Hello Alan,
Upgrade to a recent version. This was fixed a while ago.
I'm using freeradius3-3.0.17_3 and the messages is in my log Thu Jan 31 08:14:13 2019 : Info: rlm_sql (sql): Opening additional connection (882), 1 of 29 pending slots used Thu Jan 31 08:14:24 2019 : Info: Need 2 more connections to reach 35 spares Thu Jan 31 08:14:24 2019 : Info: rlm_sql (sql): Opening additional connection (883), 1 of 28 pending slots used Thu Jan 31 08:14:56 2019 : Info: rlm_sql (sql): Closing connection (871), from 2 unused connections Thu Jan 31 08:15:09 2019 : Info: rlm_sql (sql): Closing connection (862), from 1 unused connections Thu Jan 31 08:15:24 2019 : Info: Need 1 more connections to reach 35 spares Thu Jan 31 08:15:24 2019 : Info: rlm_sql (sql): Opening additional connection (884), 1 of 29 pending slots used Thu Jan 31 08:15:56 2019 : Info: rlm_sql (sql): Closing connection (826), from 1 unused connections Any hint? Aurélio