How does CopyOnWriteArrayList impact performance or memory usage?

CopyOnWriteArrayList is a thread-safe variant of ArrayList designed for concurrent programming in Java. It achieves its thread-safety by creating a fresh copy of the underlying array whenever a modification operation (like add, set, or remove) is performed. While this provides safe read operations with minimal contention, it can significantly impact performance and memory usage under certain conditions.

The benefits of using CopyOnWriteArrayList include:

Safe for concurrent reads without locking.
Ideal for scenarios where reads greatly outnumber writes.

However, its drawbacks include:

High memory consumption due to creating a new copy of the array with each write operation.
Performance degradation when there are frequent modifications, since each modification incurs the overhead of copying the array.

It is crucial to assess usage patterns before selecting CopyOnWriteArrayList, as it is generally most efficient in read-heavy environments.


        // Example usage of CopyOnWriteArrayList in Java
        import java.util.concurrent.CopyOnWriteArrayList;

        public class Main {
            public static void main(String[] args) {
                CopyOnWriteArrayList list = new CopyOnWriteArrayList<>();
                list.add("Item 1");
                list.add("Item 2");
                
                // Reading can be done safely without locking
                for (String item : list) {
                    System.out.println(item);
                }
                
                // Modifying the list
                list.add("Item 3");
                System.out.println("After adding Item 3: " + list);
            }
        }

How does CopyOnWriteArrayList impact performance or memory usage?

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How does CopyOnWriteArrayList impact performance or memory usage?

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