[sjtgraham]

Actually not everything in Node is non-blocking. IO is largely non-blocking by but there is also blocking IO in Node too (synchronous file system functions). Not to mention you definitely will block by doing something computationally intensive in a single tick of the reactor loop.

Have you ever written a non-trivial "real time" app in Ruby? I have (https://github.com/stevegraham/slanger). I think Ruby is actually very well suited to event driven apps. Eventmachine is a very mature library providing asynchronous I/O based on the same pattern as Node. Ruby also has fibers as a native language feature, allowing you to write asynchronous code that looks synchronous, i.e. no nested callback hell, and consequently this makes it a lot easier to write tests for.

Comparing Node to Rails is also absolute nonsense. Rails is a web framework and Node is much lower level than that. Rails is essentially a suite of DSLs for building web applications. Of course there are costs associated with that amount of abstraction.

[sunkencity]

One thing that keeps me from considering Eventmachine mature is that the built in http clients are very crude and undocumented. Example: to get working error handling one needs to use an external http client library like igrigoriks em-http-request instead of the defaults. In this regard Node comes out ahead with better core utilities to boot. Stuff like that is very confusing for new users and puts the whole framework into question (shipping with a http client that is not suitable for production use).

[amix]

Having blocking computation is much better than having blocking IO - - especially, since most web applications spend most of their time waiting for the database/caching layer. And blocking computation can be solved in node using the clusters feature.