Re: autovacuum launcher using InitPostgres

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Tom Lane wrote:
>> Well, I'm not sure the average user knows or cares about the difference
>> between the launcher and the workers.  The thing that was in the back of
>> my mind was that we would now have the option to have the launcher show
>> up in pg_stat_activity.  If we were to do that then the case for
>> counting it in the user-visible number-of-processes parameter would get
>> a lot stronger (enough to justify renaming the parameter, if you insist
>> that the launcher isn't a worker).  I don't however have any strong
>> opinion on whether we *should* include it in pg_stat_activity ---
>> comments?

> The user may not care about the difference, but there's a point in
> having the limit be the simpler concept of "this is the maximum amount
> of processes running vacuum at any time".  The launcher is very
> uninteresting to users.

I committed things that way, but I'm still not convinced that we
shouldn't expose the launcher in pg_stat_activity.  The thing that
is bothering me is that it is now able to take locks and potentially
could block some other process or even participate in a deadlock.
Do we really want to have entries in pg_locks that don't match any
entry in pg_stat_activity?
        regards, tom lane