Gabor Gevay created FLINK-2447:
----------------------------------
Summary: TypeExtractor returns wrong type info when a Tuple has
two fields of the same POJO type
Key: FLINK-2447
URL: https://issues.apache.org/jira/browse/FLINK-2447
Project: Flink
Issue Type: Bug
Reporter: Gabor Gevay
Consider the following code:
DataSet<FooBarPojo> d1 = env.fromElements(new FooBarPojo());
DataSet<Tuple2<FooBarPojo, FooBarPojo>> d2 = d1.map(new
MapFunction<FooBarPojo, Tuple2<FooBarPojo, FooBarPojo>>() {
@Override
public Tuple2<FooBarPojo, FooBarPojo> map(FooBarPojo
value) throws Exception {
return null;
}
});
where FooBarPojo is the following type:
public class FooBarPojo {
public int foo, bar;
public FooBarPojo() {}
}
This should print a tuple type with two identical fields:
Java Tuple2<PojoType<FooBarPojo, fields = [bar: Integer, foo: Integer]>,
PojoType<FooBarPojo, fields = [bar: Integer, foo: Integer]>>
But it prints the following instead:
Java Tuple2<PojoType<FooBarPojo, fields = [bar: Integer, foo: Integer]>,
GenericType<FooBarPojo>>
Note, that this problem causes some co-groups in Gelly to crash with
"org.apache.flink.api.common.InvalidProgramException: The pair of co-group keys
are not compatible with each other" when the vertex ID type is a POJO, because
the second field of the Edge type gets to be a generic type, but the POJO gets
recognized in the Vertex type, and getNumberOfKeyFields returns different
numbers for the POJO and the generic type.
The source of the problem is the mechanism in TypeExtractor that would detect
recursive types (see the "alreadySeen" field in TypeExtractor), as it mistakes
the second appearance of FooBarPojo with a recursive field.
Specifically the following happens: createTypeInfoWithTypeHierarchy
starts to process the Tuple2<FooBarPojo, FooBarPojo> type, and in line 434 it
calls itself for the first field, which proceeds into the privateGetForClass
case which correctly detects that it is a POJO, and correctly returns a
PojoTypeInfo; but in the meantime in line 1191, privateGetForClass adds
PojoTypeInfo to "alreadySeen". Then the outer createTypeInfoWithTypeHierarchy
approaches the second field, goes into privateGetForClass, which mistakenly
returns a GenericTypeInfo, as it thinks in line 1187, that a recursive type is
being processed.
(Note, that if we comment out the recursive type detection (the lines that do
their thing with the alreadySeen field), then the output is correct.)
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
