[ruby-core:47562] feature request: thread pool class

It has always seemed a bit odd to me that Ruby's sdlib doesn't have some kind of
threadpool class.

I know it's easy to roll your own, but it would be slightly easier to
be able to do something like

a = [1,2,3]
ThreadPool.new(a).map{|number|
 number*3
}

Or the lik.
Feedback welcome. If none I'll file a feature request redmine.

Thank you.
-roger-
related: http://stackoverflow.com/questions/3840751/why-doesnt-ruby-have-a-threadpool-built-in/3841111#3841111