SINGLETON PATTERNFall of double check

by Talha Ocakçı

GOAL of SINGLETON PATTERN

Using the same instance throughout the application. When we want to

● Use huge objects without-recreating● Centralizing a process

HOW TO CREATEThe simplest form

1 - Define a static instance of itself inside the class, initialize it as null

2- Make the constructor private

3- Define a getInstance method, call the constructor if the inner instance is null

Simplest implementation

Race condition in multithread

Thread 1Thread 2

Race condition in multithread

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Thread 2

Race condition in multithread

Thread 1

Thread 2

Race condition in multithread

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Thread 2

Java Memory Management Problem

Object creation with new keyword has several non-atomic hidden operations.

Object creation

1- Allocate memory

2- Use stack space for related address

3- Initialize object

4- Flush the values to common memory

What is flushing?

Flushing means, writing a modified object’s state to common memory area

volatile object creation

1- Allocate memory

2- Use stack space for related address

3- Initialize object

4- Flush the values to common memory

volatile, makes the object modification an atomic process

Latest version

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