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