scala - spark kafka producer serializable

Question

I come up with the exception:

ERROR yarn.ApplicationMaster: User class threw exception: org.apache.spark.SparkException: Task not serializable org.apache.spark.SparkException: Task not serializable at org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:304) at org.apache.spark.util.ClosureCleaner$.org$apache$spark$util$ClosureCleaner$$clean(ClosureCleaner.scala:294) at org.apache.spark.util.ClosureCleaner$.clean(ClosureCleaner.scala:122) at org.apache.spark.SparkContext.clean(SparkContext.scala:2032) at org.apache.spark.rdd.RDD$$anonfun$foreach$1.apply(RDD.scala:889) at org.apache.spark.rdd.RDD$$anonfun$foreach$1.apply(RDD.scala:888) at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:147) at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:108) at org.apache.spark.rdd.RDD.withScope(RDD.scala:306) at org.apache.spark.rdd.RDD.foreach(RDD.scala:888) at com.Boot$.test(Boot.scala:60) at com.Boot$.main(Boot.scala:36) at com.Boot.main(Boot.scala) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.apache.spark.deploy.yarn.ApplicationMaster$$anon$2.run(ApplicationMaster.scala:525) Caused by: java.io.NotSerializableException: org.apache.kafka.clients.producer.KafkaProducer Serialization stack: - object not serializable (class: org.apache.kafka.clients.producer.KafkaProducer, value: org.apache.kafka.clients.producer.KafkaProducer@77624599) - field (class: com.Boot$$anonfun$test$1, name: producer$1, type: class org.apache.kafka.clients.producer.KafkaProducer) - object (class com.Boot$$anonfun$test$1, ) at org.apache.spark.serializer.SerializationDebugger$.improveException(SerializationDebugger.scala:40) at org.apache.spark.serializer.JavaSerializationStream.writeObject(JavaSerializer.scala:47) at org.apache.spark.serializer.JavaSerializerInstance.serialize(JavaSerializer.scala:84) at org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:301)

//    @transient
val sparkConf = new SparkConf()

sparkConf.set("spark.serializer", "org.apache.spark.serializer.KryoSerializer")

//    @transient
val sc = new SparkContext(sparkConf)

val requestSet: RDD[String] = sc.textFile(s"hdfs:/user/bigdata/ADVERTISE-IMPRESSION-STAT*/*")

//    @transient
val props = new HashMap[String, Object]()
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, NearLineConfig.kafka_brokers)
//    props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.ByteArraySerializer");
//    props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.ByteArraySerializer");
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer")
props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer")
props.put("producer.type", "async")
props.put(ProducerConfig.BATCH_SIZE_CONFIG, "49152")

//    @transient
val producer: KafkaProducer[String, String] = new KafkaProducer[String, String](props)

requestSet.foreachPartition((partisions: Iterator[String]) => {
  partisions.foreach((line: String) => {
    try {
      producer.send(new ProducerRecord[String, String]("testtopic", line))
    } catch {
      case ex: Exception => {
        log.warn(ex.getMessage, ex)
      }
    }
  })
})

producer.close()

In this program i try to read the records from the hdfs path and save them into kafka. the problem is when I remove the codes about sending records to kafka , it runs well. What I missed ?

Answer 1

KafkaProducer isn't serializable. You'll need to move the creation of the instance to inside foreachPartition:

requestSet.foreachPartition((partitions: Iterator[String]) => {
  val producer: KafkaProducer[String, String] = new KafkaProducer[String, String](props)
  partitions.foreach((line: String) => {
    try {
      producer.send(new ProducerRecord[String, String]("testtopic", line))
    } catch {
      case ex: Exception => {
        log.warn(ex.getMessage, ex)
      }
    }
  })
})

Note that KafkaProducer.send returns a Future[RecordMetadata], and the only exception that can propagate from it is SerializationException if the key or value can't be serialized.