Re: autovacuum causing numerous regression-test failures

http://www.pgbuildfarm.org/cgi-bin/show_log.pl?nm=osprey&dt=2006-08-28%2016:00:17
shows another autovac-induced failure mode:

! psql: FATAL:  sorry, too many clients already

initdb is choosing max_connections = 20 on this machine, which is
sufficient to run the parallel regression tests by themselves,
but not regression tests plus autovac.

IIRC initdb will go down to 10 or so connections before deciding
it's hopeless.  I don't really want to change that behavior because
it might make it impossible to initdb at all on a small machine.
But probably there needs to be a way for pg_regress to set a floor
on the acceptable max_connections setting while initializing the
test instance for "make check".

This also ties into the recent discussions about whether autovac needs
its own reserved backend slots.  Which, again, sounds to me like a fine
idea for 8.3 work.
        regards, tom lane