PHP Apc causing kernel panic

Question

Hey Guys,

We are running APC as an opcode level cache , and have been getting kernel panic's (Shared memory segment related). I thought that anything running in the user space (PHP , APC , Apache) could not cause a kernel panic. I have managed to replicate this issue on different hardware and environments. My questions are

1, Why would apc cause a system level kernel panic (If there is shared segment error shouldnt the application just stop running ? ) 2. Any advice on how to fix investigate this issue

I am running Freebsd

Thanks!

Answer 1

This PECL Bug #13474 has a comment from a user who says they resolved a similar problem by recompiling their APC extension with a different file locking type. They suggest "Spin locking".

They link to an issue that seems to relate to this problem on FreeBSD specifically, so perhaps there's something about using APC in that environment that's broken. The link is unfortunately expired.

What versions of PHP and APC are you using? Are you using the latest version? As of this writing (2010-09-14), the latest versions are PHP 5.3.3 and APC 3.1.4.

Answer 2

We were having similar panic/segfault issues with APC in our SaaS environment across multiple versions and distros (Debian Etch/Lenny, Ubuntu Lucid), and finally resolved them by switching to XCache. It's been well over a year without trouble.