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From "Brian Dougan (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CRUNCH-266) AvroSpecificDeepCopier needs to use constructor on SpecificDatumReader that takes a class.
Date Mon, 16 Sep 2013 18:16:53 GMT
Brian Dougan created CRUNCH-266:
-----------------------------------

             Summary: 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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