public void pingSlave() {
		for (int i = 0; i < slaveList.size(); i++) {
			SlaveWorker w = slaveList.get(i);

			if (!sendTo("check", w.ip, w.port).equals("hi")) {
				System.out.println("Slave " + w.ip + ":" + w.port
						+ " disconnected");
				// migrate work to another node

				slaveList.remove(i);
				i--;
			}
		}
	}