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https://issues.apache.org/jira/browse/HDFS-11817?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16020252#comment-16020252
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Kihwal Lee commented on HDFS-11817:
-----------------------------------

In trunk, there already is a logic to weed out null StorageInfo before putting 
one to the expected locations. This was done by as part of HDFS-9040. It too 
had TestRetryCacheWithHA failed, so it was also fixed as part of HDFS-9040, 
although I believe my fix is better. As it is a EC-related change, the JIRA 
cannot be applied to branch-2.   I will back-port the relevant portion in my 
patch, so that trunk and branch-2/2.8 stays more in sync.  The trunk version of 
my patch will contain the test case (HDFS-9040 did not add a new test case for 
this) and the lease manager fix.

> A faulty node can cause a lease leak and NPE on accessing data
> --------------------------------------------------------------
>
>                 Key: HDFS-11817
>                 URL: https://issues.apache.org/jira/browse/HDFS-11817
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.8.0
>            Reporter: Kihwal Lee
>            Assignee: Kihwal Lee
>            Priority: Critical
>         Attachments: HDFS-11817.branch-2.patch, hdfs-11817_supplement.txt
>
>
> When the namenode performs a lease recovery for a failed write, the 
> {{commitBlockSynchronization()}} will fail, if none of the new target has 
> sent a received-IBR.  At this point, the data is inaccessible, as the 
> namenode will throw a {{NullPointerException}} upon {{getBlockLocations()}}.
> The lease recovery will be retried in about an hour by the namenode. If the 
> nodes are faulty (usually when there is only one new target), they may not 
> block report until this point. If this happens, lease recovery throws an 
> {{AlreadyBeingCreatedException}}, which causes LeaseManager to simply remove 
> the lease without  finalizing the inode.  
> This results in an inconsistent lease state. The inode stays 
> under-construction, but no more lease recovery is attempted. A manual lease 
> recovery is also not allowed. 



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