Hi Kostas,
I am trying to use FsStateBackend as the backend for storing state. And
configure it as follows in the code:
StreamExecutionEnvironment env =
StreamExecutionEnvironment.getExecutionEnvironment();
env.setStateBackend(new
FsStateBackend("file:///home/buvana/flink/checkpoints"));
env.enableCheckpointing(10000);
everything else is same as the code I shared with you previously.
When I execute, I see that a directory is created under
/home/buvana/flink/checkpoints, but there is nothing under that directory.
I was expecting to find some file / sub dir there.
Please explain.
Thanks,
Buvana
-----Original Message-----
From: Kostas Kloudas [mailto:k.klou...@data-artisans.com]
Sent: Friday, August 12, 2016 1:37 AM
To: user@flink.apache.org
Subject: Re: flink - Working with State example
No problem!
Regards,
Kostas
> On Aug 12, 2016, at 3:00 AM, Ramanan, Buvana (Nokia - US)
> <buvana.rama...@nokia-bell-labs.com> wrote:
>
> Kostas,
> Good catch! That makes it working! Thank you so much for the help.
> Regards,
> Buvana
>
> -----Original Message-----
> From: Kostas Kloudas [mailto:k.klou...@data-artisans.com]
> Sent: Thursday, August 11, 2016 11:22 AM
> To: user@flink.apache.org
> Subject: Re: flink - Working with State example
>
> Hi Buvana,
>
> At a first glance, your snapshotState() should return a Double.
>
> Kostas
>
>> On Aug 11, 2016, at 4:57 PM, Ramanan, Buvana (Nokia - US)
>> <buvana.rama...@nokia-bell-labs.com> wrote:
>>
>> 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/stat
>> eful.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/stat
>> eful.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/stat
>> eful.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/stat
>> eful.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/stat
>> eful.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/stat
>> eful.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/streamin
>>>> g /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.get
>>>> S
>>>> tate(StreamingRuntimeContext.java:120)
>>>>
>>>> at
>>>> wikiedits.stateful$Rec2Tuple2.open(stateful.java:103)
>>>>
>>>> at
>>>> org.apache.flink.api.common.functions.util.FunctionUtils.openFunctio
>>>> n
>>>> (FunctionUtils.java:38)
>>>>
>>>> at
>>>> org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator.o
>>>> p
>>>> en(AbstractUdfStreamOperator.java:91)
>>>>
>>>> at
>>>> org.apache.flink.streaming.api.operators.StreamFlatMap.open(StreamFl
>>>> a
>>>> tMap.java:41)
>>>>
>>>> at
>>>> org.apache.flink.streaming.runtime.tasks.StreamTask.openAllOperators
>>>> (
>>>> StreamTask.java:314)
>>>>
>>>> at
>>>> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTas
>>>> k
>>>> .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.getPartitionedSt
>>>> a
>>>> te(AbstractStateBackend.java:199)
>>>>
>>>> at
>>>> org.apache.flink.streaming.api.operators.AbstractStreamOperator.getP
>>>> a
>>>> rtitionedState(AbstractStreamOperator.java:260)
>>>>
>>>> at
>>>> org.apache.flink.streaming.api.operators.StreamingRuntimeContext.get
>>>> S
>>>> tate(StreamingRuntimeContext.java:118)
>>>>
>>>> ... 8 more
>>>>
>>>>
>>>>
>>>> Where do I define the key & value serializer for state?
>>>>
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Buvana
>>>>
>>>>
>>
>
