I'd like to show and discuss typical use cases of gdb for a production MySQL DBA. Some of them were already discussed in blog posts like the following:

http://www.percona.com/blog/2012/09/09/obtain-last-executed-statement-from-optimized-core-dump/ http://www.percona.com/blog/2013/11/11/how-to-extract-all-running-queries-including-the-last-executed-statement-from-a-core-file/ http://mysqlbugs.blogspot.com.au/2012/09/how-to-obtain-all-executing-queries.html http://dom.as/2009/02/15/poor-mans-contention-profiling/ http://dom.as/2010/01/02/read-ahead/ http://dom.as/2009/07/30/evil-replication-management/ http://www.percona.com/blog/2010/03/23/too-many-connections-no-problem/ http://dom.as/2009/12/29/when-bad-things-happen/

and some are even well known as a separate tools, like pt-pmp. But quick review, real life use cases demonstration and discussion may help attendees to know the limitations, outcomes and benefits of attaching gdb to a (hopefully) live MySQL server as a last resort of solving some problems or getting additional useful information for further troubleshooting before restarting it.