Oracle Java 7 update 5 UUID race condition

UUIDTest.java

import java.util.List;
import java.util.concurrent.ConcurrentSkipListSet;
import java.util.LinkedList;
import java.util.Set;
import java.util.UUID;

class UUIDGenThread extends Thread {

    private final Set<UUID> set;
    private final int numUUIDS;

    public UUIDGenThread(Set<UUID> set, int numUUIDS) {
        this.set = set;
        this.numUUIDS = numUUIDS;
    }

    public void run() {
        for(int i=0; i<numUUIDS; ++i) {
            UUID uuid = UUID.randomUUID();
            if(!set.add(uuid)) System.out.println("Collision: " + uuid);
        }
    }

}


public class UUIDTest {

    public static void main(String[] args) throws InterruptedException {

        Set<UUID> set = new ConcurrentSkipListSet<UUID>();

        List<Thread> threads = new LinkedList<Thread>();
        for(int i=0; i<128; ++i) {
            threads.add(new UUIDGenThread(set, 100000));
        }

        for(Thread t: threads) t.start();
        for(Thread t: threads) t.join();

        System.out.println("Set size: " + set.size());
    }
}