Running CPU-bound tasks

The totalSales() API, even though expensive in terms of resources, was not affecting the ability of the server to accept concurrent requests. What we learned in Chapter 1, Node.js Design Fundamentals, about the event loop should provide an explanation for this behavior: invoking an asynchronous operation causes the stack to unwind back to the event loop, leaving it free to handle other requests.

However, what happens when we run a long, synchronous task that never gives back the control to the event loop? This kind of task is also known as CPU-bound, because its main characteristic is that it is heavy on CPU utilization rather than being heavy on I/O operations.

Let's work immediately on an example to see how these types of tasks behave in Node.js.

Solving the subset sum problem

Let's now choose a computationally expensive problem to use as a base for our experiment. A good candidate is the subset sum problem that consists of deciding whether a set (or multiset) of integers...