Java Multithreading - Thread Pools

package demo;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

class Processor implements Runnable{
 
 private int id;
 
 public Processor(int id) {
  this.id = id;
 }
 
 @Override
 public void run() {
  
  System.out.println("Starting Thread: " + id);
  
  //simulate some work which can take some time
  try {
   Thread.sleep(2000); 
  }catch(InterruptedException e) {
   //e.printStackTrace();
  }
  
  System.out.println("Finished Thread: " + id);
  
 }
 
}

public class App {

 public static void main(String[] args) {
  
  //we will use an executor service to have multiple threads work on multiple tasks assigned to them
  //here, are setting the Thread Pool size to 2. So, there will be 2 workers or threads which will work on the tasks given.
  //when one of the tasks is complete, it will keep taking the other tasks until they are complete
  ExecutorService executorService = Executors.newFixedThreadPool(5);
  
  //submit 10 tasks
  for(int i=0; i<10; i++) {
   executorService.submit(new Processor(i));
  }
  
  //disable new tasks from being submitted
  executorService.shutdown();
  
  System.out.println("All tasks submitted.\n");
  
  try {
   
   int time = 2;
   
   //wait a while for existing tasks to terminate
   //executorService.awaitTermination(time, TimeUnit.SECONDS);
   
   //cancel currently executing tasks
   
   //awaitTermination blocks until all tasks have completed execution after a shutdownrequest, or the timeout occurs, or the current thread is interrupted, whichever happens first.
   //returns true if this executor terminated and false if the timeout elapsed before termination
   if (executorService.awaitTermination(time, TimeUnit.SECONDS))
    System.out.println("All tasks completed.");
   else {
    //attempts to stop all actively executing tasks, halts theprocessing of waiting tasks, and returns a list of the tasksthat were awaiting execution. 
    executorService.shutdownNow();
    System.out.println("Shutting down pending tasks since they did not complete within " + time + " " + TimeUnit.SECONDS);
   }
   
  } catch (InterruptedException e) {
   e.printStackTrace();
  }
  
 }
 
}