How to run multiple PHP sites using same APC cache?

Question

Ok, the situation is I have multiple php sites all running on the same server using the same CMS. There is no change in the core code or modules for the CMS between sites so would like to have all sites use the same code repository to make it easier to keep all the sites running the same version.

This part is easy enough to do using symbolic links, but ideally I would like the files only to be cached by APC once so the core code is already cached for all the sites.

The setup is PHP 5.2, APC, apache.

Without knowing much about APC i'm guessing the pathing is done from the symbolic link so they appear as different files between the sites. With the CMS at my last job it used pointer files to include the main code, but would like to avoid this as it is messy and makes it harder to maintain. The other question is whether different sites can use the same cache, in looking up this problem I have noticed issues with fastcgi not being able to share between processes.

Any help would be greatly appreciated.

Answer 1

I've considered that by using pointer files, a file in the main website to include each relevant file, but the cms itself is around 100 files, plus more for any modules used. For the cms itself to work properly, the files need to be in some way physically in the subdirectory of the main site. I'm thinking it isn't really possible, shame, as it would have been nice if it was. Currently running on a VPS so memory is limited.