On Fri, Jul 15, 2011 at 08:22, Scott Marlowe <scott.marl...@gmail.com>wrote:
> On Thu, Jul 14, 2011 at 6:01 PM, Tony Wang <www...@gmail.com> wrote: > > On Fri, Jul 15, 2011 at 01:13, Scott Marlowe <scott.marl...@gmail.com> > > wrote: > >> > >> On Wed, Jul 13, 2011 at 9:47 PM, Tony Wang <www...@gmail.com> wrote: > >> > On Thu, Jul 14, 2011 at 10:35, John R Pierce <pie...@hogranch.com> > >> > wrote: > >> > It's a game server, and the queries are updating users' money, as > >> > normal. > >> > The sql is like "UPDATE player SET money = money + 100 where id = > >> > 12345". > >> > The locks were RowExclusiveLock for the table "player" and the > indexes. > >> > The > >> > weird thing is there was another ExclusiveLock for the table "player", > >> > i.e. > >> > "player" got two locks, one RowExclusiveLock and one ExclusiveLock. > >> > In the postgresql documentation > >> > (http://www.postgresql.org/docs/8.4/static/explicit-locking.html), > it's > >> > said > >> > about the Exclusive "This lock mode is not automatically acquired on > >> > user > >> > tables by any PostgreSQL command." > >> > >> You need to figure out what part of your app, or maybe a rogue > >> developer etc is throwing an exclusive lock. > > > > Yeah, that's what I'm trying to do > > Cool. In your first post you said: > > > select pg_class.relname, pg_locks.mode, pg_locks.granted, > pg_stat_activity.current_query, pg_stat_activity.query_start, > > pg_stat_activity.xact_start as transaction_start, > age(now(),pg_stat_activity.query_start) as query_age, > > age(now(),pg_stat_activity.xact_start) as transaction_age, > pg_stat_activity.procpid from pg_stat_activity,pg_locks left > > outer join pg_class on (pg_locks.relation = pg_class.oid) where > pg_locks.pid=pg_stat_activity.procpid and > > substr(pg_class.relname,1,3) != 'pg_' order by query_start; > > > The only special thing I can find is that there were a lot ExclusiveLock, > while it's normal the locks are > > only AccessShareLock and RowExclusiveLock. > > So what did / does current_query say when it's happening? If it says > you don't have access permission then run that query as root when it > happens again. > As I said, it's normal update like "UPDATE player SET money = money + 100 WHERE id=12345", but there are quite many
