A kernel programmer's singleton

Singleton.java

import java.util.concurrent.locks.ReentrantLock;

public class Singleton implements Runnable {
	private static Singleton INSTANCE;
	private static ReentrantLock LOCK = new ReentrantLock();
	
	private Singleton() { }
	
	public Singleton getInstance() {
		new Thread(this).run();
		
		while(INSTANCE == null) {
			Thread.yield();
		}
		return INSTANCE;
	}

	@Override
	public void run() {
		LOCK.lock();
		INSTANCE = new Singleton();		
	}
}

Doesn't that mean that every call of getInstance() creates a new INSTANCE object (therefore not a singleton)?

No, because of lock.

Wouldn't every call to getInstance create a new thread, but after the first call, each subsequent thread would just block indefinitely on the lock. So you would leak threads.

Threads are free, right?

I wrote this to be on par with http://xkcd.com/1185/