public Result append(Append append, long nonceGroup, long nonce) throws IOException {
    return TraceUtil.trace(() -> {
      checkReadOnly();
      checkResources();
      startRegionOperation(Operation.APPEND);
      try {
        // All edits for the given row (across all column families) must happen atomically.
        return mutate(append, true, nonceGroup, nonce).getResult();
      } finally {
        closeRegionOperation(Operation.APPEND);
      }
    }, () -> createRegionSpan("Region.append"));
  }
Returns statistics about the current load of the region
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java