maria-developers team mailing list archive

[MARK CALLAGHAN <mdcallag@xxxxxxxxx>]

Is it reasonable for semi-sync to need to lock/unlock LOCK_plugin that
frequently? The plugin architecture, like most of the rest of MySQL, wasn't
described to people on the outside (like me).


On Mon, Aug 19, 2013 at 6:32 AM, Pavel Ivanov <pivanof@xxxxxxxxxx> wrote:

> 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
>
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-- 
Mark Callaghan
mdcallag@xxxxxxxxx