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Posted to dev@crunch.apache.org by "Josh Wills (JIRA)" <ji...@apache.org> on 2013/09/16 20:18:53 UTC
[jira] [Commented] (CRUNCH-266) AvroSpecificDeepCopier needs to use
constructor on SpecificDatumReader that takes a class.
[ https://issues.apache.org/jira/browse/CRUNCH-266?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13768570#comment-13768570 ]
Josh Wills commented on CRUNCH-266:
-----------------------------------
Man, do I hate that bug. Is the patch we need just a one-liner, or do we need to update Avro as well?
> AvroSpecificDeepCopier needs to use constructor on SpecificDatumReader that takes a class.
> ------------------------------------------------------------------------------------------
>
> Key: CRUNCH-266
> URL: https://issues.apache.org/jira/browse/CRUNCH-266
> Project: Crunch
> Issue Type: Bug
> Components: Core
> Affects Versions: 0.7.0
> Reporter: Brian Dougan
> Assignee: Josh Wills
> Priority: Minor
>
> As per https://issues.apache.org/jira/browse/AVRO-1240, when the avro jar is in a parent classloader of the classloader that contains SpecificData classes, a ClassCastException can occur if you don't use the SpecificDatumReader constructor that takes a class (and accounts for the classloader).
> Since standard hadoop commands seem to use parent classloaders, and avro is included in the hadoop parent classloader, this issue can be seen if you run a command from a jar including SpecificData classes that attempts to use them from the hadoop command (such as materializing a PCollection of avro objects.
> It looks like all that is needed is to update AvroSpecificDatumReader to call a different constructor.
> * public SpecificDatumReader(Class<T> c)
> To add in more confusion, since avro is an included hadoop dependency, and avro itself had a bug until 1.7.4, this fix will only work if avro in hadoop has been updated to 1.7.4 (or is running on a version that has already done this).
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