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https://issues.apache.org/jira/browse/YARN-4497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15095389#comment-15095389
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Jun Gong commented on YARN-4497:
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[~jianhe] Thanks for review and comments.
{quote}
for the patch, I think making below change in RMAppImpl#recover may be enough ?
{quote}
There might be some problems:
1. *appState.attempts.keySet()* is not sorted by attempt ID, however we need
recover them by order because we use *currentAttempt* to get AMBlacklist and we
calle *getNumFailedAppAttempts()* in *createNewAttempt()* .
2. We need update *nextAttemptId* after recovering attempts.
3. We need to deal with the case 2 in previous comment: attempt's final state
is missed(fail to store its final state), otherwise it will cause RM to
relaunch this attempt: it will be in *LAUNCEHD* state after recover, and will
time out(the attempt has already failed), then RM will relaunch it.
> 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
> Priority: Critical
> Attachments: YARN-4497.01.patch
>
>
> 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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