[AVRO-1240] SpecificDataumReader.next() can return a GenericData.Record resulting in a ClassCastException

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.7.3
• Fix Version/s: 1.7.4
• Component/s: java
• Assignee: Doug Cutting
• Reporter: Brock Noland
• Created: 01/Feb/13 16:23
• Updated: 27/Feb/13 00:54
• Resolved: 05/Feb/13 14:47

Description

The following reasonable code:

    DatumReader<Test> reader = new SpecificDatumReader<Test>(Test.class); 
    DataFileReader<Test> dataFileReader = new DataFileReader<Test>(file, reader); 
    Test datum = null;
    while(dataFileReader.hasNext()) { 
      datum = dataFileReader.next(datum); 
      System.out.println(datum); 
    }

Can result in a runtime exception:

$ java -cp avro-1.7.3.jar:$(hadoop classpath) org.apache.hadoop.util.RunJar target/avro-example-1.0-jar-with-dependencies.jar Sample target/test-file 
Exception in thread "main" java.lang.ClassCastException: org.apache.avro.generic.GenericData$Record cannot be cast to Test
	at Sample.main(Sample.java:27)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.hadoop.util.RunJar.main(RunJar.java:208)

when the jar containing the specific class (Test in my example) is loaded from a different classloader than the avro jar itself. This occurs when run via the hadoop jar command but could occur in web containers or other locations as well.

Issue Links

• relates to: AVRO-1103 New AvroDeserializer should Locate Appropriate Classloader