Check out this webinar from the guy who wrote the book on Grails Dave Klein and and learn about it for yourself:
Monday, April 26, 2010
Dave Klein's Scale Grails Webinar
As someone who spent years in the Smalltalk world I have a special place in my heart for powerful/flexible frameworks and languages that strive for simplicity for the developer. Grails is one of the most powerful and flexible frameworks around and modern representation of those Smalltak values. Some would argue that it's only major missing features are scale-out and HA. The great news on that front is that Grails is built on Quartz, Ehcache, Http Sessions and Hibernate all of which can be scaled with Terracotta in a couple lines of config each. By scaling these four frameworks you can completely scale Grails.