jRuby and Rubinius support parallel computing, but what about gems that don't support this?

Question

What I'm trying to understand is, practically speaking, how much benefit do I get from the parallel computing support in jRuby / Rubinius? A lot of ruby libraries keep track of global internal state. Is there any way to deal with these libraries, or do they just become unusable if I decide to parallelize my Ruby script? Maybe Rubinius automatically puts a mutex in front of all usage of unsafe libraries?

Answer 1

Whenever you want to use jruby or rubinius, you'll be forced to use gems that are compatible.
Many gems has been implemented using C extensions and you can not use them along jruby e.g.
Regarding others, mostly they clearly states their thread safety status.

So choosing jruby or rubinius will narrow down your options regarding the gems. but a huge opportunity will be exposed, you'd be able to use many mature Java Libraries(in jruby case).