@Override
    public List<OrcSplit> call() throws IOException {
      if (ugi == null) {
        return callInternal();
      }
      try {
        return ugi.doAs(new PrivilegedExceptionAction<List<OrcSplit>>() {
          @Override
          public List<OrcSplit> run() throws Exception {
            return callInternal();
          }
        });
      } catch (InterruptedException e) {
        throw new IOException(e);
      }
    }
Divide the adjacent stripes in the file into input splits based on the
block size and the configured minimum and maximum sizes.
ql/src/java/org/apache/hadoop/hive/ql/io/orc/OrcInputFormat.java