code: @Override
      public void instanceIsActive() throws AtlasException {
          LOG.info("Reacting to active: initializing index");
          try {
              initialize();
          } catch (RepositoryException | IndexException e) {
              throw new AtlasException("Error in reacting to active on initialization", e);
          }
      }
docs: Initialize global indices for Titan graph on server activation.
  
  Since the indices are shared state, we need to do this only from an active instance.