public Iterable<TopicMeta> getAllTopicMeta() {
    acquireReadLock();
    try {
      return topicMetaKeeper.getAllTopicMeta();
    } 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