[jira] [Commented] (HADOOP-15086) NativeAzureFileSystem.rename is not atomic

["Cheng Lian (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-15086?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16275422#comment-16275422 ] 

Cheng Lian commented on HADOOP-15086:
-------------------------------------

To be more specific, when multiple threads rename files to the same target path, more than 1 *but not all* threads can succeed. It's because check and copy file in {{NativeAzureFileSystem#rename()}} is not atomic.

The problem here is that it's unclear what the expected semantics of {{NativeAzureFileSystem#rename()}} is:

- If the semantics is "error if the destination file already exists", then only 1 thread can succeed.
- If the semantics is "overwrite if the destination file already exists", then all threads should succeed.

> NativeAzureFileSystem.rename is not atomic
> ------------------------------------------
>
>                 Key: HADOOP-15086
>                 URL: https://issues.apache.org/jira/browse/HADOOP-15086
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/azure
>    Affects Versions: 2.7.3
>            Reporter: Shixiong Zhu
>         Attachments: RenameReproducer.java
>
>
> When multiple threads rename files to the same target path, more than 1 threads can succeed. It's because check and copy file in `rename` is not atomic.
> I would expect it's atomic just like HDFS.



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