I am talking about the cultures surrounding these languages and frameworks. Node's community rejects blocking libraries. Java's does not. I've used the non-blocking frameworks in Perl (POE and my own), C (select, and some of the poll variants), Ruby (event machine) and they are fine if you can avoid blocking libraries -- in these communities it is generally acceptable to write blocking libraries. I don't see it as a technical hurdle, I see it as a cultural one.
You need to start backing up your claims with actual data. What networking libraries are blocking in Node.js that are not blocking in Twisted? Moreover, what can't you do with a Twisted Deferred that you can do in Node.js?
There are two main things that block in computing:
* I/O
* CPU
You better believe that Node blocks on CPU, so what I/O does Node not block on that Twisted does?
I am talking about the cultures surrounding these languages and frameworks. Node's community rejects blocking libraries. Java's does not.
So what?
You get tons of Java libs to use, a majority of blocking ones and lots of non blocking on one hand, or you restrict yourself to the fewer non-blocking libs of varying quality available for Node.
With Java you can also turn blocking libs to non blocking with a wrapper and threads, whereas with Node.js if it's blocking you're screwing, because the js engine is single-threaded.
