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From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-2764) Fix renewal of dfs delegation tokens
Date Wed, 31 Aug 2011 15:54:10 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13094633#comment-13094633
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Owen O'Malley commented on MAPREDUCE-2764:
------------------------------------------

Daryn,

Your patch doesn't compile because you are using @Override on the cancel/renew token methods
in DistributedFileSystem. I assume you forgot to include FileSystem in your patch. When delegation
tokens were added, there was agreement that adding those methods to FileSystem wasn't appropriate.
We can re-open that discussion, but it needs to be discussed more widely.

I also assume that the change to fixFontPaths is accidental.

I'm glad to see the move to use methods on Token, I think that is appropriate. I also like
the isRenewable method, although it also controls whether it is cancelable so probably needs
a better name like isManaged.

Please don't remove InterruptedException from APIs. At some point we'll fix RPC to properly
throw InterruptedException when it is waiting.

We've been burned badly before by the idiom of using static blocks to register types. The
ServiceLookup is much better.

Adding a transient field that is lost when going over RPC is problematic from a maintenance
point of view. It also doesn't feel justified, just so that we can continue to intermingle
HFTP delegation tokens with HFTP delegation tokens. It seems to make much more sense to separate
the HFTP tokens out and use the service field to refer to the HFTP address, in the way it
was intended to be used.

I'm still looking through the patch, but wanted to provide the high level feedback.

Changing the semantics of JobClient.addAll isn't ok.

> 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: 0.20.205.0
>
>         Attachments: MAPREDUCE-2764-2.patch, MAPREDUCE-2764.patch, delegation.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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