Is there any utility to restart a rails server automatically in case of exception occurred i.e.
forever is the utility through which
node.js can be started automatically.
You can use Passenger for production deployments of your Rails applications. It's already a battle tested Rails solution, which is known for simplicity and good reliability. You don't need to worry about crashes, which will be handled automatically.
It provides integration with Apache and Nginx servers.
It also comes with free (community) license.
Enterprise edition gives you more feature, like uninterrupted deployments and rollbacks to last stable version.
They claim usage on 350,000 websites. So you will be in a good company.