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https://issues.apache.org/jira/browse/HADOOP-5201?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12672609#action_12672609
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Steve Loughran commented on HADOOP-5201:
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Marshalling exceptions reliably over the wire is a big problem. All it takes is
for the code at the far end to have a JDBC driver that throws its own exception
for you to have something the caller can't understand. There is no way to
guarantee that someone submitting job has a classpath that matches exactly that
of the far end.
If you want to look at the (currently LGPL) code that we use for this, its here:
http://smartfrog.svn.sourceforge.net/viewvc/smartfrog/trunk/core/smartfrog/src/org/smartfrog/sfcore/common/SmartFrogExtractedException.java?view=markup
We run through the entire chain of faults, converting any that arent java.* or
javax.*, or a subclass of our own types, and extract out all the fault detail;
all the normal methods are overridden so this extract is not obvious, except of
course the classname. It is brittle against JVM version (I could throw a an
exception new to Java5, and against change in our libraries, but we felt it was
good enough.
I would propose having something like this, which could be used in multiple
places. Then tweak getDiagnostics() to return a list of events which could be
strings, exceptions or other useful facts added over time.
> getDiagnostics in TaskReport should return exceptions
> -----------------------------------------------------
>
> Key: HADOOP-5201
> URL: https://issues.apache.org/jira/browse/HADOOP-5201
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Reporter: Santhosh Srinivasan
>
> Currently, getDiagnostics() returns Strings. When exceptions are thrown in
> user code and/or Hadoop, it would be cleaner to propagate the exception back
> to the application for better error handling. Hadoop should return the
> exceptions instead of returning string representations that correspond to
> printStackTrace() output.
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