SuperCache-Plus FAQ

Here you can find answers to some of the most frequently asked questions about SuperCache-Plus. If you have a question not answered on this page, you can ask it in the Forums.

  1. Configuration
    1. mod_rewrite is available. Why are there no 'SuperCached' files?
  2. eAccelerator
    1. I have eAccelerator installed and 'working'. Why does it not appear as a …
    2. Why do my changes on the Admin page not show up?
  3. APC
    1. Why do my changes on the Admin page not show up?
  4. Garbage Collection
    1. Why doesn't the site update when I do 'X' ?
      1. Existing Tickets
    2. Why do the SuperCache stats say there are lots of expired files?
    3. What are all the .expired files for?

Configuration

mod_rewrite is available. Why are there no 'SuperCached' files?

TODO

eAccelerator

I have eAccelerator installed and 'working'. Why does it not appear as a storage option?

You're using an eAccelerator that has been built without the 

  --with-eaccelerator-shared-memory

option which is necessary for key storage but has been disabled by default in recent releases.

The functionality that this compile option provides is essential if you want to use the eAccelerator storage option with this plugin.

Why do my changes on the Admin page not show up?

I you have set eaccelerator.check_mtime="0" then you will have problems configuring the plugin.

For technical and performance reasons, SuperCache-Plus saves its configuration to the file wp-content/wpscplus-config.php rather than in the WordPress database and changes to this file will not be read by eAccelerator unless eaccelerator.check_mtime="1"

This is unfortunate, since there is a significant performance improvement to be had with mtime checking disabled.

A possible compromise is to set eaccelerator.filter="!*/wpscplus-config.php" so that the config script is not cached.

APC

Why do my changes on the Admin page not show up?

I you have set apc.stat="0" then you will have problems configuring the plugin.

For technical and performance reasons, SuperCache-Plus saves its configuration to the file wp-content/wpscplus-config.php rather than in the WordPress database and changes to this file will not be read by APC unless apc.stat="1"

This is unfortunate, since there is a significant performance improvement to be had with mtime checking disabled.

A possible compromise is to set apc.filters="wpscplus-config\.php" so that the config script is not cached.

Garbage Collection

Why doesn't the site update when I do 'X' ?

The cache is purged (partially or completely) in the following situations:

  • Publishing a post
  • Changing a post
  • Deleting a post
  • A comment, pingback or trackback is received
  • A comment is moderated
  • A comment is deleted
  • The site's theme is changed
  • The site's permalink structure is changed

If (based on experience please) there's some action that you think is missing from that list, consider creating a ticket.

Existing Tickets

No results

Why do the SuperCache stats say there are lots of expired files?

See: What are all the .expired files for?

What are all the .expired files for?

When a request is received and there is no cache file to serve, WordPress must generate a new page. In high traffic environments many requests could be received in the time it takes to generate a page and each would cause the WordPress engine to load.

Instead, the first request causes the .expired files to be renamed and temporarily served from the SuperCache to all requests until the new cache file is generated. That means that only one request will load the WordPress engine and your server will be much happier.

When you see something like '331 files in cache (278 expired)' in the SuperCache statistics of the Admin page there's no reason to be concerned - the expired files will be deleted eventually. You don't need to do anything.