Re: pg_autovacuum start-script

Thomas F.O'Connell wrote:
> On Aug 27, 2004, at 3:37 PM, Matthew T. O'Connor wrote:
>> pg_autovacuum will exit when it can no longer connect to a postmaster.
>> The problem is that it might sleep for several minutes before it
>> notices that the postmaster has shutdown.  So, you can restart the
>> postmaster and as long as pg_autovacuum never noticed that it went
>> away, it will keep chugging along as if nothing happened.
>>
>> Is there anyway pg_autovacuum can know if the postmaster has
>> restarted?  New PID? Or something better?
>
> Hmm. If the above situation is true, does it matter whether
> pg_autovacuum knows whether the postmaster restarted?

The issue is knowing if you need to launch another pg_autovacuum
process, you certainly don't want to have two pg_autovacuum processes
running against the same server.

>>> Is this logic sufficiently sane?
>>
>> Well if the script also sends a kill signal to pg_autovacuum that
>> might solve the pg_autovacuum still running problem.
>
> Based on what you say above, though, is it even necessary to kill it?
> Why not just observe that it's running and fail to start a new one?
> Unless there's a need to restart pg_autovacuum if postmaster restarts.

Perhaps not as long as you can reliably observe that it's running
against the newly started postmaster and not another pg_autovacuum
process running against an entirely separate postmaster process.