There is a potential problem with the new implementation of Thread.stop() used to fix bugs 4145906 and 4145910.
If stop() is called on Thread after start() but before it has had a chance to execute its run() method, the stop() can be ignored and the Thread continues to execute.

class SimpleThread implements Runnable {

    SimpleThread() {
        Thread thread = new Thread(this);
        thread.start();
        System.out.println("Thread.start() returned");
        thread.stop();    
        System.out.println("Thread.stop() returned");
        while (thread.isAlive()) {
            System.out.println("thread is alive");
            try {
                Thread.sleep(100);
                System.out.println("Waiting for thread to die");
            } catch(InterruptedException ie) {}
        }
    }

    public void run() {
        System.out.println("in run");
        try {
            Thread.sleep(1000);
        } catch(InterruptedException ie) {}
        System.out.println("thread finished execution");
    }

    public static void main(String args[]) {
        new SimpleThread();
    }

}

The following is the output when running JDK1.1.8 build H on an Ultra 1 Sparc (I guess it's possible that the problem may not be easily reproduced on different machines as it is critically dependent on timing):

$ /usr/local/java/jdk1.1.8/solaris/bin/java SimpleThread
Thread.start() returned
Thread.stop() returned
thread is alive
in run
Waiting for thread to die
thread is alive
Waiting for thread to die
thread is alive
Waiting for thread to die
thread is alive
Waiting for thread to die
thread is alive
Waiting for thread to die
thread is alive
Waiting for thread to die
thread is alive
Waiting for thread to die
thread is alive
Waiting for thread to die
thread is alive
Waiting for thread to die
thread is alive
thread finished execution
Waiting for thread to die

For 1.1.7B, the run() method is never executed:

$ /usr/local/java/jdk1.1.7/solaris/bin/java SimpleThread
Thread.start() returned
Thread.stop() returned

stuart.lawrence@eng 1999-03-02