Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
Locked
Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
 
|
Hi, I am trying to use the KeyedStream with Tuple to handle diffrent types of Tuples including Tuple6. Keep getting the Exception: Exception in thread "main" org.apache.flink.api.common.functions.InvalidTypesException: Usage of class Tuple as a type is not allowed. Use a concrete subclass (e.g. Tuple1, Tuple2, etc.) instead. Is there a way around Type Erasure here ? I want to use KeyedStream<Monitoring, Tuple> so that I can pass it on to treat Tuple6 as a Tuple like the monitoringTupleKeyedStream. Code below: KeyedStream<Monitoring, Tuple> monitoringTupleKeyedStream = null; This example below needs monitoringTupleKeyedStream to be KeyedStream<Monitoring, Tuple6<String, String, String, String, String, String>> TypeInformation<Tuple6<String, String, String, String, String, String>> info = TypeInformation.of(new TypeHint<Tuple6<String, String, String, String, String, String>>(){}); TIA |
Re: Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
|
|
Flink needs type information for serializing and deserializing objects, and that is lost due to Java type erasure. The only way to workaround this is to specify the return type of the function called in the lambda. Fabian's answer here explains it well. Tim On Tue, Apr 2, 2019, 7:03 PM Vijay Balakrishnan <[hidden email]> wrote:
|
Re: Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
|
|
Hi Tim, Thanks for your reply. I am not seeing an option to specify a .returns(new TypeHint<Tuple6<String, String,String,String,String,String>>(){}) with KeyedStream ?? monitoringTupleKeyedStream = kinesisStream.keyBy(new KeySelector<Monitoring, Tuple>() { I tried using TypeInformation<Tuple6<String, String, String, String, String, String>> info = TypeInformation.of(new TypeHint<Tuple6<String, String, String, String, String, String>>(){}); kinesisStream.keyBy(new KeySelector<Monitoring, Tuple>() {...}, info); //specify typeInfo through TIA, Vijay On Tue, Apr 2, 2019 at 6:06 PM Timothy Victor <[hidden email]> wrote:
|
Re: Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
|
|
> I tried using [
keyBy(KeySelector, TypeInformation) ]
What was the result of this approach? On 03/04/2019 17:36, Vijay Balakrishnan wrote:
|
Re: Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
|
|
Could this just be solved by creating a POJO model class for your problem? That is, instead of using Tuple6 - create a class that encapsulates your data. This, I think, would solve your problem. But beyond that I think the code will be more understandable. It's hard to have a Tuple6 of all Strings, and remember what each one means -- even if I wrote the code :-) Furthermore, if and when you need to add more elements to your data model, you will need to refactor your entire Flink graph. Keeping a data model in POJO protects against those things. The latter is just unsolicited code review feedback. And I know I gave it without much context to your problem. So please take with a large grain of salt, and if it doesn't apply just ignore it. Tim On Fri, Apr 5, 2019 at 7:53 AM Chesnay Schepler <[hidden email]> wrote:
|
Re: Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
|
|
I agree with Timothy, POJO would be a much better approach. However, If you are trying to build some generic framework and for different streams, there would be different fields, you can follow the Map approach. For the latter approach, you need to write extra mapper class which will convert all the fields in the stream to the Map based stream. Abhishek On Sun, Apr 7, 2019 at 3:07 AM Timothy Victor <[hidden email]> wrote:
|
Re: Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
|
|
Thx for all your replies. Solved the problem by skirting the issue. I pre-populated the incoming Monitoring Object on intake with the dynamic runtime fields keyName and keyValue and that way, I could use the static call as used in all the other if conditions: monitoringTupleKeyedStream = kinesisStream.keyBy("deployment", "gameId", "eventName", "component", "keyName","keyValue"); The reason, I want to use Tuple was because I was passing this KeyedStream<Monitoring, Tuple> to a common method that could handle the Tuple accordingly. I tried using [ keyBy(KeySelector, TypeInformation) ] but the compiler complained that I need to use Monitoring, Tuple6 in that particular case. Vijay On Sun, Apr 7, 2019 at 5:40 PM abhishek sharma <[hidden email]> wrote:
|
Re: Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
|
|
In reply to this post by abhishek sharma
Hi, Had asked this questions earlier as topic - "Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple" Having issues defining a generic Tuple instead of a specific Tuple1,Tuple2 etc. Exception in thread "main" org.apache.flink.api.common.functions.InvalidTypesException: Usage of class Tuple as a type is not allowed. Use a concrete subclass (e.g. Tuple1, Tuple2, etc.) instead. DataStream<Map<String, Object>> kinesisStream = ...; KeyedStream<Map<String, Object>, Tuple> monitoringTupleKeyedStream = kinesisStream.keyBy(new MapTupleKeySelector(groupBySet));//<===== complains about Tuple type for monitoringTupleKeyedStream ..... public static class MapTupleKeySelector implements KeySelector<Map<String, Object>, Tuple> { private final Set<String> groupBySet; public MapTupleKeySelector(Set<String> groupBySet) { this.groupBySet = groupBySet; } @Override public Tuple getKey(Map<String, Object> inputMap) throws Exception { int groupBySetSize = groupBySet.size(); Tuple tuple = Tuple.newInstance(groupBySetSize); //Tuple1 tuple = new Tuple1(); int count = 0; for (String groupBy : groupBySet) { tuple.setField(groupByValue, count++); } return tuple; } } Abhishek had replied back in the Thread as follows: (posting in that thread as well creating a new thread): However, If you are trying to build some generic framework and for different streams, there would be different fields, you can follow the Map approach. For the latter approach, you need to write extra mapper class which will convert all the fields in the stream to the Map based stream. Can I get an example of how to create this extra Mapper class ? Currently, I am using deserialization to convert the incoming byte[] by implementing KinesisDeserializationSchema<Map<String, Object>> to convert to a DataStream<Map<String, Object>> kinesisStream. TIA, On Sun, Apr 7, 2019 at 5:40 PM abhishek sharma <[hidden email]> wrote:
|
Re: Flink - Type Erasure Exception trying to use Tuple6 instead of Tuple
|
|
I solved the problem by following another person's recommendation on the other post about using a wrapper POJO. So, I used a wrapper MonitoringTuple to wrap the Tuple and that solved my problem with varying number of fields in the Tuple interface. public class MonitoringTuple { Then, I used it like this: KeyedStream<Map<String, Object>, MonitoringTuple> monitoringTupleKeyedStream = kinesisStream.keyBy(new MapTupleKeySelector(groupBySet)); The MapTupleKeySelector is defined below: public static class MapTupleKeySelector implements KeySelector<Map<String, Object>, MonitoringTuple> { private final Set<String> groupBySet; public MapTupleKeySelector(Set<String> groupBySet) { this.groupBySet = groupBySet; } @Override public MonitoringTuple getKey(Map<String, Object> inputMap) { int groupBySetSize = groupBySet.size(); Tuple tuple = Tuple.newInstance(groupBySetSize); int count = 0; for (String groupBy : groupBySet) { count = setTupleField(inputMap, tuple, count, groupBy); } return new MonitoringTuple(tuple); } } public static int setTupleField(Map<String, Object> inputMap, Tuple tuple, int count, String groupBy) { Object groupByValueObj = inputMap.get(groupBy); String tupleValue = Utils.convertToString(groupByValueObj); tuple.setField(tupleValue, count++); return count; } } TIA, On Wed, May 1, 2019 at 1:39 PM Vijay Balakrishnan <[hidden email]> wrote:
|
«
Return to (DEPRECATED) Apache Flink User Mailing List archive.
|
1 view|%1 views
| Free forum by Nabble | Edit this page |