Обсуждение: Why threads every 30 seconds?

Looking at audit logs, I see that my Postgresql server generates a new thread
precisely every 30 seconds, in two series (so 4 threads every minute).  This
is an otherwise idle server.

Does anyone know what these threads are for?  Just curious.

--
Bryan Henderson                                   San Jose, California

Bryan Henderson <bryanh@giraffe-data.com> writes:
> Looking at audit logs, I see that my Postgresql server generates a new thread
> precisely every 30 seconds, in two series (so 4 threads every minute).  This
> is an otherwise idle server.

> Does anyone know what these threads are for?  Just curious.

Autovacuum, likely.  The rate would depend on your autovacuum_naptime
and how many active databases you have.

            regards, tom lane

>>> Looking at audit logs, I see that my Postgresql server generates a new thread
>>> precisely every 30 seconds, in two series (so 4 threads every minute).  This
>>> is an otherwise idle server.
>
>>> Does anyone know what these threads are for?  Just curious.
>
>Autovacuum, likely.  The rate would depend on your autovacuum_naptime
>and how many active databases you have.

Yep, that was it, thanks.

I had the default autovacuum_naptime of 1 minute, and had two Postgresql
clusters runing.  I turned off autovacuum and these threads disappeared.

Still not sure how it comes to twice a minute per cluster.  There are 5
databases, and as far as I know, a client connection to one of them, not
doing anything, while this was happening.

--
Bryan Henderson                                   San Jose, California