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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-2479) Backport MAPREDUCE-1568 to hadoop security branch
Date Mon, 16 May 2011 22:09:47 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2479?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13034369#comment-13034369
] 

Chris Douglas commented on MAPREDUCE-2479:
------------------------------------------

This looks like a clean backport of MAPREDUCE-1568.

The only point worth addressing in this patch is the synchronization on {{refcount}} is inconsistent.
Sometimes only the lock on {{cachedArchives}} is held, at other points only the lock on the
{{CacheStatus}} instance is held. I found no cases of inconsistent lock ordering (no deadlocks),
but it appears possible to get stale values for {{refcount}}. Since it's only incremented
while holding the lock on {{cachedArchives}}, one can only get false negatives for adding
entries to the deletion queue (i.e. one may hold onto a cached entry longer than necessary,
but one will never delete an entry in use by an initializing/running task). It's not a bad
bug, but it's probably worth fixing.

+1 otherwise, particularly with the pending work in MAPREDUCE-2495 and MAPREDUCE-2494.

> Backport MAPREDUCE-1568 to hadoop security branch
> -------------------------------------------------
>
>                 Key: MAPREDUCE-2479
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2479
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: tasktracker
>    Affects Versions: 0.20.204.0
>            Reporter: Robert Joseph Evans
>            Assignee: Robert Joseph Evans
>             Fix For: 0.20.205.0
>
>         Attachments: MAPREDUCE-2479-v1.patch
>
>


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