Doubt on thread

[Dean Jones]

The following is a question from JavaBeat mock exam.

   public class Ques02 {
public static void main(String[] args) {
Thread inactive = new Thread(new InactiveThread());
inactive.start();
Thread active = new Thread(new ActiveThread());
active.start();
}
}
class ActiveThread implements Runnable{
@Override
public void run() {
System.out.println("Active Thread");
}
}
class InactiveThread implements Runnable{
@Override
public void run() {
try {
Thread.sleep(4 * 1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Inactive Thread");
}
}
 

The choices are given as:

1. The program will output 'Active Thread' pause for a while and then print 'Inactive
Thread'.
2. The program will output 'Inactive Thread' pause for a while and then print 'Active
Thread'.
3. The program will throw a run-time exception.
4. The order of the outputs will vary upon execution.

Correct answer is given as choice 1. But I thought, it was option 4, as the order of thread execution is entirely VM dependent.

[Henry Wong]

Correct answer is given as choice 1. But I thought, it was option 4, as the order of thread execution is entirely VM dependent.

Well, yeah... but... Are there any VMs that will starve a thread for 4 whole seconds? Especially, since there are no other running threads in the system?

For the other case to happen, the inactive thread has to start first, sleep for 4 seconds, and in that time, the VM does nothing. It may be VM dependent, but have you seen a VM that does that?

Generally, when we are talking about starting threads, timeslice periods, priority behaviors, these are in the realm of milliseconds.

Henry