protected KeyValueHeap newKVHeap(List<? extends KeyValueScanner> scanners,
    CellComparator comparator) throws IOException {
    return new KeyValueHeap(scanners, comparator);
  }
Seek the specified scanners with the given key
@param isLazy         true if using lazy seek
@param isParallelSeek true if using parallel seek
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreScanner.java