Обсуждение: autovacuum cannot start when connection is full

Hi hackers,

Autovacuum uses connections in superuser mode. If all connections are used,
autovacuum cannot start and the following message is written in server log.
| FATAL:  sorry, too many clients already

Is this a feature?

The default value of 'superuser_reserved_connections' is 2, so maybe
few people have seen it. Autovacuum can always start in normal use.
(I found it when I tried to make multi-processed autovacuum.)

Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center

ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp> writes:
> Autovacuum uses connections in superuser mode. If all connections are used,
> autovacuum cannot start and the following message is written in server log.
> | FATAL:  sorry, too many clients already

> Is this a feature?

Yes.

I coulda sworn there was a specific mention in the docs that you'd
better allow for autovac when choosing superuser_reserved_connections,
but a quick grep doesn't find it.
        regards, tom lane

On 8/25/06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I coulda sworn there was a specific mention in the docs that you'd
> better allow for autovac when choosing superuser_reserved_connections,
> but a quick grep doesn't find it.

There is a mention in autovacuum doc:
http://www.postgresql.org/docs/8.1/interactive/maintenance.html#AUTOVACUUM

Last sentence of the first paragraph is:
"Also, it's important to allow a slot for the autovacuum process when
choosing the value of superuser_reserved_connections."

--
Guillaume

"Guillaume Smet" <guillaume.smet@gmail.com> wrote:

> There is a mention in autovacuum doc:
> http://www.postgresql.org/docs/8.1/interactive/maintenance.html#AUTOVACUUM
> 
> Last sentence of the first paragraph is:
> "Also, it's important to allow a slot for the autovacuum process when
> choosing the value of superuser_reserved_connections."

Thank you!

It may be as well to add the same mention to the description of
superuser_reserved_connections.
| Determines the number of connection "slots" that are reserved for connections
| by PostgreSQL superusers, *including autovacuum*.

Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center