Now, RM track application log aggregation status in RMApp and the status change is triggered by NM heartbeat with log aggregation report. For each node's log aggregation status change from in-progress (NOT_START,RUNNING,RUNNING_WITH_FAILURE) to final status (SUCCEEDED,FAILED, TIMEOUT), it trigger an aggregation for log aggregation status: updateLogAggregationStatus(). The whole progress is log less and we cannot trace the log aggregation problem (delay of log aggregation, etc.) from RM (or NM) log. We should add more log here.