> * Improve deadlock detection when deleting items from shared buffers
>
>   http://archives.postgresql.org/pgsql-bugs/2008-01/msg00138.php
>   http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php
>   http://archives.postgresql.org/pgsql-committers/2008-01/msg00365.php