Bug #76460 Cost constant cache's mutex not instrumented by performance schema

Submitted: 23 Mar 2015 13:01 Modified: 8 Apr 2015 13:31
Reporter: Olav Sandstå Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Optimizer Severity:S3 (Non-critical)
Version:5.7.5 OS:Any
Assigned to: CPU Architecture:Any

[23 Mar 2015 13:01] Olav Sandstå 
Description:
The mutex used by the Cost Constant cache is not instrumented by performance schema. This mutex is definced in opt_costconstantcache.h as Cost_constant_cache::LOCK_cost_const. In mysqld.cc a performance schema key is defined for this mutex (key_LOCK_cost_const) but this is not used for adding the mutex to the list of instrumented mutexes.

How to repeat:
Found by code reading.

Suggested fix:
Include the mutex in the list of mutexes that are instrumented by performance schema.
[8 Apr 2015 13:31] Paul DuBois 
Noted in 5.7.8, 5.8.0 changelogs.

The mutex used for the optimizer cost model cost-constant cache was
not instrumented by the Performance Schema. This instrument is now
available as
wait/synch/mutex/sql/Cost_constant_cache::LOCK_cost_const.

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