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https://issues.apache.org/jira/browse/HDFS-4811?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13653262#comment-13653262
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Todd Lipcon commented on HDFS-4811:
-----------------------------------
[~andrew.wang] - would your fix you were working on to use timestamped tmp
files for checkpoints also fix this?
> race condition between 2 namenodes in standby that are trying to checkpoint
> with one another can delete or corrupt a good fsimage
> ---------------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-4811
> URL: https://issues.apache.org/jira/browse/HDFS-4811
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: ha
> Affects Versions: 3.0.0, 2.0.5-beta
> Reporter: Chris Nauroth
>
> The problem occurs under concurrent execution of the namenode running its own
> checkpoint in {{StandbyCheckpointer}} in thread 1 while also getting a
> checkpoint from a different namenode in {{GetImageServlet}} in thread 2. It
> is possible for thread 2 to finish writing the checkpoint to the directory,
> but then get suspended before it has a chance to rename it to its final
> destination as an fsimage file. Then, thread 1 wakes up and starts writing
> its own data to the checkpoint file. When thread 2 resumes, it then tries to
> rename the file that thread 1 still holds open for writing. Depending on OS,
> this either moves thread 1's incomplete checkpoint to fsimage, or it just
> outright deletes the existing good fsimage until thread 1 finishes writing
> and renames.
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