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https://issues.apache.org/jira/browse/HADOOP-5700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12714324#action_12714324
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Todd Lipcon commented on HADOOP-5700:
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bq. The patch introduces a redundant check, which degrades the namenode
performance. All production systems will suffer this. The performance impact is
still unknown since no performance measurement is even done.
I strongly disagree on the performance issue. I'd go into detail about why this
cannot possibly cause a performance problem, but clearly this is an idealogical
debate rather than a practical one for this case. In short: the data accessed
is about to be split, meaning that it can't be an extra cache miss, and the
splitting and allocation will be several of orders of magnitude slower than a
constant-time single-byte comparison.
bq. The patch uses "/" but not the Path.SEPARATOR constant. It is incorrect,
strictly speaking.
Good point. That should be fixed.
bq. The patch does not fix any bug: it changes NPE to IAE. Both of them are
uncaught runtime exceptions
I think of IAEs as stricly more informative than NPEs for the developer who has
committed the error. Again, no sense continuing that discussion.
bq. As mentioned by Todd's earlier comment, parameter validation should be
happening at the outer layers of the API but not internal methods. However, the
patch does parameter validation in INode.getPathComponents(..) which is an
internal method.
Also should be fixed.
I'll prepare a patch to address the above things.
On a side note, what is the policy for dealing with updated patches after a
JIRA has already been committed? As far as I knew, discussion of a better/new
patch is supposed to go on in a new JIRA.
> INode.getPathComponents throws NPE when given a non-absolute path
> -----------------------------------------------------------------
>
> Key: HADOOP-5700
> URL: https://issues.apache.org/jira/browse/HADOOP-5700
> Project: Hadoop Core
> Issue Type: Bug
> Components: dfs
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Minor
> Fix For: 0.21.0
>
> Attachments: HADOOP-5700.txt
>
>
> If you pass a path that doesn't start with '/' to INode.getPathComponents, it
> throws a NullPointerException. Instead it should throw
> IllegalArgumentException to make it clear that absolute paths are required in
> this code.
> The attached patch fixes this, clarifies, the javadoc, and adds a test case.
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