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https://issues.apache.org/jira/browse/YARN-4497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15069470#comment-15069470
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Rohith Sharma K S commented on YARN-4497:
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Currently, If any errors happened while storing into RMstateStore then 
RMStatestore is FENCED. So no more attempts are stored in state-store. And the 
RMStatState store state machine has transition is only from {{ACTIVE to 
FENCED}} but there is No {{FENCED to ACTIVE}}. 

If I am missing anything in flow, could you explain elaborately? 

> RM might fail to restart when recovering apps whose attempts are missing
> ------------------------------------------------------------------------
>
>                 Key: YARN-4497
>                 URL: https://issues.apache.org/jira/browse/YARN-4497
>             Project: Hadoop YARN
>          Issue Type: Bug
>            Reporter: Jun Gong
>            Assignee: Jun Gong
>
> Find following problem when discussing in YARN-3480.
> If RM fails to store some attempts in RMStateStore, there will be missing 
> attempts in RMStateStore, for the case storing attempt1, attempt2 and 
> attempt3, RM successfully stored attempt1 and attempt3, but failed to store 
> attempt2. When RM restarts, in *RMAppImpl#recover*, we recover attempts one 
> by one, for this case, we will recover attmept1, then attempt2. When 
> recovering attempt2, we call  
> *((RMAppAttemptImpl)this.currentAttempt).recover(state)*, it will first find 
> its ApplicationAttemptStateData, but it could not find it, an error will come 
> at *assert attemptState != null*(*RMAppAttemptImpl#recover*, line 880).



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