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https://issues.apache.org/jira/browse/MAPREDUCE-1686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12888358#action_12888358
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Paul Burkhardt commented on MAPREDUCE-1686:
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Okay, I'll try and do that.
Paul
> ClassNotFoundException for custom format classes provided in libjars
> --------------------------------------------------------------------
>
> Key: MAPREDUCE-1686
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1686
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: contrib/streaming
> Affects Versions: 0.20.2
> Reporter: Paul Burkhardt
> Priority: Minor
>
> The StreamUtil::goodClassOrNull method assumes user-provided classes have
> package names and if not, they are part of the Hadoop Streaming package. For
> example, using custom InputFormat or OutputFormat classes without package
> names will fail with a ClassNotFound exception which is not indicative given
> the classes are provided in the libjars option. Admittedly, most Java
> packages should have a package name so this should rarely come up.
> Possible resolution options:
> 1) modify the error message to include the actual classname that was
> attempted in the goodClassOrNull method
> 2) call the Configuration::getClassByName method first and if class not found
> check for default package name and try the call again
> {code}
> public static Class goodClassOrNull(Configuration conf, String className,
> String defaultPackage) {
> Class clazz = null;
> try {
> clazz = conf.getClassByName(className);
> } catch (ClassNotFoundException cnf) {
> }
> if (clazz == null) {
> if (className.indexOf('.') == -1 && defaultPackage != null) {
> className = defaultPackage + "." + className;
> try {
> clazz = conf.getClassByName(className);
> } catch (ClassNotFoundException cnf) {
> }
> }
> }
> return clazz;
> }
> {code}
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