Well, I guess the questions is - how do I optimize PG for a stream of very short life checks... See below: 2020-04-02 11:05:37.010 CDTLOG: connection received: host=10.64.72.157 port=45799 2020-04-02 11:05:37.014 CDTLOG: connection received: host=10.64.72.157 port=45814 2020-04-02 11:05:37.014 CDTLOG: connection received: host=10.64.72.157 port=45813 2020-04-02 11:05:37.018 CDTFATAL: sorry, too many clients already 2020-04-02 11:05:37.015 CDTLOG: connection received: host=10.64.72.157 port=45815 2020-04-02 11:05:37.015 CDTLOG: connection received: host=10.64.72.157 port=45817 2020-04-02 11:05:37.015 CDTLOG: connection received: host=10.64.72.157 port=45809 2020-04-02 11:05:37.015 CDTLOG: connection received: host=10.64.72.157 port=45818 2020-04-02 11:05:37.016 CDTLOG: connection received: host=10.64.72.157 port=45819 2020-04-02 11:05:37.021 CDTFATAL: sorry, too many clients already 2020-04-02 11:05:37.021 CDTFATAL: sorry, too many clients already 2020-04-02 11:05:37.021 CDTFATAL: sorry, too many clients already 2020-04-02 11:05:37.021 CDTFATAL: sorry, too many clients already 2020-04-02 11:05:37.021 CDTFATAL: sorry, too many clients already 2020-04-02 11:05:37.022 CDTFATAL: sorry, too many clients already 2020-04-02 11:05:37.022 CDTFATAL: sorry, too many clients already -----Original Message----- From: Tom Lane <tgl@xxxxxxxxxxxxx> Sent: Thursday, April 02, 2020 6:52 PM To: Abraham, Danny <danny_abraham@xxxxxxx> Cc: pgsql-general@xxxxxxxxxxxxxx Subject: [EXTERNAL] Re: too many clients already "Abraham, Danny" <danny_abraham@xxxxxxx> 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
