- <item>
- <title>Circular package dependencies harms apt recovery</title>
- <link>http://people.skolelinux.org/pere/blog/Circular_package_dependencies_harms_apt_recovery.html</link>
- <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Circular_package_dependencies_harms_apt_recovery.html</guid>
- <pubDate>Tue, 27 Jul 2010 23:50:00 +0200</pubDate>
- <description>
-<p>I discovered this while doing
-<a href="http://people.skolelinux.org/pere/blog/Automatic_upgrade_testing_from_Lenny_to_Squeeze.html">automated
-testing of upgrades from Debian Lenny to Squeeze</a>. A few packages
-in Debian still got circular dependencies, and it is often claimed
-that apt and aptitude should be able to handle this just fine, but
-some times these dependency loops causes apt to fail.</p>
-
-<p>An example is from todays
-<a href="http://people.skolelinux.org/~pere/debian-upgrade-testing//test-20100727-lenny-squeeze-kde-aptitude.txt">upgrade
-of KDE using aptitude</a>. In it, a bug in kdebase-workspace-data
-causes perl-modules to fail to upgrade. The cause is simple. If a
-package fail to unpack, then only part of packages with the circular
-dependency might end up being unpacked when unpacking aborts, and the
-ones already unpacked will fail to configure in the recovery phase
-because its dependencies are unavailable.</p>
-
-<p>In this log, the problem manifest itself with this error:</p>
-
-<blockquote><pre>
-dpkg: dependency problems prevent configuration of perl-modules:
- perl-modules depends on perl (>= 5.10.1-1); however:
- Version of perl on system is 5.10.0-19lenny2.
-dpkg: error processing perl-modules (--configure):
- dependency problems - leaving unconfigured
-</pre></blockquote>
-
-<p>The perl/perl-modules circular dependency is already
-<a href="http://bugs.debian.org/527917">reported as a bug</a>, and will
-hopefully be solved as soon as possible, but it is not the only one,
-and each one of these loops in the dependency tree can cause similar
-failures. Of course, they only occur when there are bugs in other
-packages causing the unpacking to fail, but it is rather nasty when
-the failure of one package causes the problem to become worse because
-of dependency loops.</p>
-
-<p>Thanks to
-<a href="http://lists.debian.org/debian-devel/2010/06/msg00116.html">the
-tireless effort by Bill Allombert</a>, the number of circular
-dependencies
-<a href="http://debian.semistable.com/debgraph.out.html">left in Debian
-is dropping</a>, and perhaps it will reach zero one day. :)</p>
-
-<p>Todays testing also exposed a bug in
-<a href="http://bugs.debian.org/590605">update-notifier</a> and
-<a href="http://bugs.debian.org/590604">different behaviour</a> between
-apt-get and aptitude, the latter possibly caused by some circular
-dependency. Reported both to BTS to try to get someone to look at
-it.</p>
-</description>
- </item>
-