maria-developers team mailing list archive

[Pavel Ivanov <pivanof@xxxxxxxxxx>]

On Mon, Aug 19, 2013 at 5:17 AM, Roberto Spadim <roberto@xxxxxxxxxxxxx> wrote:
> hi!
>
>> Another plugin that should be disabled is QUERY_RESPONSE_TIME. It has quite
>> some impact on LOCK_plugin:
>>
>> -DWITH_QUERY_RESPONSE_TIME=1
>>
>> +-----------------------------------------+------------+-----------------+
>> | event_name                              | count_star | sum_timer_wait  |
>> +-----------------------------------------+------------+-----------------+
>> | wait/synch/mutex/sql/LOCK_open          |    2743723 | 160451183703111 |
>> | wait/synch/mutex/mysys/THR_LOCK::mutex  |    2743651 |  19122327109683 |
>> | wait/synch/mutex/sql/LOCK_plugin        |    3135747 |  18611700478728 |
>> | wait/synch/rwlock/sql/LOCK_tdc          |    1356784 |   1360918935810 |
>>
>> -DWITHOUT_QUERY_RESPONSE_TIME=1
>>
>> completely removes LOCK_plugin from the top 20 list. This is also considered
>> a bug as the plugin API should be lightweight.
>>
>
> Should the
> "SET GLOBAL query_response_time_stats=0"
> solve this contention problem? or the LOCK_plugin is called always,
> doesn't matter if it's "disabled" or not?

If it's implemented the same way as semisync plugins (and it should be
implemented like that) then LOCK_plugin is locked even when plugin's
functionality disabled, because it gets disabled using plugin-specific
variable which can be checked only inside the plugin code.


Pavel