regarding this output format, in HDFS, couldn't you have different NC's with the exact same file?  You use a lock which prevents threads within this NC from using the same time but different NCs could still get the same time.  

You could incorporate the hostname via a locked, static allocation block which calls to `DriverUtils.getIP("localhost");`.  In other words, incorporate the hostname into the filename.  Then the file will be guaranteed unique.