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https://issues.apache.org/jira/browse/HDFS-17602?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xiaoqiao He resolved HDFS-17602.
--------------------------------
Fix Version/s: 3.5.0
Hadoop Flags: Reviewed
Resolution: Fixed
> RBF: Fix mount point with SPACE order can not find the available namespace.
> ---------------------------------------------------------------------------
>
> Key: HDFS-17602
> URL: https://issues.apache.org/jira/browse/HDFS-17602
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: router
> Reporter: Zhongkun Wu
> Assignee: Zhongkun Wu
> Priority: Critical
> Labels: pull-request-available
> Fix For: 3.5.0
>
> Attachments: image-2024-08-12-10-08-54-031.png,
> image-2024-08-12-10-08-58-271.png, image-2024-08-12-10-12-48-428.png,
> image-2024-08-12-10-14-20-580.png, image-2024-08-12-10-25-26-003.png,
> image-2024-08-12-10-25-42-863.png
>
>
> We have seventy thousand nodes in our production hadoop cluster, we use rbf
> to do namespace federation. when uses space order in rbf, and writes to the
> mount point, it fails to write and generates an empty file.
> ----
> We dug into the code and found the root cause: When create a file in rbf,
> after create rpc is invoked,the addblock rpc is invoked many times till the
> write is done. The rbf space resolver would choose an irrelevant namespace,
> and the client will write data to the wrong location
> ----
> These are the code fragments:
>
> !image-2024-08-12-10-08-58-271.png!
> In the
> MultipleDestinationMountTableResolver.java we invoke
> orderedResolver.getFirstNamespace(path, mountTableResult);
> It will then invoke this function in RouterResolver.java
> !image-2024-08-12-10-12-48-428.png!
> and now we are in
> chooseFirstNamespace function in AvailableSpaceResolver.java
> !image-2024-08-12-10-14-20-580.png!
>
> The path parameter is the destination where we want to create a file
> the loc parameter is the mount point we set
>
> this function will choose the most available namespace in all the namespace
> we have in StateStore, which is not the same as the mount point we set for
> our destination.
>
> As a result we will get a namespace irrelevant to the namespaces we set for
> the destination path
>
> !image-2024-08-12-10-25-42-863.png!
> in the log above:
> we get the namespace we don't set with our destination path, So the it will
> choose the first namespace it sees and it's not really the most available
> namespace among the namespaces we set for our destination
>
>
>
>
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