Apache segfault glibc segfault
Solution 1:
If you are using PHP 5.4.x, then the latest stable version of APC (3.1.9) won't work. You need 3.1.10, which is listed currently as beta. So:
pear install apc-beta
should do it.
Solution 2:
At least php-fpm + APC is a known problematic combination. Might also affect PHP 5.4.x + APC, too, regardless what mode (mod_php, php-fpm, suPHP ...) your PHP is running on. It's APC which is buggy in this case.
Disabling APC should help. Have you tried XCache instead?