"List" is referred to as the most basic collection. It has an undetermined number of elements, and you can add, read, or remove an element from any position. Concurrent lists allow various threads to add or remove elements from the list at a time, without producing any data inconsistency errors. Similar to lists, we have deques. A deque is a data structure similar to a queue, but in a deque, you can add or remove elements from either the front (head) or back (tail).

In this recipe, you will learn how to use a non-blocking deque in a concurrent program. Non-blocking deques provide operations that, if not done immediately (for example, you want to get an element from a list but the list is empty), throw an exception or return a null value, depending on the operation. Java 7 introduced the ConcurrentLinkedDeque class that implements a non-blocking concurrent deque.

We are going to implement an example with the following two different tasks:

• One that adds thousands of elements to the deque
• One that removes data from the deque