[
https://issues.apache.org/jira/browse/HDFS-11817?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16010646#comment-16010646
]
Kihwal Lee commented on HDFS-11817:
-----------------------------------
There are two possible immediate fixes that can be implemented.
- Allow {{commitBlockSynchronization()}} to complete even if a received-IBR is
not received (I.e. last block not in COMPLETE state). This is equivalent of
allowing closing without the last block being COMPETE.
- Do not allow {{LeaseManager}} to blindly remove the lease on a lease recovery
failure and leave the inode in under-construction state.
They are all simple changes that will prevent the issues from happening.
However, I haven't been able to root cause how and where NPE is happening. It
is from calling {{getBlockLocations()}}, but so far I have not been able to
reproduce it. I will find other means to RC it.
> 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
>
> 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.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
