MySQL Bugs: #75388: Manual does not really explain how to get information on InnoDB mutexes from P

Bug #75388	Manual does not really explain how to get information on InnoDB mutexes from P_S
Submitted:	1 Jan 2015 20:29	Modified:	2 Jun 2015 14:45
Reporter:	Valeriy Kravchuk	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S3 (Non-critical)
Version:	5.6, 5.7	OS:	Any
Assigned to:	Daniel Price	CPU Architecture:	Any
Tags:	missing_manual, show engine innodb mutex

Description:
Manual (both http://dev.mysql.com/doc/refman/5.7/en/show-engine.html and http://dev.mysql.com/doc/refman/5.6/en/show-engine.html) says:

"SHOW ENGINE INNODB MUTEX output is removed entirely in MySQL 5.7.2. Comparable information can be generated by creating views on Performance Schema tables."

But it does not provide (in one place) any details on how to enable instrumentation for these mutexes (this can be done only at startup at least in 5.6), how to "size" PERFORMANCE_SCHEMA properly for monitoring this kind of mutexes, what exact table(s) to use to get details similar to those in SHOW ENGINE INNODB MUTEX output, how names of mutexes in PERFORMANCE_SCHEMA "correspond" to lines of code/names of mutexes we see in INNODB MUTEX output, nothing of that...

How to repeat:
Try to get the same (or better) information from PERFORMANCE_SCHEMA as one can easily get with SHOW ENGINE INNODB MUTEX. Try to find in the manual all the details you may need for this.

Suggested fix:
Provide at least some specific example of what views can be created to replace SHOW ENGINE INNODB MUTEX, and how to query them.

Hello Valeriy,

Thank you for the report.

Thanks,
Umesh

This was just posted today on Percona's blog.  It looks like a good example to use:

http://www.percona.com/blog/2015/01/06/getting-mutex-information-from-mysqls-performance_s...

The following example was added to the reference manual:

https://dev.mysql.com/doc/refman/5.5/en/monitor-innodb-mutex-waits-performance-schema.html
https://dev.mysql.com/doc/refman/5.6/en/monitor-innodb-mutex-waits-performance-schema.html
https://dev.mysql.com/doc/refman/5.7/en/monitor-innodb-mutex-waits-performance-schema.html

Thank you for the bug report.