背景

監(jiān)控是Spark非常重要的一部分。Spark的運(yùn)行情況是由ListenerBus以及MetricsSystem 來完成的。通過Spark的Metrics系統(tǒng)，我們可以把Spark Metrics的收集到的信息發(fā)送到各種各樣的Sink，比如HTTP、JMX以及CSV文件。
目前支持的Sink包括：

• ConsoleSink
• CSVSink
• JmxSink
• MetricsServlet
• GraphiteSink
• GangliaSink

有時(shí)我們需要實(shí)時(shí)獲取metrics數(shù)據(jù)通過spark分析展示等需求，這個(gè)時(shí)候若有個(gè)KafkaSink將metrics指標(biāo)數(shù)據(jù)實(shí)時(shí)往kafka發(fā)送那就太方便了，故有了這篇博文。

實(shí)踐

所有的Sink都需要繼承Sink這個(gè)特質(zhì)：

private[spark] trait Sink {
  def start(): Unit
  def stop(): Unit
  def report(): Unit
}

當(dāng)該Sink注冊到metrics系統(tǒng)中時(shí)，會調(diào)用start方法進(jìn)行一些初始化操作，再通過report方式進(jìn)行真正的輸出操作，stop方法可以進(jìn)行一些連接關(guān)閉等操作。直接上代碼：

package org.apache.spark.metrics.sink

import java.util.concurrent.TimeUnit
import java.util.{Locale, Properties}

import com.codahale.metrics.MetricRegistry
import org.apache.kafka.clients.producer.KafkaProducer
import org.apache.spark.SecurityManager
import org.apache.spark.internal.Logging

private[spark] class KafkaSink(val property: Properties, val registry: MetricRegistry,
                               securityMgr: SecurityManager) extends Sink with Logging{

    val KAFKA_KEY_PERIOD = "period"
    val KAFKA_DEFAULT_PERIOD = 10

    val KAFKA_KEY_UNIT = "unit"
    val KAFKA_DEFAULT_UNIT = "SECONDS"

    val KAFKA_TOPIC = "topic"
    val KAFKA_DEFAULT_TOPIC = "kafka-sink-topic"

    val KAFAK_BROKERS = "kafka-brokers"
    val KAFAK_DEFAULT_BROKERS = "XXX:9092"

    val TOPIC = Option(property.getProperty(KAFKA_TOPIC)).getOrElse(KAFKA_DEFAULT_TOPIC)
    val BROKERS = Option(property.getProperty(KAFAK_BROKERS)).getOrElse(throw new IllegalStateException("kafka-brokers is null!"))

    private val kafkaProducerConfig = new Properties()
    kafkaProducerConfig.put("bootstrap.servers",BROKERS)
    kafkaProducerConfig.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer")
    kafkaProducerConfig.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer")

    private val producer = new KafkaProducer[String, String](kafkaProducerConfig)

    private val reporter: KafkaReporter = KafkaReporter.forRegistry(registry)
        .topic(TOPIC)
        .build(producer)


    val pollPeriod = Option(property.getProperty(KAFKA_KEY_PERIOD)) match {
        case Some(s) => s.toInt
        case None => KAFKA_DEFAULT_PERIOD
    }

    val pollUnit: TimeUnit = Option(property.getProperty(KAFKA_KEY_UNIT)) match {
        case Some(s) => TimeUnit.valueOf(s.toUpperCase(Locale.ROOT))
        case None => TimeUnit.valueOf(KAFKA_DEFAULT_UNIT)
    }

    override def start(): Unit = {
        log.info("I4 Metrics System KafkaSink Start ......")
        reporter.start(pollPeriod, pollUnit)
    }

    override def stop(): Unit = {
        log.info("I4 Metrics System KafkaSink Stop ......")
        reporter.stop()
        producer.close()
    }

    override def report(): Unit = {
        log.info("I4 Metrics System KafkaSink Report ......")
        reporter.report()
    }
}

KafkaReporter類：

package org.apache.spark.metrics.sink;

import com.alibaba.fastjson.JSONObject;
import com.codahale.metrics.*;
import com.twitter.bijection.Injection;
import com.twitter.bijection.avro.GenericAvroCodecs;
import org.apache.avro.Schema;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Map;
import java.util.SortedMap;
import java.util.concurrent.TimeUnit;

public class KafkaReporter  extends ScheduledReporter  {

    private static final Logger LOGGER = LoggerFactory.getLogger(KafkaReporter.class);

    public static KafkaReporter.Builder forRegistry(MetricRegistry registry) {
        return new KafkaReporter.Builder(registry);
    }

    private KafkaProducer producer;
    private Clock clock;
    private String topic;

    private KafkaReporter(MetricRegistry registry,
                        TimeUnit rateUnit,
                        TimeUnit durationUnit,
                        MetricFilter filter,
                        Clock clock,
                        String topic,
                        KafkaProducer producer) {
        super(registry, "kafka-reporter", filter, rateUnit, durationUnit);
        this.producer = producer;
        this.topic = topic;
        this.clock = clock;
    }

    @Override
    public void report(SortedMap<String, Gauge> gauges, SortedMap<String, Counter> counters, SortedMap<String, Histogram> histograms, SortedMap<String, Meter> meters, SortedMap<String, Timer> timers) {
        final long timestamp = TimeUnit.MILLISECONDS.toSeconds(clock.getTime());

        // Gauge
        for (Map.Entry<String, Gauge> entry : gauges.entrySet()) {
            reportGauge(timestamp,entry.getKey(), entry.getValue());
        }
        // Histogram
//        for (Map.Entry<String, Histogram> entry : histograms.entrySet()) {
//            reportHistogram(timestamp, entry.getKey(), entry.getValue());
//        }
    }


    private void reportGauge(long timestamp, String name, Gauge gauge) {
        report(timestamp, name, gauge.getValue());
    }

    private void reportHistogram(long timestamp, String name, Histogram histogram) {
        final Snapshot snapshot = histogram.getSnapshot();
        report(timestamp, name, snapshot.getMax());
    }

    private void report(long timestamp, String name,  Object values) {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("name",name);
        jsonObject.put("timestamp",timestamp);
        jsonObject.put("value",values);
        producer.send(new ProducerRecord(topic,name, jsonObject.toJSONString()));
    }


    public static class Builder {

        private final MetricRegistry registry;
        private TimeUnit rateUnit;
        private TimeUnit durationUnit;
        private MetricFilter filter;
        private Clock clock;
        private String topic;

        private Builder(MetricRegistry registry) {
            this.registry = registry;
            this.rateUnit = TimeUnit.SECONDS;
            this.durationUnit = TimeUnit.MILLISECONDS;
            this.filter = MetricFilter.ALL;
            this.clock = Clock.defaultClock();
        }

        /**
         * Convert rates to the given time unit.
         *
         * @param rateUnit a unit of time
         * @return {@code this}
         */
        public KafkaReporter.Builder convertRatesTo(TimeUnit rateUnit) {
            this.rateUnit = rateUnit;
            return this;
        }

        /**
         * Convert durations to the given time unit.
         *
         * @param durationUnit a unit of time
         * @return {@code this}
         */
        public KafkaReporter.Builder convertDurationsTo(TimeUnit durationUnit) {
            this.durationUnit = durationUnit;
            return this;
        }

        /**
         * Use the given {@link Clock} instance for the time.
         *
         * @param clock a {@link Clock} instance
         * @return {@code this}
         */
        public Builder withClock(Clock clock) {
            this.clock = clock;
            return this;
        }

        /**
         * Only report metrics which match the given filter.
         *
         * @param filter a {@link MetricFilter}
         * @return {@code this}
         */
        public KafkaReporter.Builder filter(MetricFilter filter) {
            this.filter = filter;
            return this;
        }

        /**
         * Only report metrics which match the given filter.
         *
         * @param topic a
         * @return {@code this}
         */
        public KafkaReporter.Builder topic(String topic) {
            this.topic = topic;
            return this;
        }

        /**
         * Builds a {@link KafkaReporter} with the given properties, writing {@code .csv} files to the
         * given directory.
         *
         * @return a {@link KafkaReporter}
         */
        public KafkaReporter build(KafkaProducer producer) {
            return new KafkaReporter(registry,
                    rateUnit,
                    durationUnit,
                    filter,
                    clock,
                    topic,
                    producer);
        }
    }
}

其中的report方法就是獲取各種類型指標(biāo)，并進(jìn)行對應(yīng)的輸出操作的時(shí)機(jī)。

如何使用

可在配置文件或者程序中設(shè)定需要注冊的sink，并帶上對應(yīng)的參數(shù)即可：

spark.metrics.conf.*.sink.kafka.class=org.apache.spark.metrics.sink.KafkaSink
spark.metrics.conf.*.sink.kafka.kafka-brokers=XXX:9092

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