Debugging with innodb_lock_monitor

[DRivard]

Hi,

I would like to know if there is a way to get the innodb_lock_monitor enabled on a galera cluster.

I followed the instructions about creating the required table.

CREATE TABLE innodb_lock_monitor (a INT) ENGINE=INNODB;

on the MySQL database, and when I run the query 

SHOW ENGINE INNODB STATUS\G

The section about the deadlock doesn't appears.

The thing is that just before running the innodb status I performed a query that was returning a deadlock so it should contain some information but it doesn't.

I also tried to create the innodb_lock_monitor on the database I was getting the deadlocks but I didn't get much informations. 

do you know a way to get this activated?

Best,

Dominick

[seppo....@codership.com]

There are two kinds of deadlocks:

* natural InnoDB deadlocks, that would happen with single MySQL server
* cluster conflicts, which are caused by simultaneous writes to same
data elements in separate cluster nodes.

Only natural InnoDB deadlocks are logged in INNODB STATUS output.

Currently there is not much diagnostics from cluster conflicts. Only
way to monitor them in more detail is by enabling wsrep_debug. However
that will cause other superfluous log messages. We are working on ways
to improve cluster conflict diagnostics. First step in this is to add
new variable: wsrep_log_conflicts, which will enable cluster conflict
reporting in mysql error log. We will probably get this feature for
the next 2.2 release.

wsrep_retry_autocommit can be tried to help with deadlocks, if
application cannot deal with deadlock errors.

-seppo

> --

[Laurent MINOST]

Hi Seppo,

Do you have an ETA for the next 2.2 release and a list of changes please ?

Regards,

Laurent