private void addToQueue(KeyValuesReader kvsReadr) throws IOException{
    if(kvsReadr.next()){
      pQueue.add(kvsReadr);
    }
  }
Add KeyValuesReader to queue if it has more key-values
@param kvsReadr
@throws IOException
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/tools/KeyValuesInputMerger.java