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https://issues.apache.org/jira/browse/FLINK-4624?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15505926#comment-15505926
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Martin Junghanns commented on FLINK-4624:
-----------------------------------------
You were right, I had a private member in the UDF for object reuse which caused
the serialization issue. The Either type now works as expected. However, since
I now need to add return type information, I am running into another issue.
This is how I create the type info:
{code:java}
TypeInformation<K> keyType = ((TupleTypeInfo<?>)
input.getVertices().getType()).getTypeAt(0);
TypeInformation<VV> valueType = ((TupleTypeInfo<?>)
input.getVertices().getType()).getTypeAt(1);
EitherTypeInfo<VV, NullValue> eitherType = new EitherTypeInfo<>(valueType,
TypeInformation.of(NullValue.class));
TupleTypeInfo<VertexGroupItem<K, VV>> tupleTypeInfo = new
TupleTypeInfo<>(keyType, keyType, eitherType, BasicTypeInfo.LONG_TYPE_INFO);
{code}
(which for example leads to "Java *Tuple4*<Long, Long, Either <Long,
ValueType<NullValue>>, Long>" according to the debugger)
The first transformation (GroupReduce) that produces these tuples returns that
type. A subsequent filter transformation fails with:
{{java.lang.ClassCastException: org.apache.flink.api.java.tuple.Tuple4 cannot
be cast to org.apache.flink.graph.library.Summarization$VertexGroupItem}}
Adding the return type info to the filter did not help. Any ideas? Thanks for
your help.
> Gelly's summarization algorithm cannot deal with null vertex group values
> -------------------------------------------------------------------------
>
> Key: FLINK-4624
> URL: https://issues.apache.org/jira/browse/FLINK-4624
> Project: Flink
> Issue Type: Bug
> Components: Gelly
> Reporter: Till Rohrmann
> Assignee: Martin Junghanns
> Fix For: 1.2.0
>
>
> Gelly's {{Summarization}} algorithm cannot handle null values in the
> `VertexGroupItem.f2`. This behaviour is hidden by using Strings as a vertex
> value in the {{SummarizationITCase}}, because the {{StringSerializer}} can
> handle null values.
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