private void handleLs(String[] cmdLine){
        if(0 == workersMap.size())
            System.out.println("no worker in system");
        else{
            for(int i : workersMap.keySet()){
                //System.out.println("id "+i+"status "+workerStatusMap.get(i));
                if(workerStatusMap.get(i) == -1)
                    System.out.println("worker ID: "+i+"  IP Address: "+workersMap.get(i).getInetAddress()+" FAILED");
                else
                    System.out.println("worker ID: "+i+"  IP Address: "+workersMap.get(i).getInetAddress()+" ALIVE");
            }
        }
    }