boolean isRequestedHostPresent(TaskInfo request) {
    return (request.requestedHosts != null && request.requestedHosts.length > 0);
  }
The difference between this and getTotalResources() is that this only gives currently free
resource instances, while the other lists all the instances that may become available in a
while.
llap-tez/src/java/org/apache/hadoop/hive/llap/tezplugins/LlapTaskSchedulerService.java