private void updatePageSize(TerminalSize terminalSize) {
    pageSize = terminalSize.getRows() - SUMMARY_ROW_NUM - 2;
    if (pageSize < 0) {
      pageSize = 0;
    }
  }
The screen that provides a dynamic real-time view for the HBase metrics. This shows the metric
{@link Summary} and the metric {@link Record}s. The summary and the metrics are updated
periodically (3 seconds by default).
hbase-hbtop/src/main/java/org/apache/hadoop/hbase/hbtop/screen/top/TopScreenView.java