“Is language X scalable? I heard that it isn’t”

A nonsensical question that is rarely qualified.

To quote Theo from his fine book

Languages aren’t slow; implementations of languages are.

and

Language selection and scalability have little to do with each other; architectural design and implementation strategy dictate how scalable a final product will be.

I couldn’t have put it better myself.

The point is simple.

Just because a given language may be slower (note the “er”, that makes this a relative term) in parsing XML doesn’t mean that

  1. it’s fundamentally slow (an absolute term),
  2. that as part of a web stack it can’t do 10,000 requests/second, and
  3. simply tells you something about it’s performance in a given situation not about it’s “scalability”.

In case you’re wondering, I just got off a call where I was asked this question not about Ruby but about Java. Interesting.