@Override
  protected String getZkPathUser(Configuration conf) {
    // External LLAP clients would need to set LLAP_ZK_REGISTRY_USER to the LLAP daemon user (hive),
    // rather than relying on LlapRegistryService.currentUser().
    return HiveConf.getVar(conf, ConfVars.LLAP_ZK_REGISTRY_USER, LlapRegistryService.currentUser());
  }
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