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https://issues.apache.org/jira/browse/HADOOP-16721?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran resolved HADOOP-16721.
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Fix Version/s: 3.3.1
Resolution: Fixed
> Improve S3A rename resilience
> -----------------------------
>
> Key: HADOOP-16721
> URL: https://issues.apache.org/jira/browse/HADOOP-16721
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.2.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Blocker
> Labels: pull-request-available
> Fix For: 3.3.1
>
> Time Spent: 3h
> Remaining Estimate: 0h
>
> h3. race condition in delete/rename overlap
> If you have multiple threads on a system doing rename operations, then one
> thread doing a delete(dest/subdir) may delete the last file under a subdir,
> and, before its listed and recreated any parent dir marker -other threads may
> conclude there's an empty dest dir and fail.
> This is most likely on an overloaded system with many threads executing
> rename operations, as with parallel copying taking place there are many
> threads to schedule and https connections to pool.
> h3. failure reporting
> the classic {[rename(source, dest)}} operation returns {{false}} on certain
> failures, which, while somewhat consistent with the posix APIs, turns out to
> be useless for identifying the cause of problems. Applications tend to have
> code which goes
> {code}
> if (!fs.rename(src, dest)) throw new IOException("rename failed and we don't
> know why");
> {code}
> This change modifies S3A FS To
> # raise FileNotFoundException if the source is missing
> # raise FileAlreadyExistsException if the destination isn't suitable for the
> source (source is a dir and the dest is one of: a file, a non-empty directory)
> It still returns false for "no-op renames" , e.g where source == dest.
> Other stores raise the same exceptions, with this change S3A moves away from
> consistency with HDFS to one where applications find out what is wrong.
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