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https://issues.apache.org/jira/browse/HDFS-1332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13034436#comment-13034436
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Tsz Wo (Nicholas), SZE commented on HDFS-1332:
----------------------------------------------
- Just found one problem: In the two {{chooseRandom(..)}} methods (line 333-363
and line 378-422), if the first {{FSNamesystem.LOG.isDebugEnabled()}} return
false and the second {{FSNamesystem.LOG.isDebugEnabled()}} returns true, we
will have a {{NullPointerException}} since {{builder}} is null. We should
check null for the second if-statement.
- There are repeated "Not able to place enough replicas" in the log message. I
think we might have {{new NotEnoughReplicasException(detail)}} and then use
{{"\n" + e}} instead of {{"\n" + e.getMessage()}} in {{LOG.warn(..)}}. Then,
the log will become something like
{noformat}
2011-05-16 16:37:04,230 WARN namenode.FSNamesystem
(BlockPlacementPolicyDefault.java:chooseTarget(212)) - Not able to place enough
replicas, still in need of 1 to reach 2
NotEnoughReplicasException: [127.0.0.1:49864: Node
/default-rack/127.0.0.1:49864 is not chosen because the node is (being)
decommissioned ]
{noformat}
> When unable to place replicas, BlockPlacementPolicy should log reasons nodes
> were excluded
> ------------------------------------------------------------------------------------------
>
> Key: HDFS-1332
> URL: https://issues.apache.org/jira/browse/HDFS-1332
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: name-node
> Reporter: Todd Lipcon
> Assignee: Ted Yu
> Priority: Minor
> Labels: newbie
> Fix For: 0.23.0
>
> Attachments: HDFS-1332-concise.patch
>
>
> Whenever the block placement policy determines that a node is not a "good
> target" it could add the reason for exclusion to a list, and then when we log
> "Not able to place enough replicas" we could say why each node was refused.
> This would help new users who are having issues on pseudo-distributed (eg
> because their data dir is on /tmp and /tmp is full). Right now it's very
> difficult to figure out the issue.
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