ReleaseUpgrade issues

[Michael Vogt]

Hi,

I would like to raise awareness of possible issues for release
upgrades when new libraries/themes are packaged. This can be themes
that change the file layout in new versions or libraries that
dynamically load "plugins" (or potentially other things, but these are
the most common ones). In general libraries are not a problem because
even when they change/get removed the application that uses it has a
open handle and that makes linux keep it available until the last
reference is removed. But for everything that is loaded dynamically
(pango, pixbufloaders, etc) this can become a problem. 

We had e.g. gtk+ move its (dynamically loaded) pixbuf loaders from
/usr/lib/gtk-2.0/2.4.0/loaders to
/usr/lib/gtk-2.0/2.10.0/loaders. This resulted in problems for
applications that were started before the upgrade (e.g. the
ReleaseUpgrader itself). Here, it was "just" a matter of missing
icons. 

For the crux theme that changed it on disk-layout matters were worse,
when crux was used, applications crashed when a new crux was installed
because it couldn't load its theme bits anymore.

So if you come across a situation like this it would be good to test
if it affects runing applications and causes bad behaviour and post
it to the list. I seems to me like upstreams are not generally aware
of this too.

Cheers,
 Michael