private static long memusagerss() {
    long rss = -1;
    try {
      Reader fr = new FileReader("/proc/self/status");
      LineNumberReader lnr = new LineNumberReader(fr);
      String line;
      while ((line = lnr.readLine()) != null) {
        int idx = line.indexOf(':');
        if (idx < 0) continue;
        String name = line.substring(0, idx);
        idx++;
        while (idx < line.length() && Character.isWhitespace(line.charAt(idx))) idx++;
        String value = line.substring(idx, line.length());
        if (name.equals("VmRSS")) {
          rss = Utility.atoix(value);
          break;
        }
      }
      fr.close();
    } catch (Exception e) {
    }
    return rss;
  }