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https://issues.apache.org/jira/browse/YARN-1366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14001385#comment-14001385
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Rohith commented on YARN-1366:
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Thats good point to discuss and take descision should RESYNC to be handle in 
new API or use exiting method.

CMIIW, My point of view is that 
1. Separate API for resync, eventually differentiate for RM registered vs RM 
launched but not register. RM treats both applications as same in terms of APP 
state transition.Only we can avoid updating some of the data 
structure(trackingURI) from new API.
2. bq.Are there any other advantage on the RM side by having this information 
come together in 1 "atomic" operation?
   I see , RM does not have any specific advantage of receiving pending request 
at one shot, infact schedulers can server request faster. OTOH , AM's can 
reduce responsibility of resending request in batch(for next heartbeats) . 
Batch  processing would require to define fraction that which each set of 
request sent to RM.
3.For the case where AM last heart beat has been sent to RM, and RM restarted 
before finishApplicationMaster() called. Does ApplicationMaterServer send 
resync.?

> ApplicationMasterService should Resync with the AM upon allocate call after 
> restart
> -----------------------------------------------------------------------------------
>
>                 Key: YARN-1366
>                 URL: https://issues.apache.org/jira/browse/YARN-1366
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: resourcemanager
>            Reporter: Bikas Saha
>            Assignee: Rohith
>         Attachments: YARN-1366.1.patch, YARN-1366.2.patch, YARN-1366.patch, 
> YARN-1366.prototype.patch, YARN-1366.prototype.patch
>
>
> 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.



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