Java API获取topic所占磁盘空间(Kafka 1.0.0)

很多用户都有这样的需求：实时监控某个topic各分区在broker上所占的磁盘空间大小总和。Kafka并没有提供直接的脚本工具用于统计这些数据。

如果依然要实现这个需求，一种方法是通过监控JMX指标得到分区当前总的日志大小，然后手动相加所有分区的值得出；另一种方法就是使用1.0.0引入的DescribeLogDirsRequest请求。本文即介绍如何通过Java API获取某broker上某topic总的空间大小，代码如下：

package huxihx;

import org.apache.kafka.clients.admin.AdminClient;
import org.apache.kafka.clients.admin.AdminClientConfig;
import org.apache.kafka.clients.admin.DescribeLogDirsResult;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.requests.DescribeLogDirsResponse;

import java.util.Collections;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ExecutionException;

public class TopicDiskSizeSummary {

    private static AdminClient admin;

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        String brokers = "localhost:9092";
        initialize(brokers);
        try {
            long topic1InBroker1 = getTopicDiskSizeForSomeBroker("t2", 1);
            long topic2InBroker0 = getTopicDiskSizeForSomeBroker("t1", 0);
            System.out.println(topic1InBroker1);
            System.out.println(topic2InBroker0);
        } finally {
            shutdown();
        }
    }

    public static long getTopicDiskSizeForSomeBroker(String topic, int brokerID)
            throws ExecutionException, InterruptedException {
        long sum = 0;
        DescribeLogDirsResult ret = admin.describeLogDirs(Collections.singletonList(brokerID));
        Map<Integer, Map<String, DescribeLogDirsResponse.LogDirInfo>> tmp = ret.all().get();
        for (Map.Entry<Integer, Map<String, DescribeLogDirsResponse.LogDirInfo>> entry : tmp.entrySet()) {
            Map<String, DescribeLogDirsResponse.LogDirInfo> tmp1 = entry.getValue();
            for (Map.Entry<String, DescribeLogDirsResponse.LogDirInfo> entry1 : tmp1.entrySet()) {
                DescribeLogDirsResponse.LogDirInfo info = entry1.getValue();
                Map<TopicPartition, DescribeLogDirsResponse.ReplicaInfo> replicaInfoMap = info.replicaInfos;
                for (Map.Entry<TopicPartition, DescribeLogDirsResponse.ReplicaInfo> replicas : replicaInfoMap.entrySet()) {
                    if (topic.equals(replicas.getKey().topic())) {
                        sum += replicas.getValue().size;
                    }
                }
            }
        }
        return sum;
    }

    private static void initialize(String bootstrapServers) {
        Properties props = new Properties();
        props.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        admin = AdminClient.create(props);
    }

    private static void shutdown() {
        if (admin != null) {
            admin.close();
        }
    }
}

其中主要的方法是AdminClient.describeLogDirs()，它返回DescribeLogDirsResult实例，里面封装了给定broker上所有log.dirs路径下对应的分区的日志大小，将它们加到一起即可实现统计topic磁盘空间占用的功能。