[jira] [Commented] (HADOOP-9861) Invert ReflectionUtils' stack trace

["Alejandro Abdelnur (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-9861?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13736983#comment-13736983 ] 

Alejandro Abdelnur commented on HADOOP-9861:
--------------------------------------------

If we do this, and we don't clearly state we are doing an inversion, it will disorient anybody looking at the trace.
                
> Invert ReflectionUtils' stack trace
> -----------------------------------
>
>                 Key: HADOOP-9861
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9861
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: util
>    Affects Versions: 2.0.5-alpha
>            Reporter: Harsh J
>            Assignee: Daisuke Kobayashi
>
> Often an MR task (as an example) may fail at the configure stage due to a misconfiguration or whatever, and the only thing a user gets by virtue of MR pulling limited bytes of the diagnostic error data is the top part of the stacktrace:
> {code}
> java.lang.RuntimeException: Error in configuring object
>     at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:93)
>     at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:64)
>     at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:117)
>     at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:432)
>     at org.apache.hadoop.mapred.MapTask.run(MapTask.java:372)
>     at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
> {code}
> This is absolutely useless to a user, and he also goes ahead and blames the framework for having an issue, rather than thinking (non-intuitively) to go see the whole task log for the full trace, especially the last part.
> Hundreds of time its been a mere class thats missing, etc. but there's just too much pain involved here to troubleshoot.
> Would be much much better, if we inverted the trace. For example, here's what Hive can return back if we did so, for a random trouble I pulled from the web:
> {code}
> java.lang.RuntimeException: Error in configuring object
> Caused by: java.lang.NullPointerException
>     at org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector.toString(StructObjectInspector.java:64)
>     at java.lang.String.valueOf(String.java:2826)
>     at java.lang.StringBuilder.append(StringBuilder.java:115)
>     at org.apache.hadoop.hive.ql.exec.UnionOperator.initializeOp(UnionOperator.java:110)
>     at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:375)
>     at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:451)
>     at org.apache.hadoop.hive.ql.exec.Operator.initializeChildren(Operator.java:407)
>     at org.apache.hadoop.hive.ql.exec.TableScanOperator.initializeOp(TableScanOperator.java:186)
>     at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:375)
>     at org.apache.hadoop.hive.ql.exec.MapOperator.initializeOp(MapOperator.java:563)
>     at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:375)
>     at org.apache.hadoop.hive.ql.exec.ExecMapper.configure(ExecMapper.java:100)
>     ... 22 more
> {code}
> This way the user can at least be sure what part's really failing, and not get lost trying to work their way through reflection utils and upwards/downwards.

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