Magento APC optimisation

Written by Peter Davies on 10 April 2010.

Extremely useful Magento optimisation links:

APC Cache - having used this on many server configuration together with the Zend Framework, I can see that implementing this Magento should have big advantages. http://www.magentocommerce.com/boards/viewthread/8937/

In the app/etc/config.xml you need after the <global> section:

        <cache>
                <backend>apc</backend>
                <prefix>sitename_</prefix>
        </cache>

On Debian don't use the object-based "user cache" as suggested here. Simply enable the "file cache" using the values below. You will need to experiment with the size of the segment as Magento can use a lot of the shared memory in only a few minutes. Memcache seems much more stable for object caching.

APC Configuration

Edit the file /etc/php5/conf.d/apc.ini

extension=apc.so

apc.enabled=1
apc.shm_segments=1
apc.shm_size=256
apc.num_files_hint=10000
apc.user_entries_hint=10000
apc.max_file_size=5M

apc.ttl=0
apc.user_ttl=0
apc.gc_ttl=60
apc.stat=1
apc.optimization = 0
apc.cache_by_default=1
apc.enable_cli=1
apc.slam_defense=0
apc.write_lock=1

You will need to restart Apache for this to take effect using apache2ctl graceful. Once operational you can use the apc.php available in the modules src folder to examine what's happening; you should see something like:

Other optimisation around APC

MySQL Specific - in particular, looking at innodb pool size, I've seen dramatic improvements:
http://www.magentocommerce.com/boards/viewthread/4168/

Apache - simply increasing available Apache process solves most issues; assuming there is available memory.