I have been testing my web application with a load of 250 simultaneous users. But i am getting a database error -
A Database Error has occured Unable to connect to the database with the following settings filename: core/loader.php
I have no idea about the reason the database goes down like this?
It sounds like you have hit the MySQL connection limit:
Add the line below to the bottom of your my.cnf and restart MySQL
max_connections = 250
You'll need to tweak this value to suit your server best - see What does max_connections really mean? and the docs for more details on how to pick this value - but 250 should be fine for your testing