That means that user runnig your application open much more files/ connection than admitted.
To solve the problem (assure first that program also closes files correctly) follow this steps:
Count opened files and modify permission
- lsof –u <your_user> | wc -l
- lsof +p <your application process> | wc -l
Find your system settings in cat /etc/security/limits.conf
You can modify these settings editing that file at your convenience. For example:
<your_user> soft nofile 2048
<your_user> hard nofile 8192
NOTE: modify /etc/security/limits.conf doesn't require system reboot. You probably have only to restart application which can't open more files .