Hi, Sergey! Did you benchmark the improvement you get with this patch?
On Dec 05, Sergey Vojtovich wrote: > At lp:maria/10.0 > > ------------------------------------------------------------ > revno: 3915 > revision-id: [email protected] > parent: [email protected] > committer: Sergey Vojtovich <[email protected]> > branch nick: 10.0 > timestamp: Thu 2013-12-05 12:44:30 +0400 > message: > MDEV-5388 - Reduce usage of LOCK_open: unused_tables > > Removed unused_tables, find LRU object by timestamp instead. > === modified file 'sql/table_cache.cc' > --- a/sql/table_cache.cc 2013-08-27 12:12:33 +0000 > +++ b/sql/table_cache.cc 2013-12-05 08:44:30 +0000 > @@ -324,20 +248,44 @@ void tc_add_table(THD *thd, TABLE *table > DBUG_ASSERT(table->in_use == thd); > mysql_mutex_lock(&LOCK_open); > table->s->tdc.all_tables.push_front(table); > - tc_count++; > /* If we have too many TABLE instances around, try to get rid of them */ > - if (tc_count > tc_size && unused_tables) > + if (tc_count == tc_size) I'd rather put (tc_count >= tc_size), looks safer. > { > - TABLE *purge_table= unused_tables; > - tc_remove_table(purge_table); > - mysql_rwlock_rdlock(&LOCK_flush); > + TDC_iterator tdc_it; > mysql_mutex_unlock(&LOCK_open); > - intern_close_table(purge_table); > - mysql_rwlock_unlock(&LOCK_flush); > - check_unused(thd); > + > + tdc_it.init(); > + mysql_mutex_lock(&LOCK_open); > + if (tc_count == tc_size) and here > + { > + TABLE *purge_table= 0; > + TABLE_SHARE *share; I think a status variable for this would be nice. So that one could make an informed decision about the desired size of the cache. > + while ((share= tdc_it.next())) > + { > + TABLE_SHARE::TABLE_list::Iterator it(share->tdc.free_tables); > + TABLE *entry; > + while ((entry= it++)) > + if (!purge_table || entry->tc_time < purge_table->tc_time) > + purge_table= entry; > + } > + if (purge_table) > + { > + tdc_it.deinit(); > + purge_table->s->tdc.free_tables.remove(purge_table); > + purge_table->s->tdc.all_tables.remove(purge_table); > + mysql_rwlock_rdlock(&LOCK_flush); > + mysql_mutex_unlock(&LOCK_open); > + intern_close_table(purge_table); > + mysql_rwlock_unlock(&LOCK_flush); > + check_unused(thd); > + return; > + } > + } > + tdc_it.deinit(); Okay, so you only purge one table at time? Since purge is kind of an expensive operation, it's better to amortize the cost of it by purging many tables at once. > } > - else > - mysql_mutex_unlock(&LOCK_open); > + /* Nothing to evict, increment tc_count. */ > + tc_count++; > + mysql_mutex_unlock(&LOCK_open); > } > 2 Regards, Sergei _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
