public void returnUmbilicalUgi(String appTokenIdentifier, UserGroupInformation ugi) {
      BlockingQueue<UserGroupInformation> ugiQueue = ugiPool.getIfPresent(appTokenIdentifier);
      // Entry could have been removed due to expiry. Check before returning back to queue
      if (ugiQueue != null) {
        ugiQueue.offer(ugi);
      }
    }
Return UGI back to pool

@param appTokenIdentifier AM identifier
@param ugi
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/ContainerRunnerImpl.java