独角兽说：“打开文件读取错误：权限被拒绝”

Question

I'm running a rails 3 application running on unicorn, every now and then I get this message:

Error opening file for reading: Permission denied

and that's it. I don't know what file or what component is trying to opening it. It doesn't happen on each request or any other external event that I can figure out.

Any ideas what might be going on or how to try to figure it out?

I tried searching for "Error opening file for reading" on all the gems I'm using, with no luck.

Answer 1

I started seeing this from time to time in Passenger logs after upgrading to ubuntu 12.04. I narrowed it down to some image processing and it apparently comes from Ubuntu's patches to libjpeg-turbo library.

It is trying to access /proc/self/auxv to determine some system capabilities, but that proc file seems not to be always readable, presumably after a process setuid()s to another user when dropping privileges.

As far as I can tell, the library works even if that fails, so it shouldn't cause any major issues.

There seems to be a related bug report at https://bugs.launchpad.net/ubuntu/+source/virtualbox/+bug/1014487

Answer 2

I started running following command in Ubuntu 12.04

sudo apt-get update

after running above command, the "Error opening file for reading: Permission denied" was solved.