APC and Omeka

According to my server admin, when moving the Omeka site from development to staging, he ran into a problem with our PHP settings.

With APC turned on for all sites then Omeka 2.1.4 was not returning any response and the Apache httpd error log was saying:
[Mon May 12 09:11:32 2014] [notice] child pid 25064 exit signal Segmentation fault (11)
(that is, the httpd process that was handling the request was dying with fatal hw memory protection error)

I added this to the virtual host configuration and the problem went away:
php_flag apc.cache_by_default Off

It looks like that could be managed in Omeka 1.x using the PageCaching plugin, but that plugin has not been updated for 2.x. Any advice on how to solve this problem without turning off the opcode cache?

Omeka: 2.1.4
APC: 3.1.13
PHP: 5.4.24
Apache: 2.2.3 (CentOS)

I'm not sure what your specific problem is here.

Omeka should work fine with opcode caching; I use APC or the PHP 5.5 built-in opcode cache pretty much everywhere without issue.

Maybe your server's settings for APC are to blame?

Knowing nothing about APC, I couldn't say, but I do have access to most of the configuration info if there's something there that would be helpful.

Could it be as simple as PHP 5.5 working better here than 5.4?

It's certainly possible, just because it's a different opcode cache and you don't need an extension for it in 5.5.

It's definitely possible this is just an APC bug. 3.1.13 is a "beta" version from 2012 but is still the latest available. If PHP 5.5 is an option for you I think it's worth checking out.


The plugin has been removed from the site since July 2011, even if the instruction page is still there (http://omeka.org/codex/Plugins/PageCaching).

So I found the plugin on archive.org and made an upgrade for Omeka 2 (see https://github.com/Daniel-KM/PageCaching). I don't check the APC cache, but it works on other ones.


Daniel Berthereau
Infodoc & Knowledge management

Thanks, Daniel. I'll pass it along to our IT department and see what they think.