's nothing wrong with this piece of code in general (many other might have reported this before).

Regards
Raphael Becker

ayg wrote:

wikidiff2 is what Wikipedia uses, IIRC. The built-in diff engine is very CPU-intensive, since it's written in PHP. I'd assume that the RSS feed link is trying to generate a large number of diffs and simply takes too long. I don't know if this is fixable without using a diff engine written in a faster language, like wikidiff2.

I could have sworn there was a dupe bug entry but can't find it.

The slow-diffs-breaking-things problem is old and well known, but we don't have a very good fix for it at the moment for those encountering it other than disabling feed diffs or installing the C++ differ.

What we need here is the ability for the diff class to abort itself cleanly when it's taking too long, allowing for graceful degradation -- skip the slow diffs and just show everything else.

This bug has been marked as a duplicate of bug 7601 ***

RSS/ATOM Feeds / Endless Loop in includes/diff/DifferenceEngine.php(1258) : Fatal error - Maximum execution time of 30 seconds exceededClosed, ResolvedPublicActions