void removeTaskAttempt(TezTaskAttemptID attemptId) {
      Boolean oldVal = tasks.remove(attemptId);
      if (oldVal == null) {
        throw new RuntimeException(attemptId + " was not registered and couldn't be removed");
      }
    }
Responsible for communicating with various AMs.
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/AMReporter.java