Thank you Kostas & Ufuk. I get into the following compilation error when I use
checkpointed interface. Pasting the code & message as follows:
Is the Serializable definition supposed to be from java.io.Serializable or
somewhere else?
Thanks again,
Buvana
================================================================================================================
Code:
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.streaming.api.checkpoint.Checkpointed;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.common.typeinfo.TypeHint;
import org.apache.flink.api.common.functions.RichFlatMapFunction;
import java.io.Serializable;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer09;
import org.apache.flink.streaming.util.serialization.SimpleStringSchema;
import org.apache.flink.util.Collector;
import java.util.Properties;
/**
* Created by buvana on 8/9/16.
*/
public class stateful {
private static String INPUT_KAFKA_TOPIC = null;
---
--- skipping the main as it’s the same as before except for class name change
-------------
---
public static class MapStateful extends RichFlatMapFunction<String,
Tuple2<String, Double>>
implements Checkpointed<Double> {
private Double prev_tuple = null;
@Override
public void flatMap(String incString, Collector<Tuple2<String, Double>>
out) {
try {
Double value = Double.parseDouble(incString);
System.out.println("value = " + value);
System.out.println(prev_tuple);
Double value2 = value - prev_tuple;
prev_tuple = value;
Tuple2<String, Double> tp = new Tuple2<String, Double>();
tp.setField(INPUT_KAFKA_TOPIC, 0);
tp.setField(value2, 1);
out.collect(tp);
} catch (NumberFormatException e) {
System.out.println("Could not convert to Float" + incString);
System.err.println("Could not convert to Float" + incString);
}
}
@Override
public void open(Configuration config) {
if (prev_tuple == null) {
// only recreate if null
// restoreState will be called before open()
// so this will already set the sum to the restored value
prev_tuple = new Double("0.0");
}
}
@Override
public Serializable snapshotState(
long checkpointId,
long checkpointTimestamp) throws Exception {
return prev_tuple;
}
@Override
public void restoreState(Double state) {
prev_tuple = state;
}
}
}
===============================================================================================================
ERROR message while building:
$ mvn clean package
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Flink Quickstart Job 0.1
[INFO] ------------------------------------------------------------------------
[WARNING] The artifact org.apache.commons:commons-io:jar:1.3.2 has been
relocated to commons-io:commons-io:jar:1.3.2
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ wiki-edits ---
[INFO] Deleting /home/buvana/flink/flink-1.1.0/wiki-edits/target
[INFO]
[INFO] --- maven-resources-plugin:2.3:resources (default-resources) @
wiki-edits ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ wiki-edits ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 7 source files to
/home/buvana/flink/flink-1.1.0/wiki-edits/target/classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR]
/home/buvana/flink/flink-1.1.0/wiki-edits/src/main/java/wikiedits/stateful.java:[116,19]
wikiedits.stateful.MapStateful is not abstract and does not override abstract
method snapshotState(long,long) in
org.apache.flink.streaming.api.checkpoint.Checkpointed
[ERROR]
/home/buvana/flink/flink-1.1.0/wiki-edits/src/main/java/wikiedits/stateful.java:[151,29]
snapshotState(long,long) in wikiedits.stateful.MapStateful cannot implement
snapshotState(long,long) in
org.apache.flink.streaming.api.checkpoint.Checkpointed
return type java.io.Serializable is not compatible with java.lang.Double
[ERROR]
/home/buvana/flink/flink-1.1.0/wiki-edits/src/main/java/wikiedits/stateful.java:[150,9]
method does not override or implement a method from a supertype
[INFO] 3 errors
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.171s
[INFO] Finished at: Thu Aug 11 10:47:07 EDT 2016
[INFO] Final Memory: 26M/660M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal
org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on
project wiki-edits: Compilation failure: Compilation failure:
[ERROR]
/home/buvana/flink/flink-1.1.0/wiki-edits/src/main/java/wikiedits/stateful.java:[116,19]
wikiedits.stateful.MapStateful is not abstract and does not override abstract
method snapshotState(long,long) in
org.apache.flink.streaming.api.checkpoint.Checkpointed
[ERROR]
/home/buvana/flink/flink-1.1.0/wiki-edits/src/main/java/wikiedits/stateful.java:[151,29]
snapshotState(long,long) in wikiedits.stateful.MapStateful cannot implement
snapshotState(long,long) in
org.apache.flink.streaming.api.checkpoint.Checkpointed
[ERROR] return type java.io.Serializable is not compatible with java.lang.Double
[ERROR]
/home/buvana/flink/flink-1.1.0/wiki-edits/src/main/java/wikiedits/stateful.java:[150,9]
method does not override or implement a method from a supertype
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e
switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please
read the following articles:
[ERROR] [Help 1]
http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
================================================================================================================
-----Original Message-----
From: Kostas Kloudas [mailto:k.klou...@data-artisans.com]
Sent: Thursday, August 11, 2016 10:34 AM
To: user@flink.apache.org
Subject: Re: flink - Working with State example
Exactly as Ufuk suggested, if you are not grouping your stream by key, you
should use the checkpointed interface.
The reason I asked before if you are using the keyBy() is because this is the
one that implicitly sets the keySerializer and scopes your (keyed) state to a
specific key.
If there is no keying, then keyed state cannot be used and the Checkpointed
interface should be used instead.
Let us know if you need anything else.
Kostas
> On Aug 11, 2016, at 4:10 PM, Ufuk Celebi <u...@apache.org> wrote:
>
> This only works for keyed streams, you have to use keyBy().
>
> You can use the Checkpointed interface instead
> (https://ci.apache.org/projects/flink/flink-docs-master/apis/streaming/state.html#checkpointing-instance-fields).
>
> On Thu, Aug 11, 2016 at 3:35 PM, Ramanan, Buvana (Nokia - US)
> <buvana.rama...@nokia-bell-labs.com> wrote:
>> Hi Kostas,
>>
>>
>>
>> Here is my code. All I am trying to compute is (x[t] – x[t-1]), where
>> x[t] is the current value of the incoming sample and x[t-1] is the
>> previous value of the incoming sample. I store the current value in
>> state store
>> (‘prev_tuple’) so that I can use it for computation in next cycle. As
>> you may observe, I am not using keyBy. I am simply printing out the
>> resultant tuple.
>>
>>
>>
>> It appears from the error message that I have to set the key
>> serializer (and possibly value serializer) for the state store. I am
>> not sure how to do that…
>>
>>
>>
>> Thanks for your interest in helping,
>>
>>
>>
>>
>>
>> Regards,
>>
>> Buvana
>>
>>
>>
>> public class stateful {
>>
>> private static String INPUT_KAFKA_TOPIC = null;
>>
>> private static int TIME_WINDOW = 0;
>>
>>
>>
>> public static void main(String[] args) throws Exception {
>>
>>
>>
>> if (args.length < 2) {
>>
>> throw new IllegalArgumentException("The application needs
>> two arguments. The first is the name of the kafka topic from which it has to
>> \n"
>>
>> + "fetch the data. The second argument is the size
>> of the window, in seconds, to which the aggregation function must be applied.
>> \n");
>>
>> }
>>
>>
>>
>> INPUT_KAFKA_TOPIC = args[0];
>>
>> TIME_WINDOW = Integer.parseInt(args[1]);
>>
>>
>>
>> Properties properties = null;
>>
>>
>>
>> properties = new Properties();
>>
>> properties.setProperty("bootstrap.servers", "localhost:9092");
>>
>> properties.setProperty("zookeeper.connect", "localhost:2181");
>>
>> properties.setProperty("group.id", "test");
>>
>>
>>
>> StreamExecutionEnvironment env =
>> StreamExecutionEnvironment.getExecutionEnvironment();
>>
>> //env.setStateBackend(new
>> FsStateBackend("file://home/buvana/flink/checkpoints"));
>>
>>
>>
>> DataStreamSource<String> stream = env
>>
>> .addSource(new
>> FlinkKafkaConsumer09<>(INPUT_KAFKA_TOPIC, new SimpleStringSchema(),
>> properties));
>>
>>
>>
>> // maps the data into Flink tuples
>>
>> DataStream<Tuple2<String,Double>> streamTuples =
>> stream.flatMap(new Rec2Tuple2());
>>
>>
>>
>> // write the result to the console or in a Kafka topic
>>
>> streamTuples.print();
>>
>>
>>
>> env.execute("plus one");
>>
>>
>>
>> }
>>
>>
>>
>> public static class Rec2Tuple2 extends RichFlatMapFunction<String,
>> Tuple2<String,Double> > {
>>
>> private transient ValueState<Tuple2<String, Double>>
>> prev_tuple;
>>
>>
>>
>> @Override
>>
>> public void flatMap(String incString, Collector<Tuple2<String,
>> Double>> out) throws Exception {
>>
>> try {
>>
>> Double value = Double.parseDouble(incString);
>>
>> System.out.println("value = " + value);
>>
>> Tuple2<String, Double> prev_stored_tp =
>> prev_tuple.value();
>>
>> System.out.println(prev_stored_tp);
>>
>>
>>
>> Double value2 = value - prev_stored_tp.f1;
>>
>> prev_stored_tp.f1 = value;
>>
>> prev_stored_tp.f0 = INPUT_KAFKA_TOPIC;
>>
>> prev_tuple.update(prev_stored_tp);
>>
>>
>>
>> Tuple2<String, Double> tp = new Tuple2<String,
>> Double>();
>>
>> tp.setField(INPUT_KAFKA_TOPIC, 0);
>>
>> tp.setField(value2, 1);
>>
>> out.collect(tp);
>>
>>
>>
>> } catch (NumberFormatException e) {
>>
>> System.out.println("Could not convert to Float" +
>> incString);
>>
>> System.err.println("Could not convert to Float" +
>> incString);
>>
>> }
>>
>> }
>>
>>
>>
>> @Override
>>
>> public void open(Configuration config) {
>>
>> ValueStateDescriptor<Tuple2<String, Double>> descriptor =
>>
>> new ValueStateDescriptor<>(
>>
>> "previous input value", // the state name
>>
>> TypeInformation.of(new
>> TypeHint<Tuple2<String,
>> Double>>() {}), // type information
>>
>> Tuple2.of("test topic", 0.0)); // default
>> value of the state, if nothing was set
>>
>> prev_tuple = getRuntimeContext().getState(descriptor);
>>
>> }
>>
>> }
>>
>> }
>>
>>
>>
>> From: Kostas Kloudas [mailto:k.klou...@data-artisans.com]
>> Sent: Thursday, August 11, 2016 5:45 AM
>> To: user@flink.apache.org
>> Subject: Re: flink - Working with State example
>>
>>
>>
>> Hello Buvana,
>>
>>
>>
>> Can you share a bit more details on your operator and how you are using it?
>>
>> For example, are you using keyBy before using you custom operator?
>>
>>
>>
>> Thanks a lot,
>>
>> Kostas
>>
>>
>>
>> On Aug 10, 2016, at 10:03 PM, Ramanan, Buvana (Nokia - US)
>> <buvana.rama...@nokia-bell-labs.com> wrote:
>>
>>
>>
>> Hello,
>>
>>
>>
>> I am utilizing the code snippet in:
>> https://ci.apache.org/projects/flink/flink-docs-master/apis/streaming
>> /state.html and particularly ‘open’ function in my code:
>>
>> @Override
>>
>> public void open(Configuration config) {
>>
>> ValueStateDescriptor<Tuple2<Long, Long>> descriptor =
>>
>> new ValueStateDescriptor<>(
>>
>> "average", // the state name
>>
>> TypeInformation.of(new TypeHint<Tuple2<Long,
>> Long>>() {}), // type information
>>
>> Tuple2.of(0L, 0L)); // default value of the
>> state, if nothing was set
>>
>> sum = getRuntimeContext().getState(descriptor);
>>
>> }
>>
>>
>>
>> When I run, I get the following error:
>>
>> Caused by: java.lang.RuntimeException: Error while getting state
>>
>> at
>> org.apache.flink.streaming.api.operators.StreamingRuntimeContext.getS
>> tate(StreamingRuntimeContext.java:120)
>>
>> at
>> wikiedits.stateful$Rec2Tuple2.open(stateful.java:103)
>>
>> at
>> org.apache.flink.api.common.functions.util.FunctionUtils.openFunction
>> (FunctionUtils.java:38)
>>
>> at
>> org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator.op
>> en(AbstractUdfStreamOperator.java:91)
>>
>> at
>> org.apache.flink.streaming.api.operators.StreamFlatMap.open(StreamFla
>> tMap.java:41)
>>
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.openAllOperators(
>> StreamTask.java:314)
>>
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask
>> .java:214)
>>
>> at
>> org.apache.flink.runtime.taskmanager.Task.run(Task.java:559)
>>
>> at java.lang.Thread.run(Thread.java:745)
>>
>> Caused by: java.lang.Exception: State key serializer has not been
>> configured in the config. This operation cannot use partitioned state.
>>
>> at
>> org.apache.flink.runtime.state.AbstractStateBackend.getPartitionedSta
>> te(AbstractStateBackend.java:199)
>>
>> at
>> org.apache.flink.streaming.api.operators.AbstractStreamOperator.getPa
>> rtitionedState(AbstractStreamOperator.java:260)
>>
>> at
>> org.apache.flink.streaming.api.operators.StreamingRuntimeContext.getS
>> tate(StreamingRuntimeContext.java:118)
>>
>> ... 8 more
>>
>>
>>
>> Where do I define the key & value serializer for state?
>>
>>
>>
>> Thanks,
>>
>> Buvana
>>
>>
