scala - 将RDD保存到HDFS时出错

Question

我正在尝试使用Scala将RDD保存到HDFS中，但出现此错误:

WARN scheduler.TaskSetManager: Lost task 0.0 in stage 3.0 (TID 3, quickstart.cloudera, executor 3): java.lang.NumberFormatException: empty String
        at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1020)
        at java.lang.Float.parseFloat(Float.java:452)
        at scala.collection.immutable.StringLike$class.toFloat(StringLike.scala:231)
        at scala.collection.immutable.StringOps.toFloat(StringOps.scala:31)
        at $line24.$read$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$anonfun$1.apply(<console>:33)
        at $line24.$read$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$anonfun$1.apply(<console>:33)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
        at org.apache.spark.rdd.PairRDDFunctions$$anonfun$saveAsHadoopDataset$1$$anonfun$13$$anonfun$apply$7.apply$mcV$sp(PairRDDFunctions.scala:1196)
        at org.apache.spark.rdd.PairRDDFunctions$$anonfun$saveAsHadoopDataset$1$$anonfun$13$$anonfun$apply$7.apply(PairRDDFunctions.scala:1195)
        at org.apache.spark.rdd.PairRDDFunctions$$anonfun$saveAsHadoopDataset$1$$anonfun$13$$anonfun$apply$7.apply(PairRDDFunctions.scala:1195)
        at org.apache.spark.util.Utils$.tryWithSafeFinallyAndFailureCallbacks(Utils.scala:1279)
        at org.apache.spark.rdd.PairRDDFunctions$$anonfun$saveAsHadoopDataset$1$$anonfun$13.apply(PairRDDFunctions.scala:1203)
        at org.apache.spark.rdd.PairRDDFunctions$$anonfun$saveAsHadoopDataset$1$$anonfun$13.apply(PairRDDFunctions.scala:1183)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
        at org.apache.spark.scheduler.Task.run(Task.scala:89)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:242)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)

首先，我读取了位于HDFS中的文件，并且文件读取正确。之后，我尝试进行一些转换，例如更改字段定界符(管道)，然后将其写回到HDFS中。如果有人可以帮助我，这是我的代码。

val productsRDD= sc.textFile("/user/cloudera/products/products")
val products2RDD=productsRDD.map(a=>a.split(","))
case class clas1(product_id: Int,product_category_id: Int,product_name: String,product_description: String,product_price: Float,product_image: String)
val products = products2RDD.map(b => clas1(Integer.parseInt(0),Integer.parseInt(1),(2).toString,(3).toString,(4).toFloat,(5).toString))
val r = products.toDF()
r.registerTempTable("productsDF")
val prodDF = sqlContext.sql("select * from productsDF where product_price > 100")

/* everything goes fine until this line*/

prodDF.map(c => c(0)+"|"+c(1)+"|"+c(2)+"|"+c(3)+"|"+c(4)+"|"+c(5)).saveAsTextFile("/user/cloudera/problem1/pipes1")

数据框的字段:

| Field               | Type         | Null | Key | Default | Extra          |
+---------------------+--------------+------+-----+---------+----------------+
| product_id          | int(11)      | NO   | PRI | NULL    | auto_increment |
| product_category_id | int(11)      | NO   |     | NULL    |                |
| product_name        | varchar(45)  | NO   |     | NULL    |                |
| product_description | varchar(255) | NO   |     | NULL    |                |
| product_price       | float        | NO   |     | NULL    |                |
| product_image       | varchar(255) | NO   |     | NULL    |                |

我是Scala的新手，感谢您的帮助...
谢谢!

Answer 1

从错误中寻找-java.lang.NumberFormatException:空字符串

当您尝试从String中解析整数(字符串为空)时，似乎存在错误，因此您将遇到这种特殊问题。

您可以做的是在转换之前和拆分之后可以使用合并。创建一个数据框，spark-sql中有一个合并功能，它将用“NULL”替换您的空值