Re: Possible stability issue: permanent hang on dropdb

On Fri, Feb 5, 2010 at 9:50 PM, The Fuzzy Chef <fuzzy(at)fuzzychef(dot)org> wrote:
> Just had a very odd thing happen with an 8.4.2 database, and am
> concerned it's an undiagnosed bug:
>
> (1) created and dropped the same database 10-15 times in the course of
> running some tests.
>
> (2) at one point, dropdb hung.  Indefinitely.
>
> (3) attempts to pg_cancel_backend on the DROP DATABASE process were
> futile.  yet no other queries were accessing that database according to
> pg_stat_activity.
>
> (4) pg_ctl -m fast did not shut down the server.
>
> (5) pg_ctl -m immediate did shut it down.
> (5a) realized pgbouncer was still running.  shut it down as well.
>
> (6) on restart, the server took several minutes to *start* recover mode.
>  then it got to a certain log segment, and hung indefinitely.
>
> (7) killed postgres
>
> (8) restarted again.  this time the server came up in about 20s, and is
> behaving normally.  The deleted database is not there.
>
> Setup:
> RHEL 5
> PostgreSQL 8.4.2, installed from yum.postgresql.org
> 8 databases and about 10G of data on the server
> pgbouncer running but NOT connected to the dropped database, just to two
> others
>
> I've made a full copy of my PGDATA directory if anyone wants me to test
> anything.

It's too bad you didn't capture a stack backtrace at step #3 or step
#6. If you manage to reproduce the problem, that would be a good
thing to try to get.

...Robert