@Override
  public LlapServiceInstanceSet getInstances(
      String component, long clusterReadyTimeoutMs) throws IOException {
    PathChildrenCache instancesCache = ensureInstancesCache(clusterReadyTimeoutMs);

    // lazily create instances
    if (instances == null) {
      this.instances = new DynamicServiceInstanceSet(instancesCache, this, encoder);
    }
    return instances;
  }
A dynamically changing instance in an Llap Service. Can become inactive if failing or can be
blacklisted (set to 0 capacity) if too slow (See: BlacklistingLlapMetricsListener).
llap-client/src/java/org/apache/hadoop/hive/llap/registry/impl/LlapZookeeperRegistryImpl.java