Combining Node JS and Python for CPU and IO intensive web applications
You could use a messaging queue such as RabbitMQ.
Node JS seems to be a perfect fit for serving fast lightweight requests asynchronously. However, i'm not convinced that it is a good fit for intensive background work - despite the ability to deploy Node JS in a clustered fashion. 
I am considering using Node JS to interact with my template rendering engine (Express) and serve requests by building up a range of lightweight micro-services in Node. Further, I am then considering having Node JS pass off intensive work to Python (perhaps via some kind of in-memory technology such as Redis or a dedicated Task Queue). I am familiar with Python and in particular, multi-threading.
For example, on a 4 core machine, I might have two cores dedicated to running load balanced background tasks and 2 cores dedicated to a Node JS cluster. Would this be a vaguely sensible approach in comparison to trying to "Javascript all the things"?