public class MailSystem implements SelfTunable {
 
  private static final Integer MAX_NUM_OF_WORKERS = 1000;
  private static final Integer INITIAL_NUM_OF_WORKERS = 10;
  private Integer NUM_OF_WORKERS = INITIAL_NUM_OF_WORKERS;
  
  public Boolean send(String message){
    // as you have more than 1k messages to sends add 2 more workers
    // if you have less than 1k messages reduce 2 workers
    // initial number of workers is 10; If you keep adding workers stop when you have 1k workers
    // this system is similar to AutoScaling group concepts. Most of times you dont need do this inernaly thats to ASGs :D
  }
  
}