I read the post on stackoverflow, some valuable info there.
-- Compiling the APC module with --disable-apc-mmap (Disable mmap support and use IPC shm instead) should fix the issue.
-- i use SuPHP, not FastCGI
-- my hosting said he is unable to enable fastcgi on litespeed. what if i still use suphp?
when you use SuPHP under apache, and converting apache to litespeed, php will run in suExec mode. in this mode, only eAccelerator works well, APC or XCache won't work well. and in memory variable won't be shared at all between lsphp processes. in php suExec mode, lsphp process start/stop frequently. once a process stops, all in memory variables associated with the process will vanish as well. so use memcache or even disk file is the right way to keep variable value between lsphp process.