public void kickOff(File f) {
		try {
			String line; 
			BufferedReader in = new BufferedReader(new FileReader(f));

			while ((line = in.readLine()) != null) {
				int[] trans = StringToInts(line);
				queue.put(new Transaction(trans));
			}
			in.close();
			// file reading ends, now send end signals to workers.
			// one per thread.
			for (int i = 0; i < numThreads; i++)
				queue.put(nullTrans);

		} catch (IOException e) {
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
		}
	}