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