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https://issues.apache.org/jira/browse/HADOOP-13824?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15674194#comment-15674194
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Rob Vesse commented on HADOOP-13824:
------------------------------------
The command line is as follows:
{noformat}
hdfs dfs -D dfs.client.use.datanode.hostname=true -cat
hdfs://remote-namenode:8020/some/file
{noformat}
So I am attempting to talk to a Remote HDFS cluster where I can access the name
node but the data nodes are registered with internal IP addresses hence why I
want to use hostnames. I think the underlying cause is that the returned
hostnames are not resolvable on the machine where I run this command but since
the underlying error is suppressed I can't tell for certain.
Reproducing the specific case may be awkward because it appears to require
specific network configurations. However if you look at the code for
{{FsShell}} you should be able to see by inspection what I'm talking about.
Specifically there is a {{catch}} branch in {{FsShell.run()}} that does not log
the error and the {{displayError()}} method does not check that the provided
{{message}} argument is not {{null}}
I can probably provide a patch for this myself but I'm taking some time off
this weekend so it would be Monday at the earliest
> FsShell can suppress the real error if no error message is present
> ------------------------------------------------------------------
>
> Key: HADOOP-13824
> URL: https://issues.apache.org/jira/browse/HADOOP-13824
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs
> Affects Versions: 2.7.1, 2.7.3
> Reporter: Rob Vesse
> Assignee: John Zhuge
> Labels: supportability
>
> The {{FsShell}} error handling assumes in {{displayError()}} that the
> {{message}} argument is not {{null}}. However in the case where it is this
> leads to a NPE which results in suppressing the actual error information
> since a higher level of error handling kicks in and just dumps the stack
> trace of the NPE instead.
> e.g.
> {noformat}
> Exception in thread "main" java.lang.NullPointerException
> at org.apache.hadoop.fs.FsShell.displayError(FsShell.java:304)
> at org.apache.hadoop.fs.FsShell.run(FsShell.java:289)
> at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
> at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:84)
> at org.apache.hadoop.fs.FsShell.main(FsShell.java:340)
> {noformat}
> This is deeply unhelpful because depending on what the underlying error was
> there may be no stack dumped/logged for it (as HADOOP-7114 provides) since
> {{FsShell}} doesn't explicitly dump traces for {{IllegalArgumentException}}
> which appears to be the underlying cause of my issue. Line 289 is where
> {{displayError()}} is called for {{IllegalArgumentException}} handling and
> that catch clause does not log the error.
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