Re: too many clients already

"Abraham, Danny" <danny_abraham@bmc.com> writes:
> Running on a big and stressed AIX platform and receiving lots of "CDTFATAL:  sorry, too many clients already"
> and transient difficulty to log in.
> Happens on all PG versions (Tested 9.5,10.4,11.5)
> Big installation: max_connections is 1200,  shared_buffers is 2GB
> But .. select count(*) from pg_stat_activity   is only 66.

I'd be suspicious that there are a lot of clients stuck in connection
startup (likely the authentication phase); those connections aren't going
to show in pg_stat_activity until they finish connecting.  The "ps"
suggestion Adrian gave you would not show them either, because they're
not going to say "idle".

Enabling log_connections and watching the postmaster log would help
prove or disprove that theory.

            regards, tom lane