On 14/04/16 18:34, Kevin Burke wrote:
Unfortunately *I'm still seeing a very slow query which is affecting
our tests. *It's happening with roughly the same frequency as the
previous error.
*
*
The query log is here:
https://gist.github.com/kevinburkeshyp/f1a4f73f8933e027aebbc53283acced2**
*
*
In the log, it looks like an INSERT on the users table takes about 23
seconds. This query is connecting from Javascript to a Postgres server
on the same machine. After 18 seconds, the test performing the INSERT
times out, we try to clear the database, and then the next test runs.
The next test also attempts to INSERT a record, but is blocked on the
first INSERT. After 5 more seconds, the first INSERT completes, and
the second INSERT is allowed to run.
2016-04-14 00:46:54.649 UTC 2016-04-14 00:46:34 UTC
[14308-570ee86a.37e4-42] 00000 ubuntu@circle_test LOG: process 14308
still waiting for ExclusiveLock on extension of relation 17215 of
database 16387 after 1000.104 ms
2016-04-14 00:46:54.649 UTC 2016-04-14 00:46:34 UTC
[14308-570ee86a.37e4-43] 00000 ubuntu@circle_test DETAIL: Process
holding the lock: 14260. Wait queue: 14308.
2016-04-14 00:46:58.979 UTC 2016-04-14 00:46:34 UTC
[14308-570ee86a.37e4-45] 00000 ubuntu@circle_test LOG: process 14308
acquired ExclusiveLock on extension of relation 17215 of database
16387 after 5330.117 ms
Between the last time I emailed and now, I also disabled autovacuum on
the server; it seemed unnecessary if we are issuing ~10k queries tops,
and generating ~100k records tops, in the course of a test run.
However, I didn't see any other queries or log messages (e.g. "kicking
off autovacuum") that would have indicated a problem.
Here's the schema on the table that generated the 23-second long
INSERT:
https://gist.github.com/kevinburkeshyp/5a40d372b6aa1e1426801d8195cb0b61
Any ideas why an INSERT on an empty table, to a low-load server
running on the same machine, with no other queries being generated
during that time, could take 23 seconds to complete? The server is
running Postgres 9.4.6.
What other information do I/you need to figure out what's going on?
Hello Kevin,
It would be nice if you could determine the names of the relations and
queries for the processes mentioned in the log message quoted.
For relations simply cast the oid (numbers) to regclass, for processes
please query pg_stat_activity.
Have you tried to turn autovacuum on?
Regards,
Alexey
