try {
            serverSocket = new ServerSocket(PORT);
            System.out.println("Server running. Waiting for connection");
                while (running) {
             Socket clientSocket = serverSocket.accept();
                     pool.execute(new ServerThread(clientSocket));
                     clientCounter.getAndIncrement();
             }
            pool.shutdown();
            } catch (IOException e) {
            e.printStackTrace();
        }