@Override
  /**
   * This method is protected under {@link HStore#lock} read lock. <br/>
   * Scanners are ordered from 0 (oldest) to newest in increasing order.
   */
  public List<KeyValueScanner> getScanners(long readPt) throws IOException {
    List<KeyValueScanner> list = new ArrayList<>();
    addToScanners(getActive(), readPt, list);
    addToScanners(getSnapshotSegments(), readPt, list);
    return list;
  }
Creates a snapshot of the current memstore. Snapshot must be cleared by call to
{@link #clearSnapshot(long)}
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/DefaultMemStore.java