Leverage lock-free SHOW SLAVE STATUS NONBLOCKING as well

[Roman Vynar]

Previously, we implemented a lock-free SHOW SLAVE STATUS NOLOCK.
However, it was recently changed to SHOW SLAVE STATUS NONBLOCKING in Percona Server 5.6 to be consistent with MySQL 5.7 syntax.
http://www.percona.com/doc/percona-server/5.6/reliability/show_slave_status_nolock.html

[Roman Vynar (roman-vynar)]

* docs/cacti/mysql-templates.rst
* cacti/scripts/ss_get_mysql_stats.php
* nagios/bin/pmp-check-mysql-replication-delay
* nagios/bin/pmp-check-mysql-replication-running

[monty solomon (monty+launchpad)]

FYI, the NONBLOCKING option was removed in 5.7.6.

Excerpt from

http://dev.mysql.com/doc/refman/5.7/en/show-slave-status.html
This option was removed in MySQL 5.7.6 due to locking changes that render it unnecessary.

[Roman Vynar (roman-vynar)]

Thanks monty!

[monty solomon (monty+launchpad)]

SHOW SLAVE STATUS NOLOCK/NONBLOCKING is no longer needed as of 5.6.23.

The hanging SHOW SLAVE STATUS issue (bug #1386363) was fixed in 5.6.23.

[Roman Vynar (roman-vynar)]

Awesome!

[Roman Vynar (roman-vynar)]

Per discussion with Laurynas about bug #1386363, that bug avoids a different lock than NONBLOCKING.
So I think I will try to iterate over those commands in order until first success:
- show slave status nonblocking
- show slave status nolock
- show slave status

Shouldn't be any harm and it will account all possible setups/versions.