[jira] [Commented] (YARN-1146) RM DTSM and RMStateStore mismanage sequence number

["Daryn Sharp (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-1146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13757983#comment-13757983 ] 

Daryn Sharp commented on YARN-1146:
-----------------------------------

Note that bug #2 will not self-correct if the following sequence occurs:
# Issue token 1, 2, 3, 4 (seq=4)
# Renew token 2 (seq=2)
# Cancel token 3, 4 (seq=2)
# Stop RM
# Start RM (seq=2) and will issue token 3 and 4 again

The issue is _probably_ benign given the current implementation, but is a bug if anything relies on sequence number.
                
> RM DTSM and RMStateStore mismanage sequence number
> --------------------------------------------------
>
>                 Key: YARN-1146
>                 URL: https://issues.apache.org/jira/browse/YARN-1146
>             Project: Hadoop YARN
>          Issue Type: Bug
>    Affects Versions: 2.0.0-alpha
>            Reporter: Daryn Sharp
>
> {{RMDelegationTokenSecretManager}} implements {{storeNewToken}} and {{updateStoredToken}} (renew) to pass the token and its sequence number to {{RMStateStore#storeRMDelegationTokenAndSequenceNumber}}.
> There are two problems:
> # The assumption is that new tokens will be synchronously stored in-order.  With an async secret manager this may not hold true and the state's sequence number may be incorrect.
> # A token renewal will reset the state's sequence number to _that token's_ sequence number.
> Bug #2 is generally masked.  Creating a new token (with the first caveat) will bump the state's sequence number back up.  Restoring the dtsm will first set the state's stored sequence number, then re-add all the tokens which will update the sequence number if the token's sequence number is greater than the dtsm's current sequence number.

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