It been a while since i played with Rails so was surprised to hear that Rails is now multithreaded. Has any one here deployed Rails in this configuration and is it stable?
I love the idea of this since it would save a shitload of RAM on our app which has mongrels pushing 500MB. But realistically it scares me because in Ruby you can do so many things that aren't threadsafe. Rails being threadsafe is all fine and dandy, but unless you know what you're doing and audit your code thoroughly, it's probably pretty risky for an existing application (to say nothing of various gems).
The point is that Java webapps are multihreaded. Classic Ruby apps require dedicated process for every parallel request. Hence your 4GB java app may still be more efficient than 500MB Mongrels.
4 gigs for a search index is rather meaningless. It's based on the size and number of documents you need to index, and not so much on your language or tool of choice.
Correct. But the lucene index requirement was bounded by the fixed size of a CMS. There were ~5k products and they were aggregating consumer reviews from various sites. The 4GB was not an strict limit, but it was what we needed to store all the user reviews of all the products, allowing for up to 20 reviews per product.