private AMNodeInfo getAMNodeInfo(String amHost, int amPort, QueryIdentifier queryId) {
    Map<LlapNodeId, AMNodeInfo> amNodeInfoPerQuery = knownAppMasters.get(queryId);
    if (amNodeInfoPerQuery != null) {
      LlapNodeId amNodeId = LlapNodeId.getInstance(amHost, amPort);
      return amNodeInfoPerQuery.get(amNodeId);
    }
    return null;
  }
Responsible for communicating with various AMs.
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/AMReporter.java