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https://issues.apache.org/jira/browse/HDFS-4839?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13848747#comment-13848747
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Colin Patrick McCabe commented on HDFS-4839:
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Hi [[email protected]]. I agree with you that we can't change the behavior
of {{FileSystem#mkdir}}, in {{LocalFileSystem}} or any other subclass. I was
not proposing that. Sorry if it was unclear. I was proposing that we use a
version of mkdirs which provides error information internally in the HDFS
{{NameNode}}, {{DataNode}}, etc. Currently, we get very little information
about why something failed, and that makes debugging challenging.
For example, if the NameNode's {{Storage#clearDirectory}} fails with "Cannot
create directory", what can we tell users now? Not very much. It could be
permissions, an I/O error, disk full, or something else. "I don't know, could
be anything" is not something users like to hear on a mailing list.
bq. If this can be done in Java7 then its not worth doing here, unless a goal
is to backport behaviour to java6 runtimes.
Well, as of now (December 2013), all versions of Hadoop must build on Java6.
It is a supported platform. In the past, we've added JNI or other workarounds
to overcome deficiencies in Java6. I don't see why this time is any different,
especially given the small amount of code we're talking about here.
> add NativeIO#mkdirs, that provides an error message on failure
> --------------------------------------------------------------
>
> Key: HDFS-4839
> URL: https://issues.apache.org/jira/browse/HDFS-4839
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 2.1.0-beta
> Reporter: Colin Patrick McCabe
> Priority: Minor
>
> It would be nice to have a variant of mkdirs that provided an error message
> explaining why it failed. This would make it easier to debug certain failing
> unit tests that rely on mkdir / mkdirs-- the ChecksumFilesystem tests, for
> example.
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