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[homepage.git] / blog / archive / 2010 / 07 / 07.rss

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@@ -1056,5 +1056,62 @@ http://wiki.debian.org/DebianEdu/HowTo/ReportBugsInBugzilla</p>
 </description>
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+       <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>
+&lt;p&gt;I discovered this while doing
+&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Automatic_upgrade_testing_from_Lenny_to_Squeeze.html&quot;&gt;automated
+testing of upgrades from Debian Lenny to Squeeze&lt;/a&gt;.  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.&lt;/p&gt;
+
+&lt;p&gt;An example is from todays
+&lt;a href=&quot;http://people.skolelinux.org/~pere/debian-upgrade-testing//test-20100727-lenny-squeeze-kde-aptitude.txt&quot;&gt;upgrade
+of KDE using aptitude&lt;/a&gt;.  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.&lt;/p&gt;
+
+&lt;p&gt;In this log, the problem manifest itself with this error:&lt;/p&gt;
+
+&lt;blockquote&gt;&lt;pre&gt;
+dpkg: dependency problems prevent configuration of perl-modules:
+ perl-modules depends on perl (&gt;= 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
+&lt;/pre&gt;&lt;/blockquote&gt;
+
+&lt;p&gt;The perl/perl-modules circular dependency is already
+&lt;a href=&quot;http://bugs.debian.org/527917&quot;&gt;reported as a bug&lt;/a&gt;, 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.&lt;/p&gt;
+
+&lt;p&gt;Thanks to
+&lt;a href=&quot;http://lists.debian.org/debian-devel/2010/06/msg00116.html&quot;&gt;the
+tireless effort by Bill Allombert&lt;/a&gt;, the number of circular
+dependencies
+&lt;a href=&quot;http://debian.semistable.com/debgraph.out.html&quot;&gt;left in Debian
+is dropping&lt;/a&gt;, and perhaps it will reach zero one day. :)&lt;/p&gt;
+
+&lt;p&gt;Todays testing also exposed a bug in
+&lt;a href=&quot;http://bugs.debian.org/590605&quot;&gt;update-notifier&lt;/a&gt; and
+&lt;a href=&quot;http://bugs.debian.org/590604&quot;&gt;different behaviour&lt;/a&gt; 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.&lt;/p&gt;
+</description>
+       </item>
+       
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