What does it mean to say that a framework “scales well”?

Question

When reading about frameworks (.net. ruby on rails, django, spring, etc.), I keep seeing so and so does or doesn\'t scale well.

What does it mean when someone says that

Answer 1

There are a few elements to it in my mind. The first is the obvious one -- performance scaling. Can your framework be used to build hight capacity, high throughput system or can it just be used to build smaller applications. Will it scale vertically on hardware (parallel libraries for example) and will it scale horizontally (web farms, for example).

The second is can it scale to larger teams or the enterprise. That is, does it work well with large code bases? Large development teams? Does it have good tool support? How easy is it to deploy? Can you roll out to tens or hundreds or even thousands of users? All the way down to is it easy to hire people that have this skill. Think of trying to put together a development team of 20 or 50 people that all work on this framework. Would it be easy or next to impossible?