private void removeFromCache(String path, String host) {
    instanceCacheLock.lock();
    try {
      pathToInstanceCache.remove(path);
      nodeToInstanceCache.remove(host);
    } finally {
      instanceCacheLock.unlock();
    }
    LOG.debug("Removed path={}, host={} from cache."
            + " pathToInstanceCache:size={}, nodeToInstanceCache:size={}",
        path, host, pathToInstanceCache.size(), nodeToInstanceCache.size());
  }
Get the ensemble server addresses from the configuration. The format is: host1:port,
host2:port..

@param conf configuration
llap-client/src/java/org/apache/hadoop/hive/registry/impl/ZkRegistryBase.java