On Mon, May 27, 2013 at 10:56 AM, 高健 <luckyjackgao@gmail.com> wrote:
> Hi:
> Thanks for Jov's reply.
> I traced it again, and found they are really for autovacuum.
> I found that
> some will call proc_exit() from within AutoVacLauncherMain function,
> some will call proc_exit() from within AutoVacWorkerMain function.
>
> But I wonder why not using only a few daemon , instead of making those
> processes be short life.
The short lived processes are autovacuum "worker" processes which need
to exit as soon as their work is done. There does exist a daemon
called autovacuum launcher, which periodically forks autovacuum worker
processes to perform vacuum activity. You might want to read more
about them here:
http://www.postgresql.org/docs/9.2/static/routine-vacuuming.html#AUTOVACUUM
--
Amit Langote