(thread) A thread can be cloned and that breaks getId() contract

FULL PRODUCT VERSION :
java version "1.6.0-ea"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-ea-b33)
Java HotSpot(TM) Client VM (build 1.6.0-ea-b33, mixed mode, sharing)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
It's possible to clone a thread by creating a subclass of Thread
that override clone(). A thread and its clone share the same thread id.

I think that Thread.clone() must be ovverride to :
solution 1: prohibit clone() by returns a CloneNotSupported exception
solution 2 : call nextThreadID() to update the thread id.

The solution 2 avoid to breaks code that already clone threads.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create a subclass of thread
Make it Cloneable
Override clone()
Create a thread, clone it
start the two
they have the same thread id (getId())

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
8567361 5 7
9584176 5 8
ACTUAL -
8567361 5 7
9584176 5 7


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class CloneThreadTest extends java.lang.Thread implements Cloneable {
  @Override
  public CloneThreadTest clone() throws CloneNotSupportedException {
    return (CloneThreadTest)super.clone();
  }
  @Override
  public void run(){
    for(;;) {
      System.out.println(System.identityHashCode(this)+" "+getPriority()+" "+getId());
      try {
        Thread.sleep(100);
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
  }
  public static void main(String[] args) throws CloneNotSupportedException, InterruptedException{
      CloneThreadTest t = new CloneThreadTest();
      Thread t2=t.clone();
      
      t.start();
      t2.start();
  }
}
---------- END SOURCE ----------
###@###.### 2005-04-29 20:40:25 GMT