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Posted to hdfs-dev@hadoop.apache.org by "Chris Nauroth (JIRA)" <ji...@apache.org> on 2013/05/10 00:45:16 UTC
[jira] [Resolved] (HDFS-4811) race condition between 2 namenodes in
standby that are trying to checkpoint with one another can delete or
corrupt a good fsimage
[ https://issues.apache.org/jira/browse/HDFS-4811?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Chris Nauroth resolved HDFS-4811.
---------------------------------
Resolution: Duplicate
I've reassigned HDFS-3519 to myself, and I'm resolving HDFS-4811 as duplicate. Thanks, Todd and Andrew.
> 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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