private static String getIp16(final String ip) {
        final String[] segments = ip.split("\\.");
        final StringBuilder buf = StringBuilderHelper.get();
        for (final String s : segments) {
            final String hex = Integer.toHexString(Integer.parseInt(s));
            if (hex.length() == 1) {
                buf.append('0');
            }
            buf.append(hex);
        }
        return buf.toString();
    }
Gets current pid, max pid 32 bit systems 32768, for 64 bit 4194304
http://unix.stackexchange.com/questions/16883/what-is-the-maximum-value-of-the-pid-of-a-process
http://stackoverflow.com/questions/35842/how-can-a-java-program-get-its-own-process-id
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/util/UniqueIdUtil.java