Double check locking is broken. Since initialized is a primitive, it may not require it to be volatile to work, however nothing prevents initialized being seen as true to the non-syncronized code before instance is initialized. EDIT: To clarify the above answer, the original question asked about using a boolean to control the double check … Read more
Double-checking locking now works in Java as well as C# (the Java memory model changed and this is one of the effects). However, you have to get it exactly right. If you mess things up even slightly, you may well end up losing the thread safety. As other answers have stated, if you’re implementing the … Read more
As quoted by @irreputable, volatile is not expensive. Even if it is expensive, consistency should be given priority over performance. There is one more clean elegant way for Lazy Singletons. public final class Singleton { private Singleton() {} public static Singleton getInstance() { return LazyHolder.INSTANCE; } private static class LazyHolder { private static final Singleton … Read more