Concurrency and parallelism are extremely important for performance in this multi-core age. Effective use of concurrency requires substantial understanding of the underlying principles and details. Fortunately, Clojure provides safe and elegant ways to deal with concurrency and state. Clojure's new feature called "reducers" provides a way to achieve granular parallelism. In the coming years, we are likely to see more and more processor cores, and an increasing demand to write code that takes advantage of these. Clojure places us in the right spot to meet such challenges.

In the next chapter, we will look at the performance measurement, analysis, and monitoring.