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From "Timo Walther (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (FLINK-4872) Type erasure problem exclusively on cluster execution
Date Tue, 29 Nov 2016 09:13:58 GMT

     [ https://issues.apache.org/jira/browse/FLINK-4872?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Timo Walther resolved FLINK-4872.
---------------------------------
       Resolution: Fixed
    Fix Version/s: 1.2.0

Fixed in 3a27f55cfa03a96cb7aff5d25a6402a283be7b45.

> Type erasure problem exclusively on cluster execution
> -----------------------------------------------------
>
>                 Key: FLINK-4872
>                 URL: https://issues.apache.org/jira/browse/FLINK-4872
>             Project: Flink
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.1.2
>            Reporter: Martin Junghanns
>            Assignee: Timo Walther
>             Fix For: 1.2.0
>
>
> The following codes runs fine on local and collection execution environment but fails
when executed on a cluster.
> {code:title=Problem.java}
> import org.apache.flink.api.common.functions.MapFunction;
> import org.apache.flink.api.java.DataSet;
> import org.apache.flink.api.java.ExecutionEnvironment;
> import org.apache.flink.api.java.tuple.Tuple1;
> import java.lang.reflect.Array;
> public class Problem {
>   public static class Pojo {
>   }
>   public static class Foo<T> extends Tuple1<T> {
>   }
>   public static class Bar<T> extends Tuple1<T[]> {
>   }
>   public static class UDF<T> implements MapFunction<Foo<T>, Bar<T>>
{
>     private final Class<T> clazz;
>     public UDF(Class<T> clazz) {
>       this.clazz = clazz;
>     }
>     @Override
>     public Bar<T> map(Foo<T> value) throws Exception {
>       Bar<T> bar = new Bar<>();
>       //noinspection unchecked
>       bar.f0 = (T[]) Array.newInstance(clazz, 10);
>       return bar;
>     }
>   }
>   public static void main(String[] args) throws Exception {
>     // runs in local, collection and cluster execution
>     withLong();
>     // runs in local and collection execution, fails on cluster execution
>     withPojo();
>   }
>   public static void withLong() throws Exception {
>     ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
>     Foo<Long> foo = new Foo<>();
>     foo.f0 = 42L;
>     DataSet<Foo<Long>> barDataSource = env.fromElements(foo);
>     DataSet<Bar<Long>> map = barDataSource.map(new UDF<>(Long.class));
>     map.print();
>   }
>   public static void withPojo() throws Exception {
>     ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
>     Foo<Pojo> foo = new Foo<>();
>     foo.f0 = new Pojo();
>     DataSet<Foo<Pojo>> barDataSource = env.fromElements(foo);
>     DataSet<Bar<Pojo>> map = barDataSource.map(new UDF<>(Pojo.class));
>     map.print();
>   }
> }
> {code}
> {code:title=ProblemTest.java}
> import org.apache.flink.test.util.MultipleProgramsTestBase;
> import org.junit.Test;
> import org.junit.runner.RunWith;
> import org.junit.runners.Parameterized;
> @RunWith(Parameterized.class)
> public class ProblemTest extends MultipleProgramsTestBase {
>   public ProblemTest(TestExecutionMode mode) {
>     super(mode);
>   }
>   @Test
>   public void testWithLong() throws Exception {
>     Problem.withLong();
>   }
>   @Test
>   public void testWithPOJO() throws Exception {
>     Problem.withPojo();
>   }
> }
> {code}
> Exception:
> {code}
> The return type of function 'withPojo(Problem.java:58)' could not be determined automatically,
due to type erasure. You can give type information hints by using the returns(...) method
on the result of the transformation call, or by letting your function implement the 'ResultTypeQueryable'
interface.
>     org.apache.flink.api.java.DataSet.getType(DataSet.java:178)
>     org.apache.flink.api.java.DataSet.collect(DataSet.java:407)
>     org.apache.flink.api.java.DataSet.print(DataSet.java:1605)
>     Problem.withPojo(Problem.java:60)
>     Problem.main(Problem.java:38) 
> {code}



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