Java 获取 Kafka 指定 topic 的消息总量

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Kafka Consumer API

Kafka 提供了两套 API 给 Consumer

  • The high-level Consumer API
  • The SimpleConsumer API

第一种高度抽象的 Consumer API，它使用起来简单、方便，但是对于某些特殊的需求我们可能要用到第二种更底层的 API。

SimpleConsumer 优势

那么第二种 The SimpleConsumer API 能够帮助我们做哪些事情？

  • 一个消息读取多次
  • 在一个处理过程中只消费 Partition 其中的一部分消息
  • 添加事务管理机制以保证消息被处理且仅被处理一次

SimpleConsumer 弊端

使用 SimpleConsumer 有哪些弊端呢？

  • 必须在程序中跟踪 offset 值
  • 必须找出指定 Topic Partition 中的 lead broker
  • 必须处理 broker 的变动

SimpleConsumer 步骤

使用 SimpleConsumer 的步骤

  1. 从所有活跃的 broker 中找出哪个是指定 Topic Partition 中的 leader broker
  2. 找出指定 Topic Partition 中的所有备份 broker
  3. 构造请求
  4. 发送请求查询数据
  5. 处理 leader broker 变更

命令行获取 topic 信息总量

$ bin/kafka-run-class.sh kafka.tools.GetOffsetShell --broker-list XXX1:9092 --topic topicName1 --time -1
topicName1:2:73454
topicName1:5:73006
topicName1:4:73511
topicName1:1:73493
topicName1:3:73019
topicName1:0:72983

$ bin/kafka-run-class.sh kafka.tools.GetOffsetShell --broker-list XXX1:9092 --topic topicName1 --time -2
topicName1:2:0
topicName1:5:0
topicName1:4:0
topicName1:1:0
topicName1:3:0
topicName1:0:0

--time -1 表示要获取指定 topic 所有分区当前的最大位移，**--time -2** 表示获取当前最早位移。

两个命令的输出结果相减便可得到所有分区当前的消息总数。

分区当前的消息总数 = [--time-1] - [--time-2]

相减是因为随着 kafka 的运行，topic 中有的消息可能会被删除，因此 --time -1 的结果其实表示的是历史上该 topic 生产的最大消息数，如果用户要统计当前的消息总数就必须减去 --time -2 的结果。

本例中没有任何消息被删除，故 --time -2 的结果全是 0，表示最早位移都是 0，消息总数等于历史上发送的消息总数。

Java 获取 topic 消息总量

high-level Consumer

The high-level Consumer API 获取 Kafka 指定 topic 的消息总量：

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Properties;
import java.util.stream.Collectors;

import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.TopicPartition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class KafkaOffsetTools {
	private final static Logger logger = LoggerFactory.getLogger(KafkaOffsetTools.class);

	public static final String KAFKA_BOOTSTRAP_SERVERS = "XXX1:9092,XXX2:9092,XXX3:9092";
	public static final List<String> TOPIC_LIST = Arrays.asList("topicName1","topicName2");
	
	public static void main(String[] args) {
		for(String topic: TOPIC_LIST) {
			long totolNum = totalMessageCount(topic, KAFKA_BOOTSTRAP_SERVERS);
			System.out.println(topic+":"+totolNum);
		}
	}
	
    public static long totalMessageCount(String topic, String brokerList) {
        Properties props = new Properties();
        props.put("bootstrap.servers", brokerList);
        props.put("group.id", "test-group");
        props.put("enable.auto.commit", "false");
        props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");

        try (KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props)) {
            List<TopicPartition> tps = Optional.ofNullable(consumer.partitionsFor(topic))
                    .orElse(Collections.emptyList())
                    .stream()
                    .map(info -> new TopicPartition(info.topic(), info.partition()))
                    .collect(Collectors.toList());
            Map<TopicPartition, Long> beginOffsets = consumer.beginningOffsets(tps);
            Map<TopicPartition, Long> endOffsets = consumer.endOffsets(tps);
 
            return tps.stream().mapToLong(tp -> endOffsets.get(tp) - beginOffsets.get(tp)).sum();
        }
    }
}

输出结果：

topicName1:5301171
topicName2:439466

SimpleConsumer

The SimpleConsumer API 获取 Kafka 指定 topic 的消息总量：

import java.util.Arrays;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.TreeMap;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import kafka.api.PartitionOffsetRequestInfo;
import kafka.common.TopicAndPartition;
import kafka.javaapi.OffsetRequest;
import kafka.javaapi.OffsetResponse;
import kafka.javaapi.PartitionMetadata;
import kafka.javaapi.TopicMetadata;
import kafka.javaapi.TopicMetadataRequest;
import kafka.javaapi.TopicMetadataResponse;
import kafka.javaapi.consumer.SimpleConsumer;

public class KafkaOffsetTools {
    
	private final static Logger logger = LoggerFactory.getLogger(KafkaOffsetTools.class);

	public static final String KAFKA_BOOTSTRAP_SERVERS = "XXX1:9092,XXX2:9092,XXX3:9092";
	public static final List<String> TOPIC_LIST = Arrays.asList("topicName1","topicName2");
	
	public static void main(String[] args) {
		String[] kafkaHosts = KAFKA_BOOTSTRAP_SERVERS.split(",");
		List<String> seeds = Arrays.asList(kafkaHosts);
		KafkaOffsetTools kot = new KafkaOffsetTools();
		Map<String, Integer> topicNumMap = new HashMap<String, Integer>();
		for (String topicName : TOPIC_LIST) {
			TreeMap<Integer, PartitionMetadata> metadatas = kot.findLeader(seeds, topicName);
			int logSize = 0;
			for (Entry<Integer, PartitionMetadata> entry : metadatas.entrySet()) {
				int partition = entry.getKey();
				String leadBroker = entry.getValue().leader().host();
				String clientName = "Client_" + topicName + "_" + partition;
				SimpleConsumer consumer = new SimpleConsumer(leadBroker, entry.getValue().leader().port(), 100000, 64 * 1024, clientName);
				long readOffset = getLastOffset(consumer, topicName, partition, kafka.api.OffsetRequest.LatestTime(), clientName);
				logSize += readOffset;
				if (consumer != null) {
					consumer.close();
				}
			}
			topicNumMap.put(topicName, logSize);
		}
		System.out.println(topicNumMap.toString());
	}

	private TreeMap<Integer, PartitionMetadata> findLeader(List<String> a_seedBrokers, String a_topic) {
		TreeMap<Integer, PartitionMetadata> map = new TreeMap<Integer, PartitionMetadata>();
		for (String seed : a_seedBrokers) {
			SimpleConsumer consumer = null;
			try {
				String[] hostAndPort = seed.split(":");
				consumer = new SimpleConsumer(hostAndPort[0], Integer.valueOf(hostAndPort[1]), 100000, 64 * 1024, "leaderLookup" + new Date().getTime());
				List<String> topics = Collections.singletonList(a_topic);
				TopicMetadataRequest req = new TopicMetadataRequest(topics);
				TopicMetadataResponse resp = consumer.send(req);

				List<TopicMetadata> metaData = resp.topicsMetadata();
				for (TopicMetadata item : metaData) {
					for (PartitionMetadata part : item.partitionsMetadata()) {
						map.put(part.partitionId(), part);
					}
				}
			} catch (Throwable e) {
				logger.error("Broker [" + seed + "] to find Leader for [" + a_topic + "] Reason: " + e.getMessage(), e);
			} finally {
				if (consumer != null) {
					consumer.close();
				}
			}
		}
		return map;
	}
	
	public static long getLastOffset(SimpleConsumer consumer, String topic, int partition, long whichTime,
			String clientName) {
		TopicAndPartition topicAndPartition = new TopicAndPartition(topic, partition);
		Map<TopicAndPartition, PartitionOffsetRequestInfo> requestInfo = new HashMap<TopicAndPartition, PartitionOffsetRequestInfo>();
		requestInfo.put(topicAndPartition, new PartitionOffsetRequestInfo(whichTime, 1));
		OffsetRequest request = new kafka.javaapi.OffsetRequest(requestInfo, kafka.api.OffsetRequest.CurrentVersion(), clientName);
		OffsetResponse response = consumer.getOffsetsBefore(request);

		if (response.hasError()) {
			logger.error("Error fetching data Offset Data the Broker. Reason: " + response.errorCode(topic, partition));
			return 0;
		}
		long[] offsets = response.offsets(topic, partition);
		return offsets[0];
	}
}

输出结果：

{topicName1=5301171, topicName2=439466}
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