No output operations registered, so nothing to execute

SparkStreaming和KafKa结合报错！报错之前代码如下:

 object KafkaWordCount{
    val updateFunc = (iter:Iterator[(String,Seq[Int],Option[Int])])=>{
       iter.flatMap{case(x,y,z) => Some(y.sum+z.getOrElse(0)).map(i => (x,i))}
    }
    def main(args: Array[String]): Unit = {
       val Array(zkQuorum, group, topics, numThreads) = args
       val sparkConf = new SparkConf().setAppName("KafkaWordCount").setMaster("local[2]")
       val ssc = new StreamingContext(sparkConf, Seconds(5))
       ssc.checkpoint("c://ck2")
       val topicMap = topics.split(",").map((_, numThreads.toInt)).toMap
       val data = KafkaUtils.createStream(ssc, zkQuorum, group, topicMap, StorageLevel.MEMORY_AND_DISK_SER)
       val words = data.map(_._2).flatMap(_.split(" "))
       val wordCounts = words.map((_, 1)).updateStateByKey(updateFunc, new HashPartitioner(ssc.sparkContext.defaultParallelism), true)
       println(wordCounts)
       ssc.start()
       ssc.awaitTermination()
    }
 }

注意:  在14行 应该是 wordCounts.print()  报错原因 :  在使用Streaming 的时候需要触发如下方法 print否则出现如下的错误

 17/07/28 17:11:59 ERROR StreamingContext: Error starting the context, marking it as stopped
 java.lang.IllegalArgumentException: requirement failed: No output operations registered, so nothing to execute
     at scala.Predef$.require(Predef.scala:233)
     at org.apache.spark.streaming.DStreamGraph.validate(DStreamGraph.scala:161)
     at org.apache.spark.streaming.StreamingContext.validate(StreamingContext.scala:542)
     at org.apache.spark.streaming.StreamingContext.liftedTree1$1(StreamingContext.scala:601)
     at org.apache.spark.streaming.StreamingContext.start(StreamingContext.scala:600)
     at org.bianqi.spark.day5.KafkaWordCount$.main(KafkaWordCount.scala:24)
     at org.bianqi.spark.day5.KafkaWordCount.main(KafkaWordCount.scala)
 Exception in thread "main" java.lang.IllegalArgumentException: requirement failed: No output operations registered, so nothing to execute
     at scala.Predef$.require(Predef.scala:233)

修改后的代码如下:

 object KafkaWordCount{
    val updateFunc = (iter:Iterator[(String,Seq[Int],Option[Int])])=>{
       iter.flatMap{case(x,y,z) => Some(y.sum+z.getOrElse(0)).map(i => (x,i))}
    }
    def main(args: Array[String]): Unit = {
       val Array(zkQuorum, group, topics, numThreads) = args
       val sparkConf = new SparkConf().setAppName("KafkaWordCount").setMaster("local[2]")
       val ssc = new StreamingContext(sparkConf, Seconds(5))
       ssc.checkpoint("c://ck2")
       val topicMap = topics.split(",").map((_, numThreads.toInt)).toMap
       val data = KafkaUtils.createStream(ssc, zkQuorum, group, topicMap, StorageLevel.MEMORY_AND_DISK_SER)
       val words = data.map(_._2).flatMap(_.split(" "))
       val wordCounts = words.map((_, 1)).updateStateByKey(updateFunc, new HashPartitioner(ssc.sparkContext.defaultParallelism), true)
       wordCounts.print()
       ssc.start()
       ssc.awaitTermination()
    }
 }

但是在stackoverflow上看到 报这样的错误 会是另外一在原因 具体地址如下:

https://stackoverflow.com/questions/34188274/spark-no-output-operations-registered-so-nothing-to-execute