I am not familiar at all with connection pooling library. I’ve just discovered it through this blog article) and I am not sure that I should use one in my web application based on grails/hibernate/mysql.
So my question is simple : in which situations would you suggest to integrate a connection pooling library into a grails application? Always, Never or only over some connections threshold?
P.S. : If you have ever used successfully C3P0 in your web application, I will greatly appreciate to hear your feedback (in terms of visible positive effects).
Regardless of which pooling implementation, you should use a connection pool always in your web application. Open a connection with the database is a very expensive task and being able to reuse a already existing and idle connection greatly improves your site performance.
A connection can be managed by the application server (Tomcat, JBoss, Glassfish…) or by your application. The latter is easier to setup but it’s hard to customize per deployment. Configuring a connection pool on the application and setting your site to consume it makes easy to the fine tune the connection pool parameters, like: minimum connections to keep open, max idle time and so on.