Error in my Kafka custom partitioner class

Question

I am working on a Kafka Custom partitioner class. Here I am trying to push the data into separate partitions. My Kafka producer class:

import java.util.Date;
import java.util.Properties;
import java.util.Random;

import kafka.javaapi.producer.Producer;
import kafka.producer.KeyedMessage;
import kafka.producer.ProducerConfig;

public class KafkaCustomPartitioner {
    public static void main(String[] args) {
        long events = Long.parseLong(args[0]);
        int  blocks = Integer.parseInt(args[1]);
        Random  rnd = new Random();

        Properties props = new Properties();
        props.put("metadata.broker.list", "localhost:9092");
        props.put("serializer.class","kafka.serializer.StringEncoder");
        props.put("key.serializer.class", "kafka.serializer.StringEncoder");
        props.put("partitioner.class","com.kafka.partdecider.CustomPartitioner");
        props.put("producer.type", "sync");
        props.put("request.required.acks","1");

        ProducerConfig config = new ProducerConfig(props);
        Producer producer = new Producer(config);

        for(int nBlocks=0; nBlocks<blocks; nBlocks++) {
            for(long nEvents=0; nEvents<events; nEvents++) {
                long runTime = new Date().getTime();
                String msg   = runTime + ": " + (50+nBlocks) + ": " + nEvents + ": " + rnd;
                KeyedMessage<String, String> data = new KeyedMessage<String, String>("CustPartTopic",String.valueOf(nBlocks),msg);
                producer.send(data);
            }
        }
        producer.close();
    }
}

Customer Partitioner Class:

import kafka.producer.Partitioner;

public class CustomPartitioner implements Partitioner {

    public int partition(Object key, int arg1) {
        String receivingkey = (String) key;
        long id = Long.parseLong(receivingkey);
        return (int) (id%arg1);
    }
}

The project's arguments section has the values: 3 2 I am getting "ArrayOutOfBoundsException" at this line if I run the class:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
    at com.kafka.custompartitioner.KafkaCustomPartitioner.main(KafkaCustomPartitioner.java:13)

The error is shown at the line: long events = Long.parseLong(args[0]); But I don't understand why is that line giving the error. Could anyone let me know how can I fix this ?

Answer 1

This works for me, the API are quite different :

package mypackage.io;

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;

import java.util.Date;
import java.util.Properties;
import java.util.Random;
import java.util.concurrent.ExecutionException;

public class KafkaCustomPartitioner {

public static void main(String[] args) throws InterruptedException, ExecutionException {

    long events = Long.parseLong(args[0]);
    int  blocks = Integer.parseInt(args[1]);
    Random rnd = new Random();

    Properties props = new Properties();
    props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
    props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
    props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
    props.put(ProducerConfig.PARTITIONER_CLASS_CONFIG, "mypackage.io.CustomPartitioner");
    props.put(ProducerConfig.ACKS_CONFIG, "1");

    KafkaProducer<String, String> producer = new KafkaProducer<String, String>(props);

    for(int nBlocks=0; nBlocks<blocks; nBlocks++) {

        for(long nEvents=0; nEvents<events; nEvents++) {

            long runTime = new Date().getTime();
            String msg   = runTime + ": " + (50+nBlocks) + ": " + nEvents + ": " + rnd;
            producer.send(new ProducerRecord<String, String>("CustPartTopic", String.valueOf(nBlocks), msg)).get();
        }
    }
    producer.close();
    }
 }

then the custom partitioner

package mypackage.io;

import org.apache.kafka.clients.producer.Partitioner;
import org.apache.kafka.common.Cluster;

import java.util.Map;

public class CustomPartitioner implements Partitioner {

public int partition(String topic, Object key, byte[] keyBytes, Object value, byte[] valueBytes, Cluster cluster) {

    String receivingkey = (String) key;
    long id = Long.parseLong(receivingkey);
    int numPartitions = cluster.availablePartitionsForTopic(topic).size();
    return (int) (id % numPartitions);
}

public void close() {

}

public void configure(Map<String, ?> map) {

}
}