Spark整合kafka0.10.0新特性（一）

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Spark整合kafka0.10.0新特性(一)

Spark Streaming + Kafka Integration Guide (Kafka broker version 0.10.0 or higher)整合kafka0.10.0新特性（API都在实验中）。

The Spark Streaming integration for Kafka 0.10和kafka0.8的Direct Stream approach非常相似，并行度Kafka分区和Spark分区的比例1:1，并且可以访问Kafka的偏移和元数据。然而，新的整合方案使用的是new Kafka consumer API 而不是 simple API，所以在使用过程中需要注意区别，这个版本的整合现在正处于experimental，因此API可能随着时间会有变化。 Linking

For Scala/Java applications using SBT/Maven project definitions, link your streaming application with the following artifact (see Linking sectionin the main programming guide for further information).

groupId = org.apache.spark

artifactId = spark-streaming-kafka-0-10_2.11 version = 2.1.0

无论使用sbt还是maven，都需引入上面的坐标。

Creating a Direct Stream

注意导入包的路径是org.apache.spark.streaming.kafka010，切勿倒错包。

import org.apache.kafka.clients.consumer.ConsumerRecord import org.apache.kafka.common.serialization.StringDeserializer import org.apache.spark.streaming.kafka010._

import org.apache.spark.streaming.kafka010.LocationStrategies.PreferConsistent import org.apache.spark.streaming.kafka010.ConsumerStrategies.Subscribe

val kafkaParams = Map[String, Object](

\ \ \

\ \

val topics = Array(\

val stream = KafkaUtils.createDirectStream[String, String](

streamingContext,//create entry point for all streaming functionality

PreferConsistent,//important feature：preferConsistent是一个方法，是consumer调度分区的位置策略

Subscribe[String, String](topics, kafkaParams)//is also import feature ：Subscribe是consumer的消费策略

)

stream.map(record => (record.key, record.value))

重点解释一下 PreferConsistent方法，首先我们还是看一下PreferConsistent方法实现，源码如下：

[java] view plain copy 在CODE上查看代码片派生到我的代码片 package org.apache.spark.streaming.kafka010

import java.{util => ju}

import scala.collection.JavaConverters._

import org.apache.kafka.common.TopicPartition import org.apache.spark.annotation.Experimental

import org.apache.spark.streaming.kafka010.{LocationStrategies, LocationStrategy, PreferFixed} /**

* :: Experimental ::

* Choice of how to schedule consumers for a given TopicPartition on an executor. * See [[LocationStrategies]] to obtain instances.

* Kafka 0.10 consumers prefetch messages, so it's important for performance

* to keep cached consumers on appropriate executors, not recreate them for every partition. * Choice of location is only a preference, not an absolute; partitions may be scheduled elsewhere. * 实验性API:

* 在executor上consumer如何调度给定的TopicPartition，使用LocationStrategies获取调度策略实例

* Kafka 0.10的消费者可以预取消息，因此对于性能来说在适合的executors上缓存

consumers是比较重要的，而不是对每一个分区

* 进行重新创建。对于分区位置的选择只是一个偏好，并非是绝对的。分区可能被调度到其他位置 * * */

@Experimental

sealed abstract class LocationStrategy

/**

* 使用PreferBrokers策略，必须是你的executors和kafka brokers在相同节点上。 */

private case object PreferBrokers extends LocationStrategy /**

* 大多数情况下使用PreferConsistent需要一贯的将kafka的分区分布到所有的executors上 */

private case object PreferConsistent extends LocationStrategy /**

* Use this to place particular TopicPartitions on particular hosts if your load is uneven.

* Any TopicPartition not specified in the map will use a consistent location.

* 默认情况如果分区加载的不均衡的话，可以使用这个策略：放置特定的分区到特定的主机上

* 任何TopicPartition没有和hosts映射的TopicPartition将会使用consistent location（就是安置到所有executor） *

* 参数Map：就是TopicPartition和主机地址的映射 */

private case class PreferFixed(hostMap: ju.Map[TopicPartition, String]) extends LocationStrategy /**

* :: Experimental :: object to obtain instances of [[LocationStrategy]] * */

@Experimental

object LocationStrategies { /**

* :: Experimental ::

* Use this only if your executors are on the same nodes as your Kafka brokers. */

@Experimental

def PreferBrokers: LocationStrategy =

org.apache.spark.streaming.kafka010.PreferBrokers /**

* :: Experimental ::

* Use this in most cases, it will consistently distribute partitions across all executors. */

@Experimental

def PreferConsistent: LocationStrategy =

org.apache.spark.streaming.kafka010.PreferConsistent /**

* :: Experimental ::

* Use this to place particular TopicPartitions on particular hosts if your load is uneven.

* Any TopicPartition not specified in the map will use a consistent location.

* 两个方法就是Map类型不一样而已，一个是Scala Map 另一个是Java Map * */

@Experimental

def PreferFixed(hostMap: collection.Map[TopicPartition, String]): LocationStrategy = new PreferFixed(new ju.HashMap[TopicPartition, String](hostMap.asJava)) /**

* :: Experimental ::

* Use this to place particular TopicPartitions on particular hosts if your load is uneven. * Any TopicPartition not specified in the map will use a consistent location. */

@Experimental

def PreferFixed(hostMap: ju.Map[TopicPartition, String]): LocationStrategy = new PreferFixed(hostMap) }

接下来学习一下Subscribe，上面Subscribe是伴生对象ConsumerStrategies的一个静态方法，ConsumerStrategies可以说是consumer消费策略的一个工厂。

接下来看一下 ConsumerStrategy，重点部门见源码注释，源码如下：

[java] view plain copy 在CODE上查看代码片派生到我的代码片 package org.apache.spark.streaming.kafka010

import java.{ lang => jl, util => ju }

import scala.collection.JavaConverters._

import org.apache.kafka.clients.consumer._

import org.apache.kafka.clients.consumer.internals.NoOpConsumerRebalanceListener import org.apache.kafka.common.TopicPartition

import org.apache.spark.annotation.Experimental import org.apache.spark.internal.Logging

/**

* :: Experimental ::

* Choice of how to create and configure underlying Kafka Consumers on driver and executors. * See [[ConsumerStrategies]] to obtain instances.

* Kafka 0.10 consumers can require additional, sometimes complex, setup after object * instantiation. This interface encapsulates that process, and allows it to be checkpointed. * @tparam K type of Kafka message key * @tparam V type of Kafka message value *

* 选择如何创建和配置在Driver和Executor上的Kafka Consumer实例，使用ConsumerStrategies获取策略实例

* Kafka 0.10 consumers 在对象被实例化之后需要额外的配置，有时候比较复杂，这个接口封装了那些过程

* 并允许实例被checkpointed * */

@Experimental

abstract class ConsumerStrategy[K, V] { /**

* Kafka

* configuration parameters to be used on executors. Requires \set

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

*配置参数会在executors上被使用，需要设置bootstrap.servers指定Kafka的broker的主机和端口 * */

def executorKafkaParams: ju.Map[String, Object] /**

* Must return a fully configured Kafka Consumer, including subscribed or assigned topics. * See .

* This consumer will be used on the driver to query for offsets only, not messages. * The consumer must be returned in a state that it is safe to call poll(0) on.

* @param currentOffsets A map from TopicPartition to offset, indicating how far the driver * has successfully read. Will be empty on initial start, possibly non-empty on restart from * checkpoint.

*返回一个必须是fully配置的Kafka Consumer，消费策略可以是subscribed或者assigned * consumer将会在driver上使用查询偏移而不是查询消息 * 返回的consumer状态必须是安全的调用poll(0)方法

* currentOffsets参数是一个TopicPartition到offset的映射map，可以标示：

* driver已经成功读取多少信息，第一次启动时候可能是empty，在checkpoint中restart

不为空 * */

def onStart(currentOffsets: ju.Map[TopicPartition, jl.Long]): Consumer[K, V] } /**

* Subscribe to a collection of topics.

* @param topics collection of topics to subscribe * @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. *

* 订阅一组topic消息 *kafkaParams参数：

*配置参数将会在driver上使用，并且相同参数也会发送到executor上使用，在executor上可能略微的配置修改

*通知需要设置bootstrap.servers指定broker *

*offsets参数：

* offsets伴随着startup开始,如果对于TopicPartition没有指定offset， * 提交的offset或auto.offset.reset将会被使用 * * */

private case class Subscribe[K, V](

topics: ju.Collection[jl.String],

kafkaParams: ju.Map[String, Object], offsets: ju.Map[TopicPartition, jl.Long]

) extends ConsumerStrategy[K, V] with Logging { /**

*继承至ConsumerStrategy的方法，获取配置参数 *

* @return */

def executorKafkaParams: ju.Map[String, Object] = kafkaParams

/** *

* 继承至ConsumerStrategy的方法,用于创建Consumer * @return */

def onStart(currentOffsets: ju.Map[TopicPartition, jl.Long]): Consumer[K, V] = { val consumer = new KafkaConsumer[K, V](kafkaParams) consumer.subscribe(topics)

val toSeek = if (currentOffsets.isEmpty) { offsets } else {

currentOffsets }

if (!toSeek.isEmpty) {

// work around KAFKA-3370 when reset is none

// poll will throw if no position, i.e. auto offset reset none and no explicit position

// but cant seek to a position before poll, because poll is what gets subscription partitions // So, poll, suppress the first exception, then seek

val aor = kafkaParams.get(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG)

val shouldSuppress = aor != null && aor.asInstanceOf[String].toUpperCase == \ try {

consumer.poll(0) } catch {

case x: NoOffsetForPartitionException if shouldSuppress =>

logWarning(\

ConsumerConfig.AUTO_OFFSET_RESET_CONFIG + \is none. See KAFKA-3370\ }

toSeek.asScala.foreach { case (topicPartition, offset) => consumer.seek(topicPartition, offset) }

// we've called poll, we must pause or next poll may consume messages and set position consumer.pause(consumer.assignment()) }

consumer } } /**

* Subscribe to all topics matching specified pattern to get dynamically assigned partitions. * The pattern matching will be done periodically against topics existing at the time of check. * @param pattern pattern to subscribe to

* @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. *

* SubscribePattern是订阅所有匹配正则表达式模式的topic的数据

* topic模式匹配将会周期性的进行匹配，而不是在检查已存在的topic时候进行模式匹配 *

* kafkaParams参数：

*配置参数将会在driver上使用，并且相同参数也会发送到executor上使用，在executor上可能略微的配置修改

*通知需要设置bootstrap.servers指定broker *

*offsets参数：

* offsets伴随着startup开始,如果对于TopicPartition没有指定offset， * 提交的offset或auto.offset.reset将会被使用 * * */

private case class SubscribePattern[K, V](

pattern: ju.regex.Pattern,

kafkaParams: ju.Map[String, Object], offsets: ju.Map[TopicPartition, jl.Long] ) extends ConsumerStrategy[K, V] with Logging {

def executorKafkaParams: ju.Map[String, Object] = kafkaParams

def onStart(currentOffsets: ju.Map[TopicPartition, jl.Long]): Consumer[K, V] = { val consumer = new KafkaConsumer[K, V](kafkaParams)

consumer.subscribe(pattern, new NoOpConsumerRebalanceListener()) val toSeek = if (currentOffsets.isEmpty) { offsets } else {

currentOffsets }

if (!toSeek.isEmpty) {

// work around KAFKA-3370 when reset is none, see explanation in Subscribe above val aor = kafkaParams.get(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG)

val shouldSuppress = aor != null && aor.asInstanceOf[String].toUpperCase == \ try {

consumer.poll(0) } catch {

case x: NoOffsetForPartitionException if shouldSuppress =>

logWarning(\

ConsumerConfig.AUTO_OFFSET_RESET_CONFIG + \is none. See KAFKA-3370\ }

toSeek.asScala.foreach { case (topicPartition, offset) => consumer.seek(topicPartition, offset) }

// we've called poll, we must pause or next poll may consume messages and set position consumer.pause(consumer.assignment()) }

consumer } } /**

* Assign a fixed collection of TopicPartitions

* @param topicPartitions collection of TopicPartitions to assign * @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors, * with minor autowww.sm136.commatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. *

* 订阅一个固定数目的TopicPartitions * kafkaParams参数：

*配置参数将会在driver上使用，并且相同参数也会发送到executor上使用，在executor上可能略微的配置修改

*通知需要设置bootstrap.servers指定broker *

*offsets参数：

* offsets伴随着startup开始,如果对于TopicPartition没有指定offset， * 提交的offset或auto.offset.reset将会被使用 *

* * */

private case class Assign[K, V](

topicPartitions: ju.Collection[TopicPartition], kafkaParams: ju.Map[String, Object], offsets: ju.Map[TopicPartition, jl.Long] ) extends ConsumerStrategy[K, V] {

def executorKafkaParams: ju.Map[String, Object] = kafkaParams

def onStart(currentOffsets: ju.Map[TopicPartition, jl.Long]): Consumer[K, V] = { val consumer = new KafkaConsumer[K, V](kafkaParams) consumer.assign(topicPartitions)

val toSeek = if (currentOffsets.isEmpty) { offsets } else {

currentOffsets }

if (!toSeek.isEmpty) {

// this doesn't need a KAFKA-3370 workaround, because partitions are known, no poll needed

toSeek.asScala.foreach { case (topicPartition, offset) => consumer.seek(topicPartition, offset) } }

consumer } } /**

* :: Experimental ::

* object for obtaining instances of [[ConsumerStrategy]] *

* 这个是订阅策略的工厂方法：用于实例化策略的 * * * */

@Experimental

object ConsumerStrategies { /**

* :: Experimental ::

* Subscribe to a collection of topics.

* @param topics collection of topics to subscribe * @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. */

@Experimental

def Subscribe[K, V](

topics: Iterable[jl.String],

kafkaParams: collection.Map[String, Object],

offsets: collection.Map[TopicPartition, Long]): ConsumerStrategy[K, V] = {

new Subscribe[K, V](

new ju.ArrayList(topics.asJavaCollection),

new ju.HashMap[String, Object](kafkaParams.asJava),

new ju.HashMap[TopicPartition, jl.Long](offsets.mapValues(l => new jl.Long(l)).asJava)) } /**

* :: Experimental ::

* Subscribe to a collection of topics.

* @param topics collection of topics to subscribe * @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form. */

@Experimental

def Subscribe[K, V](

topics: Iterable[jl.String],

kafkaParams: collection.Map[String, Object]): ConsumerStrategy[K, V] = {

new Subscribe[K, V](

new ju.ArrayList(topics.asJavaCollection),

new ju.HashMap[String, Object](kafkaParams.asJava), ju.Collections.emptyMap[TopicPartition, jl.Long]()) } /**

* :: Experimental ::

* Subscribe to a collection of topics.

* @param topics collection of topics to subscribe * @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. */

@Experimental

def Subscribe[K, V](

topics: ju.Collection[jl.String],

kafkaParams: ju.Map[String, Object],

offsets: ju.Map[TopicPartition, jl.Long]): ConsumerStrategy[K, V] = {

new Subscribe[K, V](topics, kafkaParams, offsets) } /**

* :: Experimental ::

* Subscribe to a collection of topics.

* @param topics collection of topics to subscribe * @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form. */

@Experimental

def Subscribe[K, V](

topics: ju.Collection[jl.String],

kafkaParams: ju.Map[String, Object]): ConsumerStrategy[K, V] = { new Subscribe[K, V](topics, kafkaParams, ju.Collections.emptyMap[TopicPartition, jl.Long]())

}

/** :: Experimental ::

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. */

@Experimental

def SubscribePattern[K, V](

pattern: ju.regex.Pattern,

kafkaParams: collection.Map[String, Object], offsets: collection.Map[TopicPartition, Long]): ConsumerStrategy[K, V] = {

new SubscribePattern[K, V]( pattern,

new ju.HashMap[String, Object](kafkaParams.asJava),

new ju.HashMap[TopicPartition, jl.Long](offsets.mapValues(l => new jl.Long(l)).asJava)) }

/** :: Experimental ::

configuration parameters to be used on driver. The same params will be used on executors, * with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form. */

@Experimental

def SubscribePattern[K, V](

pattern: ju.regex.Pattern, kafkaParams: collection.Map[String, Object]): ConsumerStrategy[K, V] = {

new SubscribePattern[K, V]( pattern,

new ju.HashMap[String, Object](kafkaParams.asJava), ju.Collections.emptyMap[TopicPartition, jl.Long]()) }

/** :: Experimental ::

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. */

@Experimental

def SubscribePattern[K, V](

pattern: ju.regex.Pattern,

kafkaParams: ju.Map[String, Object], offsets: ju.Map[TopicPartition, jl.Long]): ConsumerStrategy[K, V] = {

new SubscribePattern[K, V](pattern, kafkaParams, offsets) }

/** :: Experimental ::

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form. */

@Experimental

def SubscribePattern[K, V](

pattern: ju.regex.Pattern,

kafkaParams: ju.Map[String, Object]): ConsumerStrategy[K,

V] = {

new SubscribePattern[K, V]( pattern,

kafkaParams,

ju.Collections.emptyMap[TopicPartition, jl.Long]()) } /**

* :: Experimental ::

* Assign a fixed collection of TopicPartitions

* @param topicPartitions collection of TopicPartitions to assign * @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. */

@Experimental def Assign[K, V](

topicPartitions: Iterable[TopicPartition],

kafkaParams: collection.Map[String, Object],

offsets: collection.Map[TopicPartition, Long]): ConsumerStrategy[K, V] = {

new Assign[K, V](

new ju.ArrayList(topicPartitions.asJavaCollection), new ju.HashMap[String, Object](kafkaParams.asJava),

new ju.HashMap[TopicPartition, jl.Long](offsets.mapValues(l => new jl.Long(l)).asJava)) } /**

* :: Experimental ::

* Assign a fixed collection of TopicPartitions

* @param topicPartitions collection of TopicPartitions to assign * @param kafkaParams Kwww.edu800.cnafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form. */

@Experimental def Assign[K, V](

topicPartitions: Iterable[TopicPartition],

kafkaParams: collection.Map[String, Object]): ConsumerStrategy[K, V] = {

new Assign[K, V](

new ju.ArrayList(topicPartitions.asJavaCollection), new ju.HashMap[String, Object](kafkaParams.asJava), ju.Collections.emptyMap[TopicPartition, jl.Long]()) } /**

* :: Experimental ::

* Assign a fixed collection of TopicPartitions

* @param topicPartitions collection of TopicPartitions to assign * @param kafkaParams Kafka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form.

* @param offsets: offsets to begin at on initial startup. If no offset is given for a * TopicPartition, the committed offset (if applicable) or kafka param * auto.offset.reset will be used. */

@Experimental def Assign[K, V](

topicPartitions: ju.Collection[TopicPartition], kafkaParams: ju.Map[String, Object],

offsets: ju.Map[TopicPartition, jl.Long]): ConsumerStrategy[K, V] = { new Assign[K, V](topicPartitions, kafkaParams, offsets) } /**

* :: Experimental ::

* Assign a fixed collection of TopicPartitions

* @param topicPartitions collection of TopicPartitions to assign * @param kafkaParams Kanc630.comfka

* configuration parameters to be used on driver. The same params will be used on executors,

* with minor automatic modifications applied. * Requires \

* with Kafka broker(s) specified in host1:port1,host2:port2 form. */

@Experimental def Assign[K, V](

topicPartitions: ju.Collection[TopicPartition],

kafkaParams: ju.Map[String, Object]): ConsumerStrategy[K, V] = { new Assign[K, V]( topicPartitions, kafkaParams,

ju.Collections.emptyMap[TopicPartition, jl.Long]()) } }

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