Issues with PHP 5.3 and sessions folder.

Question

I recently upgraded to PHP 5.3 and since then I get (sporadic) error messages which indicate Apache (or may be the cleaner of the session files) has no permissions to the folder where the sessions are stored.
This happens randomly and can't be reproduced with exact steps, which led me to guess it is the session cleaner.
Any one has any experience with such errors?

The error message (which is fired on the session_start() line) is:

ps_files_cleanup_dir: opendir(/var/lib/php5) failed: Permission denied.

ls -ltr on the session directory gives:

drwx-wx-wt  2 root          root          4096 2010-05-25 12:39 php5

Inside this directory I do see session files owned by www-data which is my Apache, and the app does work fine. Which makes me wonder, under which user does the session GC runs?

Answer 1

The solution I currently use (which I am not sure is the correct one) is to give ownership on the session folder to the Apache user (www-data in my case).

Answer 2

The fix: In your php.ini set session.gc_probability to 0

The cause I believe I found the answer here http://somethingemporium.com/2007/06/obscure-error-with-php5-on-debian-ubuntu-session-phpini-garbage

Essentially, the garbage collection is set up to be done by cron jobs on some systems (i.e. Ubuntu/Debian). Some php ini executables like php-cli also try to do garbage collection and that results in the error you got.