Topic on Project:Support desk

I previously reported that I was getting an error 500 on Special:SpecialPages after upgrading to 1.22. After a while I reported that the error appeared to have gone away. However I am still getting occasional errors on this page. Everything else appears to work correctly but I haven't tested every single piece of functionality so I cannot guarantee this - if anyone wants to give it a go (without corrupting content!) you can find my wiki at http://www.festipedia.org. Checking the Apache error log I am getting three different errors:

• Seg fault
• zend_mm_heap corrupted
• Allowed memory size of 134217728 bytes exhausted (tried to allocate <very large number> bytes) in includes/context/RequestContext.php on line 350 (the very large number is typically in the range 8Gb - 20 Gb - I can provide the actual numbers if it would help)

Looking at RequestContext.php it doesn't look like it should be allocating any memory on line 350 so I'm guessing this is some kind of corruption.

Details for my setup are:

MediaWiki 1.22.0 PHP 5.3.6 (apache2handler) MySQL 5.1.56

I have a lot of extensions installed (a subset of those on the English Wikipedia) but I have tried commenting them all out in LocalSettings.php and it doesn't make any difference so I don't think it is related to any of those. Just in case it is relevant, my current LocalSettings.php was copied from my 1.21 setup. All I have done to it is remove some extensions that are now part of core.

Any thoughts?

Correction - the URL for my wiki is http://www.festipedia.org.uk. Sorry.

Allocating 8-20 GB (!) I have no idea what could cause that, but maybe something wrong with your version of PHP (shot in the dark)

Just to clarify, the error happens only when viewing Special:SpecialPages? Or does it appear at random page requests? Or always on the same page?

I have only seen it when viewing Special:SpecialPages. I cannot rule out the possibility that it also happens on other pages but I haven't seen it. When I first upgraded to 1.22.0 it would fail on Special:SpecialPages every time. After a few hours it started working properly, then it failed consistently for several hours, then it started working again. Now it works more often than it fails and when it does fail it usually starts working again on the second or third attempt to view Special:SpecialPages.

I'm not ruling anything out but I would be surprised if it is my version of PHP. It is a supported version and hasn't given a problem before. At one point I thought it my be due to APC but disabling that had no effect.

I note that some other people have reported problems immediately after upgrading but the issues have gone away (or the poster has stopped responding!) without any fix being applied. I don't know if the problem I'm seeing is a symptom of the same issue or something different. If it is something I've done I'd like to fix it! If it is a problem in 1.22.0 I'd like to help debug it, so happy to provide any information that would help to get to the bottom of this.

Googling around I could find some possible causes:

• Bad session manager
• I've seen various errors related to this when using some opcode cache, e-accelerator, apc, etc. Probably not the opcode fault
• Not enough memory (that would explain when you get "Allowed memory size of NNNNN bytes exhausted")
• Some say increasing PHP's output_buffering sometimes solves the problem

But nothing conclusive :(

Thanks for the ideas. Unfortunately they haven't helped.

Checking the log shows that this does occasionally happen on other pages but it seems to reproduce most reliably on Special:SpecialPages.

Checking the figures for the large memory allocations, the most common one is 0x400000000 which looks suspicious. The second most common figure is 0xd04845e7 which looks a bit more random.

I have exactly the same problem too. The memory limit is set to memory_limit = 128M and output_buffering = 4096. I also tried the update script and update special pages script.

Turns out my issue is being caused by the multiupload extension, simply commenting it out in localsettings.php fixes the issue. I am assuming that it must reference the old Vector extension somewhere.