APC cache cleaned every couple of seconds

[spok]

Hi,

I use APC to cache php scripts to increase performance.

Now I tried to
- increase cache size
- enable APC as cache handler in Joomla - conservative caching
- cache time 60 minutes.

All looks good, page is much faster know, but cache is cleaned every couple of seconds although I set:

- apc.gc_ttl 3600
- apc.ttl 3600
- apc.user_ttl 7200

In this way apc.php only shows some 100 to 1000 hits.

This behaviour didn´t show up as long as I used APC only for scripts - caching Joomla to file (nothing changed within APC). Doing this apc.php showed i. e. 200.000 hits when has built up.

Any idea?

[itoctopus]

Have you enabled Joomla's "System - Cache" plugin?

[spok]

Of course ...

[spok]

I just set cache back to "file" and obviously the behaviour is the same ..., i. e. cache is cleaned every few seconds.

Two days ago I used APC to cache php scripts - as already mentioned - and had a look at apc.php when the cache ist already running for hours. Cache size was 128M, filled to about 60%, and hits to misses relationship was about 99:1 (about 200.000 hits).

Then I used APC to cache page also by setting Joomla cache handler to "Alternative PHP Cache". I increased cache size to 1536M, anticipating that I will need this size, because not only scripts, but also pages will be cached.

I expected that cache size would grow until all scripts and pages are cached - limited of course by the ttl of pages and scripts.

What I found was that the cache is cleaned every few seconds, and now I find the same behaviour when setting Joomla back to "file" cache, so that APC only caches scripts.

Does anybody have an explanation for this?

Which APC or Joomla parameters could be relevant?

I thought that only APC ttl parameters need to be considered as mentioned above already?

- apc.gc_ttl 3600
- apc.ttl 3600
- apc.user_ttl 7200

Any idea?