On Jun 30, 2014, at 4:57 PM, Jeff Frost <j...@pgexperts.com> wrote: > > On Jun 30, 2014, at 4:04 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > >> Ah ... that's more like a number I can believe something would have >> trouble coping with. Did you see a noticeable slowdown with this? >> Now that we've seen that number, of course it's possible there was an >> even higher peak occurring when you saw the trouble. >> >> Perhaps there's an O(N^2) behavior in StandbyReleaseLocks, or maybe >> it just takes awhile to handle that many locks. >> >> Did you check whether the locks were all on temp tables of the >> ON COMMIT DROP persuasion? > > > Unfortunately not, because I went for a poor man's: SELECT count(*) FROM > pg_locks WHERE mode = 'AccessExclusiveLock' > run in cron every minute. > > That said, I'd bet it was mostly ON COMMIT DROP temp tables. > > The unfortunate thing is I wouldn't know how to correlate that spike with the > corresponding slowdown because the replica is about 5.5hrs lagged at the > moment. > > Hopefully it will get caught up tonight and we can see if there's a > correlation tomorrow.
And indeed it did catch up overnight and the lag increased shortly after a correlating spike in AccessExclusiveLocks that were generated by temp table creation with on commit drop.
