The ApplicationMasterService currently sends a resync response to which the AM responds by shutting down. The AM behavior is expected to change to calling resyncing with the RM. Resync means resetting the allocate RPC sequence number to 0 and the AM should send its entire outstanding request to the RM. Note that if the AM is making its first allocate call to the RM then things should proceed like normal without needing a resync. The RM will return all containers that have completed since the RM last synced with the AM. Some container completions may be reported more than once.