public DataSet showTopics() {
    acquireReadLock();
    try {
      return new TopicTableResp(
          new TSStatus(TSStatusCode.SUCCESS_STATUS.getStatusCode()),
          StreamSupport.stream(topicMetaKeeper.getAllTopicMeta().spliterator(), false)
              .collect(Collectors.toList()));
    } finally {
      releaseReadLock();
    }
  }
Caller should ensure that the method is called in the lock {@link #acquireWriteLock}.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/persistence/subscription/SubscriptionInfo.java