Mutex contention from various plugins
On Tue, Aug 20, 2013 at 9:12 AM, Pavel Ivanov <piva...@google.com> wrote: > Workaround for which problem? > > On Tue, Aug 20, 2013 at 8:17 AM, MARK CALLAGHAN <mdcal...@gmail.com> > wrote: > > Is the workaround to use static rather than dynamic plugins? > > > > > > On Tue, Aug 20, 2013 at 7:31 AM, Sergei Golubchik <s...@mariadb.org> > wrote: > >> > >> Hi, Pavel! > >> > >> On Aug 20, Pavel Ivanov wrote: > >> > On Tue, Aug 20, 2013 at 1:09 AM, Sergei Golubchik <s...@mariadb.org> > >> > 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 > >> > >> _______________________________________________ > >> Mailing list: https://launchpad.net/~maria-developers > >> Post to : maria-developers@lists.launchpad.net > >> Unsubscribe : https://launchpad.net/~maria-developers > >> More help : https://help.launchpad.net/ListHelp > > > > > > > > > > -- > > Mark Callaghan > > mdcal...@gmail.com > -- Mark Callaghan mdcal...@gmail.com
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