public DFSMaster(JobTracker tracker) {
		slaveList = new HashMap<Integer, String>();
		jobToSlaveFile = new HashMap<Integer, HashMap<Integer, HashSet<FileSplit>>>();
		dfsNode = new PriorityQueue<Pair>();
		commModule = new CommModule();
		this.tracker = tracker;
		jobTaskCount = new HashMap<Integer, Integer>();
	}