private void writeStringToFile(String s, String fileName) {
    try {
      BufferedWriter out = new BufferedWriter(new FileWriter(fileName));
      out.write(s);
      out.close();
    } catch (IOException e) {
      LOG.error("Error writing to: " + fileName, e);
    }
  }
Generates a list of random port numbers in the sorted order. A sorted order makes sense if we
ever want to refer to these servers by their index in the returned array, e.g. server #0, #1,
etc.
hbase-diagnostics/src/test/java/org/apache/hadoop/hbase/util/ProcessBasedLocalHBaseCluster.java