On 2015-01-14 10:05:01 -0500, Tom Lane wrote: > Merlin Moncure <mmonc...@gmail.com> writes: > > On Wed, Jan 14, 2015 at 8:41 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > >> What are the autovac processes doing (according to pg_stat_activity)? > > > pid,running,waiting,query > > 7105,00:28:40.789221,f,autovacuum: VACUUM ANALYZE pg_catalog.pg_class
It'd be interesting to know whether that vacuum gets very frequent semaphore wakeups. Could you strace it for a second or three? How did this perform < 9.4? Can you guess how many times these dynamic statements are planned? How many different relations are accessed in the dynamically planned queries? > Hah, I suspected as much. Is that the one that's stuck in > LockBufferForCleanup, or the other one that's got a similar backtrace > to all the user processes? Do you have a theory? Right now it primarily looks like contention on a single buffer due to the high number of dynamic statements, possibly made worse by the signalling between normal pinners and vacuum waiting for cleanup. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
