The package debian-goodies, has a great little tool that allows Debian/Ubuntu sysadmin's to check if any software is using code thats been upgraded.

I've hacked the tool to support Gentoo Linux.

Requires the following packages on Gentoo: lsof, lsb-release and portage-utils.

It uses lsof to check if programs in memory is referencing erased data files on disk. When you upgrade a package, the running copy of the software can continue to use old binaries, libraries and other data files, even while they are erased from disk. This gives the tool something to check for to detect what applications in memory needs restarting.

It generates a list of programs that need restarting and to make things easier it uses qfile/qlist to check for init.d scripts, so it can suggest what you need to run.

The program is not intelligent though, it can only create a list you as SysAdmin can use to simplify the process of handling rolling upgrades, not do the restarting automatically.

At the moment the code contains a searchlist, whitelist and blacklist system to trim the list of locations it checks for files that has been updated. If it checked all files, it would detect /dev/zero, /tmp and other files. The default searchlist is configured to detect package upgrades, but other uses is possible by changing these lists. For advanced use you can change it to use a different search list or one of the other methods if it suits your configuration better (There isn't support for mixing the lists, it only support using one type)

To Do:
Implement improved detection of perl/python and other scripting language software, since it's at the moment detected as the scripting language program.

Quit operation for using it in a cron script that only generate output when you have programs running that needs attention.

Implement Command line and configuration file for easier configuration of the way it prunes the list to remove false positives.

Make an ebuild, if upstream continues to show no interest in merging.