Diagnosing Postgres connection exhaustion (too many clients already)
PostgreSQLrevision 1
Diagnostic tree
In progressNew connections are being refused with 'too many clients already'Postgres has a hard `max_connections` ceiling; once every slot is in use, every further connection attempt is rejected at the protocol level, before authentication even completes.
View the whole map (8 more steps)
Check whether you're actually at max_connections
Check for connections stuck idle in an open transaction
Not actually at the connection limit
Application code is leaving transactions open
Genuine concurrency is exceeding max_connections
Free the stuck connections, then stop the leak
Confirm there's real headroom again
Resolved
What to test
New connections are being refused with 'too many clients already'
Postgres has a hard `max_connections` ceiling; once every slot is in use, every further connection attempt is rejected at the protocol level, before authentication even completes.