private void discardUncachedBuffers(List<MemoryBuffer> list) {
    for (MemoryBuffer buffer : list) {
      bufferManager.getAllocator().deallocate(buffer);
    }
  }
Unlike the other overload of processOneSlice, doesn't cache data.
llap-server/src/java/org/apache/hadoop/hive/llap/io/encoded/SerDeEncodedDataReader.java