maria-developers team mailing list archive

[MARK CALLAGHAN <mdcallag@xxxxxxxxx>]

Is the workaround to use static rather than dynamic plugins?


On Tue, Aug 20, 2013 at 7:31 AM, Sergei Golubchik <serg@xxxxxxxxxxx> wrote:

> Hi, Pavel!
>
> On Aug 20, Pavel Ivanov wrote:
> > On Tue, Aug 20, 2013 at 1:09 AM, Sergei Golubchik <serg@xxxxxxxxxxx>
> wrote:
> > > On Aug 19, Pavel Ivanov wrote:
> > >> No, it's not reasonable for semi-sync to lock/unlock LOCK_plugin.
> > >> It's plugin infrastructure that does that.
> > >>
> > >> I've actually was terrified to learn that each call into semi-sync
> > >> plugin is surrounded with pthread_rwlock_rdlock/
> > >> pthread_rwlock_unlock (which is not cheap I believe). And also for
> > >> each such call it "locks"/"unlocks" the semi-sync plugin. And
> > >> although "locking" plugin avoids locking LOCK_plugin when plugin is
> > >> linked statically, "unlocking" doesn't do that.
> > >
> > Sure, but macro FOREACH_OBSERVER inside rpl_handler.cc doesn't use
> > this function. It uses plugin_unlock_list() which always locks
> > LOCK_plugin.
> >
> > BTW, MariaDB still supports compiling semi-sync plugins dynamically,
> > but it seems that it doesn't do anything against unloading semi-sync
> > plugins in the middle of transactions. Did anyone think about this?
>
> Judging from the replication plugin API - I don't think so.
>
> But if it adds that much overhead, I suppose we'll need to fix it.
> Then we fix the unloading too.
>
> Regards,
> Sergei
>
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-- 
Mark Callaghan
mdcallag@xxxxxxxxx