Solving concurrent problems using Clojure

In this recipe, we will learn Clojure's atoms, refs, and agents. Then we will have a look at Clojure's parallel features.

Getting ready

In this recipe, we will not use an external library. So, the only necessary thing is to start REPL to run code.

How to do it...

Clojure provides solutions for the concurrency problem. Clojure's vars defined in def are ensured only in single thread and are not safe in concurrent environments. Clojure provides three types of resources for concurrent problem. Here, we will introduce you atoms, refs, and agents that work in concurrent environments.

Using atoms

Atoms provide a way to manage shared, synchronous, and independent states.

Creating and referring atom

The atom function sets the initial value to atom. The following code initializes the atom to 1 and sets the atom to the var x:

(def x (atom 1)) 
;;=? #'chapter06.concurrency/x 

So, the value of x binds to Atom instance:

x 
;;=> #<Atom@541e8f8d: 1> 

To see the values...