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From "Daryn Sharp (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-2764) Fix renewal of dfs delegation tokens
Date Fri, 05 Aug 2011 15:49:27 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13080034#comment-13080034

Daryn Sharp commented on MAPREDUCE-2764:

I just re-read your comments.  There is indeed a problem with hftp, but it's not insurmountable,
and it's not incompatible with this change.

Other DFS filesystems, and h-s-ftp need only one token.  Hftp needs two tokens: http &
https.  I think this explains the non-standard behavior of hftp setting up its own token renewal

Unfortunately the existing {{FileSystem.getDelegationToken()}} only returns a single token.
 It's not unreasonable to think that filesystems, like hftp, will require multiple tokens.
 I'll probably need to add a {{FileSystem.getDelegationToken-s-}} which will return a collection
of tokens.

> Fix renewal of dfs delegation tokens
> ------------------------------------
>                 Key: MAPREDUCE-2764
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2764
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>             Fix For:
>         Attachments: MAPREDUCE-2764.patch
> The JT may have issues renewing hftp tokens which disrupt long distcp jobs.  The problem
is the JT's delegation token renewal code is built on brittle assumptions.  The token's service
field contains only the "ip:port" pair.  The renewal process assumes that the scheme must
be hdfs.  If that fails due to a {{VersionMismatchException}}, it tries https based on another
assumption that it must be hftp if it's not hdfs.  A number of other exceptions, most commonly
{{IOExceptions}}, can be generated which fouls up the renewal since it won't fallback to https.

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