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https://issues.apache.org/jira/browse/HDFS-4688?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13629746#comment-13629746
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Fengdong Yu commented on HDFS-4688:
-----------------------------------
Hi Harsh,
I do misunderstood. the attached program illustrated everything now.
so I attached a minor patch for this issue.
> DFSClient should not allow multiple concurrent creates for the same file
> ------------------------------------------------------------------------
>
> Key: HDFS-4688
> URL: https://issues.apache.org/jira/browse/HDFS-4688
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 3.0.0, 2.0.3-alpha
> Reporter: Andrew Wang
> Assignee: Andrew Wang
> Attachments: HDFS-4688.txt, TestBadFileMaker.java
>
>
> Credit to Harsh for tracing down most of this.
> If a DFSClient does create with overwrite multiple times on the same file, we
> can get into bad states. The exact failure mode depends on the state of the
> file, but at the least one DFSOutputStream will "win" over the others,
> leading to data loss in the sense that data written to the other
> DFSOutputStreams will be lost. While this is perhaps okay because of
> overwrite semantics, we've also seen other cases where the DFSClient loops
> indefinitely on close and blocks get marked as corrupt. This is not okay.
> One fix for this is adding some locking to DFSClient which prevents a user
> from opening multiple concurrent output streams to the same path.
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