state store may have migrated to another instance

问题

when i try to access state stere from stream, am getting below error,

The state store, count-store, may have migrated to another instance

when i tried to access ReadOnlyKeyValueStore from store, getting erorr message as migrated to other server. but am having only one broker is up and running

/**
 * 
 */
package com.ms.kafka.com.ms.stream;

import java.util.Properties;
import java.util.stream.Stream;

import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.errors.InvalidStateStoreException;
import org.apache.kafka.streams.kstream.Consumed;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.KTable;
import org.apache.kafka.streams.kstream.Materialized;
import org.apache.kafka.streams.state.QueryableStoreType;
import org.apache.kafka.streams.state.QueryableStoreTypes;
import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;

import com.ms.kafka.com.ms.entity.TrackingEvent;
import com.ms.kafka.com.ms.entity.TrackingEventDeserializer;
import com.ms.kafka.com.ms.entity.TrackingEvnetSerializer;


/**
 * @author vettri
 *
 */
public class EventStreamer {

    /**
     * 
     */
    public EventStreamer() {
        // TODO Auto-generated constructor stub
    }

    public static void main(String[] args) throws InterruptedException {
        Properties props = new Properties();
        props.put(StreamsConfig.APPLICATION_ID_CONFIG, "trackeventstream_stream");
        props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        props.put(StreamsConfig.CLIENT_ID_CONFIG,"testappdi");
        props.put("auto.offset.reset","earliest");
        /*
         * props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG,
         * Serdes.String().getClass());
         * props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG,
         * Serdes.String().getClass());
         */

        final StreamsBuilder builder = new StreamsBuilder();
        final KStream<String , TrackingEvent> eventStream = builder.stream("rt_event_command_topic_stream",Consumed.with(Serdes.String(),
                Serdes.serdeFrom(new TrackingEvnetSerializer(), new TrackingEventDeserializer())));
        KTable<String, Long> groupedByUniqueId = eventStream.groupBy((k,v) -> v.getUniqueid()).
                count(Materialized.as("count-store"));

        /*
         * KTable<Integer, Integer> table = builder.table( "rt_event_topic_stream",
         * Materialized.as("queryable-store-name"));
         */

        //eventStream.filter((k,v) -> "9de3b676-b20f-4b7a-878b-526fd5948a34".equalsIgnoreCase(v.getUniqueid())).foreach((k,v) -> System.out.println(v));
        final KafkaStreams stream = new KafkaStreams(builder.build(), props);
        stream.cleanUp();
        stream.start();
        System.out.println("Strema state : "+stream.state().name());
        String queryableStoreName = groupedByUniqueId.queryableStoreName();
        /*
         * ReadOnlyKeyValueStore keyValStore1 =
         * waitUntilStoreIsQueryable(queryableStoreName, (QueryableStoreTypes)
         * QueryableStoreTypes.keyValueStore(),stream);
         */ ReadOnlyKeyValueStore<Long , TrackingEvent> keyValStore = stream.store(queryableStoreName, QueryableStoreTypes.<Long,TrackingEvent>keyValueStore());

       // System.out.println("results --> "+keyValStore.get((long) 158));
        //streams.close();
    }

    public static <T> T waitUntilStoreIsQueryable(final String storeName,
            final QueryableStoreTypes queryableStoreType, final KafkaStreams streams) throws InterruptedException {
        while (true) {
            try {
                return streams.store(storeName, (QueryableStoreType<T>) queryableStoreType);
            } catch (InvalidStateStoreException ignored) {
// store not yet ready for querying
                System.out.println("system is waitng to ready for state store");
                Thread.sleep(100);
                //streams.close();
            }
        }
}

}

I need to retrieve the data that i stored in state store,

what am trying to do is, need store it in local and retrievestrong text

回答1:

In your case the local KafkaStreams instance is not yet ready and thus its local state stores cannot be queried yet.

Before querying you should wait for KafkaStreams to be in RUNNING status. You need call you waitUntilStoreIsQueryable(...).

Example can be found in Confluent github:

• waitUntilStoreIsQueryable(...) definition

• usage of waitUntilStoreIsQueryable(...)

More details regarding cause can be found here: https://docs.confluent.io/current/streams/faq.html#handling-invalidstatestoreexception-the-state-store-may-have-migrated-to-another-instance

来源：https://stackoverflow.com/questions/55499553/state-store-may-have-migrated-to-another-instance