primarily two reasons:
1. There is no recurring communication channel between NM and AM.
2. Application must act on single source of truth, which is RM.
On Sun, Nov 27, 2011 at 9:01 PM, Praveen Sripati
> According to
> >Completed containers: Once an ApplicationMaster triggers a launch an
> allocated container, it will receive an update from the ResourceManager
> when the container completes. The ApplicationMaster can look into the
> status of the completed container and take appropriate actions such as
> re-trying a particular sub-task in case of a failure.
> My understanding is NM sends the completed status of the containers to the
> RM and the RM in turn sends the status to AM. Why can't the NM send the
> status of the completed containers to the AM directly? The NM will anyway
> know which AM has requested for launching the containers.