private static void rowSleep() {
      if (sleepBetweenRows) {
        Threads.sleepWithoutInterrupt(rowSleepTime);
      }
    }
Custom HRegion class that instantiates {@link RegionScanner}s with configurable sleep times
between fetches of row Results and/or column family cells. Useful for emulating an instance
where the server is taking a long time to process a client's scan request
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestScannerHeartbeatMessages.java