private void addToQueue(KeyValueReader kvReader) throws IOException {
    if (kvReader.next()) {
      kvReaderStandardObjMap.remove(kvReader);
      pQueue.add(kvReader);
    }
  }
Add KeyValueReader to queue if it has more key-value

@param kvReader
@throws IOException
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/tools/KeyValueInputMerger.java