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https://issues.apache.org/jira/browse/HDFS-12942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16298948#comment-16298948
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Virajith Jalaparti commented on HDFS-12942:
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Hi [~ajayydv], thanks for posting the patch to fix this. A few comments:
# Is it necessary to call {{processBlockInvalidation}} in
{{cleanupNewReplica}}? The {{newReplicaInfo}} passed in isn't used for reading
as it is just temporary for the block move. This call will invalidate any
references to the original replica which was used to create the
newReplicaInfo}}. So, I think this call is not required.
# The rest of the code in {{cleanupNewReplica}} is same as the deletion logic
in {{removeOldReplica}}. If this method is being added, it would be useful to
refactor {{removeOldReplica}} and call {{cleanupNewReplica}} instead of having
the same logic in two places. I would rename {{cleanupNewReplica}} to say
{{cleanupReplica}} when this refactoring is done.
# I think a method name like {{FsDatasetImpl#copyReplicaToVolume}} instead of
{{FsDatasetImpl#createNewReplicaObj}} would make it clearer what that method is
doing. I would also clarify in the javadoc that the method creates a
{{TEMPORARY}} replica in the volume passed in.
# A javadoc for {{TestFsDatasetImpl#createNewReplicaObj}} would be useful.
# {{"Generation Stamp should be monotonically increased. That assumption is
violated here."}} I think the latter part of the message ({{"That assumption is
violated here"}}) isn't required.
> Synchronization issue in FSDataSetImpl#moveBlock
> ------------------------------------------------
>
> Key: HDFS-12942
> URL: https://issues.apache.org/jira/browse/HDFS-12942
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Ajay Kumar
> Assignee: Ajay Kumar
> Attachments: HDFS-12942.001.patch
>
>
> FSDataSetImpl#moveBlock works in following following 3 steps:
> # first creates a new replicaInfo object
> # calls finalizeReplica to finalize it.
> # Calls removeOldReplica to remove oldReplica.
> A client can potentially append to the old replica between step 1 and 2.
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