Why singleton is not thread-safe?

2 Answers. More instances can possibly exist if you’re unlucky enough that it is accessed at the same time so both threads get past the if(INSTANCE == null) at the same time. As it forces a thread to wait if there is already another thread inside the monitor of lock , initializing the singleton.

What is an efficient way to implement a singleton pattern in Java?

1. Eager initialization: In eager initialization, the instance of Singleton Class is created at the time of class loading, this is the easiest method to create a Singleton class. By making the constructor as private you are not allowing other class to create a new instance of the class you want to create the Singleton.

How do you ensure singleton?

To create the singleton class, we need to have static member of class, private constructor and static factory method.

1. Static member: It gets memory only once because of static, itcontains the instance of the Singleton class.
2. Private constructor: It will prevent to instantiate the Singleton class from outside the class.

Why Meyers singleton is thread-safe?

The beauty of the Meyers Singleton in C++11 is that it’s automatically thread-safe. That is guaranteed by the standard: Static variables with block scope. The Meyers Singleton is a static variable with block scope, so we are done. It’s still left to rewrite the program for four threads.

How do I make singleton thread safe?

Thread Safe Singleton: A thread safe singleton in created so that singleton property is maintained even in multithreaded environment. To make a singleton class thread-safe, getInstance() method is made synchronized so that multiple threads can’t access it simultaneously.

Is singleton thread safe and how you make thread safe?

A singleton class itself is not thread safe. Multiple threads can access the singleton same time and create multiple objects, violating the singleton concept. The singleton may also return a reference to a partially initialized object.

How can we prevent Singleton from reflection using enum?

How to prevent Reflection API from breaking Singleton

1. private ReflectionSingleton() { if (instance != null ) {
2. throw new IllegalStateException( “instance already created.” ); }
3. System.out.println( “Singleton instance is being created.” ); }

How can we make Singleton class thread safe in C#?

Thread Safety Singleton using Double-Check Locking

1. public sealed class Singleton3 {
2. Singleton3() {}
3. private static readonly object lock = new object();
4. private static Singleton3 instance = null;
5. public static Singleton3 Instance {
6. get {
7. if (instance == null) {
8. lock(lock) {

Is static method thread safe C++?

Static functions are no more and no less safe than non-static ones. Being static and being thread-safe are completely orthogonal. So that said Singleton, one of the popular design pattern, is not recommended.

How can we make singleton class thread safe in spring?

To make any singleton class thread safe it is advised that make that class stateless means you should avoid defining the global variable in the singleton class.

How do I create a singleton class in thread safe?

Thread Safe Singleton in Java In general, we follow the below steps to create a singleton class: Create the private constructorto avoid any new object creation with new operator. Declare a private staticinstance of the same class. Provide a public static method that will return the singleton class instance variable.

What is singleton design pattern in Java?

Thread-Safe and a Fast Singleton Implementation – Singleton Design Pattern in java. In software engineering, the singleton pattern is a design pattern that restricts the instantiation of a class to one object. This is useful when exactly one object is needed to coordinate actions across the system.

How do I create a singleton class in Java?

In general, we follow the below steps to create a singleton class: Create the private constructorto avoid any new object creation with new operator. Declare a private staticinstance of the same class. Provide a public static method that will return the singleton class instance variable.

Is Singleton an anti-pattern?

Singleton is mostly considered an anti-Pattern, because it brings inherent complexity to the system in terms of testing. Only DI frameworks (Spring, Dagger, etc) should be allowed to create Singletons for you rather than you writing the singletons.