提交 jar 文件时，控制台中未打印来自 Kafka 的数据。 （Spark 流 + Kafka 集成 3.1.1）

Question

There is no error when I submitted a jar file.

But data isn't printed when I send data using the HTTP protocol.

(Data is printed well when I check using "kafka-console-consumer.sh" )

[Picture, submitted a jar file: Data isn't printed]

code and dependencies in jar files are down below.

[Picture, Kafka-console-consumer.sh: Data is printed]

command:

bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --group test-consumer --topic test01 --from-beginning

[JAVA FILE]

2-1, Dependencies

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
        <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>org.apache.spark</groupId>
      <artifactId>spark-core_2.12</artifactId>
      <version>3.1.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.spark</groupId>
        <artifactId>spark-streaming_2.12</artifactId>
        <version>3.1.1</version>
        <scope>provided</scope>
    </dependency>
    
    <dependency>
        <groupId>org.apache.spark</groupId>
        <artifactId>spark-streaming-kafka-0-10_2.12</artifactId>
        <version>3.1.1</version>
    </dependency>
</dependencies>

2-2, Code

package SparkTest.SparkStreaming;

import org.apache.spark.streaming.*;
import org.apache.spark.streaming.api.java.*;
import java.util.*;
import org.apache.spark.SparkConf;
import org.apache.spark.streaming.kafka010.*;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.common.serialization.StringDeserializer;


public final class JavaWordCount {
    public static void main(String[] args) throws Exception {
        // Create a local StreamingContext with two working thread and batch interval of 1 second
        SparkConf conf = new SparkConf().setMaster("yarn").setAppName("JavaWordCount");
        JavaStreamingContext jssc = new JavaStreamingContext(conf, Durations.seconds(1));
        
        // load a topic from broker
        Map<String, Object> kafkaParams = new HashMap<>();
        kafkaParams.put("bootstrap.servers", "localhost:9092");
        kafkaParams.put("key.deserializer", StringDeserializer.class);
        kafkaParams.put("value.deserializer", StringDeserializer.class);
        kafkaParams.put("group.id", "test-consumer");
        kafkaParams.put("auto.offset.reset", "latest");
        kafkaParams.put("enable.auto.commit", false);

        Collection<String> topics = Arrays.asList("test01");

        JavaInputDStream<ConsumerRecord<String, String>> stream =
          KafkaUtils.createDirectStream(
            jssc,
            LocationStrategies.PreferBrokers(),
            ConsumerStrategies.<String, String>Subscribe(topics, kafkaParams)
          );
        
        JavaDStream<String> data = stream.map(v -> {
            return v.value();    // mapping to convert into spark D-Stream 
        });
      
        data.print();
        
        jssc.start();
        jssc.awaitTermination();
    }
}

Answer 1

You're using --from-beginning in the console consumer, but auto.offset.reset=latest in the Spark code.

Therefore, you need to run the producer while Spark runs if you want to see any data

You will also want to consider using spark-sql-kafka-0-10 Structured Streaming dependency instead, as you can find in the KafkaWordCount example