AWS RDS PostgreSQL error “remaining connection slots are reserved for non-replication superuser connections”

Amazon has to set the number of connections based on each model’s right to demand a certain amount of memory and connections

MODEL      max_connections innodb_buffer_pool_size
---------  --------------- -----------------------
t1.micro   34                326107136 (  311M)
m1-small   125              1179648000 ( 1125M,  1.097G)
m1-large   623              5882511360 ( 5610M,  5.479G)
m1-xlarge  1263            11922309120 (11370M, 11.103G)
m2-xlarge  1441            13605273600 (12975M, 12.671G)
m2-2xlarge 2900            27367833600 (26100M, 25.488G)
m2-4xlarge 5816            54892953600 (52350M, 51.123G)

But if you want you can change the max connection size to custom by

From RDS Console > Parameter Groups > Edit Parameters,

You can change the value of the max_connections parameter to a custom value.

For closing the connections periodically you can setup a cron job some thing like this.
[code type=sql]
select pg_terminate_backend(procpid)
from pg_stat_activity
where usename = ‘yourusername’
and current_query = ‘
and query_start < current_timestamp - interval '5 minutes';