Kafka 4：多线程下的生产者

KafkaProducer 的实现是线程安全的，所以我们可以在多线程的环境下，安全的使用 KafkaProducer 的实例。

1.创建主题concurrent-test

./kafka-topics.sh --zookeeper localhost:2181 --create --topic concurrent-test --replication-factor 1 --partitions 8

2.添加常量

package org.example.config;

public class BusiConst {
    public static final String HELLO_TOPIC  = "hello-kafka";
    public static final String CONCURRENT_TOPIC  = "concurrent-test";
    public static final int CONCURRENT_PARTITION_COUNT = 2;
}

3.创建生产者KafkaConProducer

package org.example.concurrent;

import org.apache.kafka.clients.producer.*;
import org.apache.kafka.common.serialization.StringSerializer;
import org.example.config.BusiConst;

import java.util.Properties;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * 多线程下生产者
 **/
public class KafkaConProducer {
    //发送消息个数
    private static final int MSG_SIZE = 1000;
    //负责发送消息的线程池
    private static ExecutorService executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
    private static CountDownLatch countDownLatch = new CountDownLatch(MSG_SIZE);

    private static class ProducerWorker implements Runnable {
        private ProducerRecord<String, String> record;
        private KafkaProducer<String, String> producer;

        public ProducerWorker(ProducerRecord<String, String> record, KafkaProducer<String, String> producer) {
            this.record = record;
            this.producer = producer;
        }
        @Override
        public void run() {
            final String id = Thread.currentThread().getId() + "-" + System.identityHashCode(producer);
            try {
                producer.send(record, new Callback() {
                    @Override
                    public void onCompletion(RecordMetadata recordMetadata, Exception e) {
                        if (e != null) {
                            e.printStackTrace();
                        }
                        if (recordMetadata != null) {
                            System.out.println("offset:" + recordMetadata.offset() + ";partition:" + recordMetadata.partition());
                        }
                    }
                });
                System.out.println(id + "：数据[" + record + "]已发送。");
                countDownLatch.countDown();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args)  {
        Properties properties = new Properties();
        properties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.42.111:9092");
        properties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        properties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        KafkaProducer<String, String> producer = new KafkaProducer<>(properties);
        try {
            for (int i = 0; i < MSG_SIZE; i++) {
                ProducerRecord<String, String> record = new ProducerRecord<String, String>(
                        BusiConst.CONCURRENT_TOPIC, null, System.currentTimeMillis(), String.valueOf(i), "Fisher" + i);
                executorService.submit(new ProducerWorker(record, producer));
            }
            countDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            producer.close();
            executorService.shutdown();
        }
    }
}

4.创建消费者KafkaConConsumer，为了保证线程安全， 使用KafkaConsumer的实例要小心，应该每个消费数据的线程拥有自己的KafkaConsumer实例

package org.example.concurrent;

import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.example.config.BusiConst;

import java.time.Duration;
import java.util.Collections;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * 多线程下使用消费者，需要一个线程一个消费者
 **/
public class KafkaConConsumer {
    private static ExecutorService executorService = Executors.newFixedThreadPool(BusiConst.CONCURRENT_PARTITION_COUNT);
    private static class ConsumerWorker implements Runnable{
        private KafkaConsumer<String, String> consumer;
		//使用KafkaConsumer的实例要小心，应该每个消费数据的线程拥有自己的KafkaConsumer实例
        public ConsumerWorker(Properties properties, String topic) {
            this.consumer = new KafkaConsumer<String, String>(properties);
            consumer.subscribe(Collections.singletonList(topic));
        }
        @Override
        public void run() {
            final String id = Thread.currentThread().getId() + "-" + System.identityHashCode(consumer);
            try {
                while (true) {
                    ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(5000));
                    for (ConsumerRecord record : records) {
                        System.out.println("do something");
                        System.out.println(id+"|主题"+record.topic()+"，分区"+record.partition()+
                                "，偏移量"+record.offset()+"，key:"+record.key()+"，value:"+record.value());
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                consumer.close();
            }
        }
    }

    public static void main(String[] args) {
        Properties properties = new Properties();
        properties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.42.111:9092");
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        properties.put(ConsumerConfig.GROUP_ID_CONFIG, "concurrent");
        for (int i = 0; i < BusiConst.CONCURRENT_PARTITION_COUNT; i++) {
            executorService.submit(new ConsumerWorker(properties, BusiConst.CONCURRENT_TOPIC));
        }
    }
}

5.先启动消费者，再启动生产者

6.查看消费者打印

最后

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