On 2013-12-06 07:22:27 +0100, Pavel Stehule wrote:
> I have a report of critical bug (database is temporary unavailability ..
> restart is necessary).

> PostgreSQL 9.2.4,
> 24 CPU
> 140G RAM
> SSD disc for all
> Database is under high load. There is a few databases with very high number
> of similar simple statements. When application produce higher load, then
> number of active connection is increased to 300-600 about.
> In some moment starts described event - there is a minimal IO, all CPU are
> on 100%.
> Perf result shows:
>            354246.00 93.0% s_lock
> /usr/lib/postgresql/9.2/bin/postgres
>             10503.00  2.8% LWLockRelease
>  /usr/lib/postgresql/9.2/bin/postgres
>              8802.00  2.3% LWLockAcquire

> We try to limit a connection to 300, but I am not sure if this issue is not
> related to some Postgres bug.

We've seen this issue repeatedly now. None of the times it turned out to
be a bug, but just limitations in postgres' scalability. If you can I'd
strongly suggest trying to get postgres binaries compiled with
-fno-omit-frame-pointer installed to check which locks are actually
My bet is BufMappingLock.

There's a CF entry about changing our lwlock implementation to scale


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:

Reply via email to