Seems like kind of apples-to-oranges to me as well.... Threaded, done right (which isn't always easy) - can scale on a single machine to use up all the cores

Seems like kind of apples-to-oranges to me as well.... Threaded, done right (which isn't always easy) - can scale on a single machine to use up all the cores you can throw at it. This can be fairly optimal on the machine in question, depending on the app. Traditionally when dealing with threaded programming you have a whole lot of locking and whatnot to keep track of - and things can get ugly fast. It's HARD. And all that hard work, while it might help you scale up to the biggest multi-processor beast you can find - doesn't help you one bit when it comes to scaling horizontally to multiple nodes..... I'd wager, depending on the situation, that it gets right up in your face and in the way. But tha'ts back to comparing apples and oranges. "scalable" is about overall design - what needs to talk to what, how will it scale, will it be a purely shared-nothing environment like erlang where we're passing messages and can scale out horizontally like mad, but where every function call is effectively a full memory copy, possibly over a network? Or do we nail it down to a precisely crafted C++ threaded app that our expert designers know down to it's finest detail, that's faster than sh*t througha goose, and hey, it uses some evented stuff as well. It seems the real rise interest in the event-driven nature of node.js is that it makes it obvious to even beginner programmers where the difference is - you are setting up some actions, and letting the OS kernel handle listening for the events for you in the fastest possible way. You could do all that on your own in another language, but here it is all neatly wrapped up, in a language you already know.