Programmer looking for a new language

I have been a JavaScript developer for a few years now (non professionally) and I really like the language. I mainly program for execution with NodeJS rather than web, because I feel like I get more freedom (e.i. the ability to use a computer file system).

I normally never use other people's libraries and instead either write my own library/ies for the specific task or use an old one. I only ever use someone else’s if I need a quick frame work to test an idea, never for something I will actually use.
I prefer to work object / class orientated.

I have worked on distributed servers with NodeJS before, however trying to distribute a load across one computer across it's multiple threads has proved problematic due to the heavy delays of standard io transfer speeds.

Why do I want to switch?:
•Because JavaScript is not at all created with multithreading in mind, and pretty much any multithreading solution is a bodge and allot of the time it is more efficient to work single threaded.
•Also, I get the sense that JavaScript + NodeJS is not used often in the programming industry comparison to other languages like; ruby, python, and I don't want to get stuck in a nesh language of which would decrease my employment chances heavy.

Side Note: I have been working on a pet project to have a distributed database (made with nodejs), and so far, there are no language specific problems, but I feel like it would be more efficient if I used a programming language designed more to cater for multi threading.