Immutability as a means of achieving concurrency

In this recipe, you will learn how to use immutability against problems caused by concurrency. 

 

Getting ready

A concurrency problem most often occurs when different threads modify and read data of the same shared resource. Decreasing the number of modifying operations diminishes the risk of concurrency issues. This is where immutability—the condition of read-only values—enters the stage. 

Object immutability means an absence of means to change its state after the object has been created. It does not guarantee thread-safety but helps to increase it significantly and provide sufficient protection from concurrency problems in many practical applications. 

Creating a new object instead of reusing an existing one (by changing its state via setters and getters) is often perceived as an expensive approach. But with the power of modern computers, there has to be a huge number of object creations done for performance to be affected in any significant...