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[Launchpad Bug Tracker <326768@xxxxxxxxxxxxxxxxxx>]

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--Impact--
I'm running mythtv on jaunty with mysql-server-5.0 version 5.1.30really5.0.75-0ubuntu5.  During boot mysql starts, then mythtv starts, then mysql restarts and mythtv gets confused.

This is caused by some portions of a debian patch that is applied on top
of MySQL.  It has not been accepted yet at upstream MySQL.  The MySQL
server is receiving a SIGHUP which the behavior is changed because of
the debian patch.

Here are some relevant syslog sections:

Feb  8 12:35:07 willvo mysqld_safe[3668]: started
Feb  8 12:35:08 willvo mysqld[3671]: 090208 12:35:08  InnoDB: Started; log sequence number 0 43655
Feb  8 12:35:08 willvo mysqld[3671]: 090208 12:35:08 [Note] /usr/sbin/mysqld: ready for connections.
Feb  8 12:35:08 willvo mysqld[3671]: Version: '5.0.75-0ubuntu5'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  (Ubuntu)
Feb  8 12:35:08 willvo /etc/mysql/debian-start[3710]: Upgrading MySQL tables if necessary.
Feb  8 12:35:08 willvo /etc/mysql/debian-start[3713]: Looking for 'mysql' as: /usr/bin/mysql
Feb  8 12:35:08 willvo /etc/mysql/debian-start[3713]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck
Feb  8 12:35:08 willvo /etc/mysql/debian-start[3713]: This installation of MySQL is already upgraded to 5.0.75, use --force if you still need to run mysql_upgrade
Feb  8 12:35:08 willvo /etc/mysql/debian-start[3720]: Checking for insecure root accounts.
Feb  8 12:35:08 willvo /etc/mysql/debian-start[3724]: Triggering myisam-recover for all MyISAM tables

Feb  8 12:35:13 willvo mythtv-backend[4560]: Started mythtv-backend

Feb  8 12:35:16 willvo mysqld_safe[5212]: Number of processes running now: 1
Feb  8 12:35:16 willvo mysqld_safe[5223]: mysqld process hanging, pid 3670 - killed
Feb  8 12:35:16 willvo mysqld_safe[5227]: restarted
Feb  8 12:35:16 willvo mysqld[5231]: 090208 12:35:16  InnoDB: Started; log sequence number 0 43655
Feb  8 12:35:17 willvo mysqld[5231]: 090208 12:35:17 [Note] /usr/sbin/mysqld: ready for connections.
Feb  8 12:35:17 willvo mysqld[5231]: Version: '5.0.75-0ubuntu5'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  (Ubuntu)

Note that mysqld_safe is finds one mysqld process still running after it
is supposed to have crashed.  mysqld_safe then kills that process and
starts another.  This only seems to happen once during boot - it doesn't
keep restarting mysqld in normal use.

--Addressing--
This has *not* yet been addressed in the karmic branch, but it has been verified that a PPA resolve the problem.  MySQL hasn't changed yet in karmic, so this can easily be brought to karmic if viewed to properly solve the problem.

--Test Case--
To reproduce this, you can boot up off of a fresh install of Mythbuntu 9.04 (which includes MySQL and mythtv-backend preinstalled).  Check /var/log/syslog and you will see errors regarding mysql getting restarted because of a hanging process.  Depending on the speed of your system, this may or may not cause problems with mythtv-backend because of the race condition inherent in this problem.

--Regression Potential--
This type of patch has implications if users were dependent on the behavior of this debian/ubuntu specific patch to issue a mysql refresh via a SIGHUP.

** Affects: mythbuntu
     Importance: Critical
         Status: Triaged

** Affects: mysql-dfsg-5.0 (Ubuntu)
     Importance: Undecided
     Assignee: Canonical Server Team (canonical-server)
         Status: Confirmed

** Affects: mysql-dfsg-5.0 (Ubuntu Jaunty)
     Importance: Undecided
         Status: Confirmed

** Affects: mysql-dfsg-5.0 (Ubuntu Karmic)
     Importance: Undecided
     Assignee: Canonical Server Team (canonical-server)
         Status: Confirmed

-- 
mysqld_safe thinks mysqld has crashed when it hasn't
https://bugs.edge.launchpad.net/bugs/326768
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