This is the Smart Shutdown mode. After receiving SIGTERM, the server disallows new connections but lets existing sessions end their work normally. It shuts down only after all of the sessions terminate. If the server is in online backup mode, it additionally waits until the online backup mode is no longer active. While the backup mode is active, new connections will still be allowed, but only to superusers (this exception allows a superuser to connect to terminate the online backup mode). If the server is in recovery when a smart shutdown is requested, recovery and streaming replication will be stopped only after all regular sessions have terminated.