在实际开发中我们往往需要自己定义一些对于RDD的操作，那么此时需要主要的是，初始化工作是在Driver端进行的，而实际运行程序是在Executor端进行的，这就涉及到了跨进程通信，是需要序列化的。
传递一个方法
1．创建一个类
class Search(s:String){
//过滤出包含字符串的数据
def isMatch(s: String): Boolean = {
s.contains(query)
}
//过滤出包含字符串的RDD
def getMatch1 (rdd: RDD[String]): RDD[String] = {
rdd.filter(isMatch)
}
//过滤出包含字符串的RDD
def getMatche2(rdd: RDD[String]): RDD[String] = {
rdd.filter(x => x.contains(query))
}
}
2．创建Spark主程序
object SeriTest {
def main(args: Array[String]): Unit = {
//1.初始化配置信息及SparkContext
val sparkConf: SparkConf = new SparkConf().setAppName("WordCount").setMaster("local[*]")
val sc = new SparkContext(sparkConf)
//2.创建一个RDD
val rdd: RDD[String] = sc.parallelize(Array("hadoop", "spark", "hive", "atguigu"))
//3.创建一个Search对象
val search = new Search()
//4.运用第一个过滤函数并打印结果
val match1: RDD[String] = search.getMatche1(rdd)
match1.collect().foreach(println)
}
}
3．运行程序
Exception in thread "main" org.apache.spark.SparkException: Task not serializable
at org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:298)
at org.apache.spark.util.ClosureCleaner$.org$apache$spark$util$ClosureCleaner$$clean(ClosureCleaner.scala:288)
at org.apache.spark.util.ClosureCleaner$.clean(ClosureCleaner.scala:108)
at org.apache.spark.SparkContext.clean(SparkContext.scala:2101)
at org.apache.spark.rdd.RDD$$anonfun$filter$1.apply(RDD.scala:387)
at org.apache.spark.rdd.RDD$$anonfun$filter$1.apply(RDD.scala:386)
at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:151)
at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:112)
at org.apache.spark.rdd.RDD.withScope(RDD.scala:362)
at org.apache.spark.rdd.RDD.filter(RDD.scala:386)
at com.atguigu.Search.getMatche1(SeriTest.scala:39)
at com.atguigu.SeriTest$.main(SeriTest.scala:18)
at com.atguigu.SeriTest.main(SeriTest.scala)
Caused by: java.io.NotSerializableException: com.atguigu.Search
4．问题说明
//过滤出包含字符串的RDD
def getMatch1 (rdd: RDD[String]): RDD[String] = {
rdd.filter(isMatch)
}
在这个方法中所调用的方法isMatch()是定义在Search这个类中的，实际上调用的是this. isMatch()，this表示Search这个类的对象，程序在运行过程中需要将Search对象序列化以后传递到Executor端。
5．解决方案
使类继承scala.Serializable即可。
class Search() extends Serializable{
...}
传递一个属性
1．创建Spark主程序
object TransmitTest {
def main(args: Array[String]): Unit = {
//1.初始化配置信息及SparkContext
val sparkConf: SparkConf = new SparkConf().setAppName("WordCount").setMaster("local[*]")
val sc = new SparkContext(sparkConf)
//2.创建一个RDD
val rdd: RDD[String] = sc.parallelize(Array("hadoop", "spark", "hive", "atguigu"))
//3.创建一个Search对象
val search = new Search()
//4.运用第一个过滤函数并打印结果
val match1: RDD[String] = search.getMatche2(rdd)
match1.collect().foreach(println)
}
}
2．运行程序
Exception in thread "main" org.apache.spark.SparkException: Task not serializable
at org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:298)
at org.apache.spark.util.ClosureCleaner$.org$apache$spark$util$ClosureCleaner$$clean(ClosureCleaner.scala:288)
at org.apache.spark.util.ClosureCleaner$.clean(ClosureCleaner.scala:108)
at org.apache.spark.SparkContext.clean(SparkContext.scala:2101)
at org.apache.spark.rdd.RDD$$anonfun$filter$1.apply(RDD.scala:387)
at org.apache.spark.rdd.RDD$$anonfun$filter$1.apply(RDD.scala:386)
at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:151)
at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:112)
at org.apache.spark.rdd.RDD.withScope(RDD.scala:362)
at org.apache.spark.rdd.RDD.filter(RDD.scala:386)
at com.atguigu.Search.getMatche1(SeriTest.scala:39)
at com.atguigu.SeriTest$.main(SeriTest.scala:18)
at com.atguigu.SeriTest.main(SeriTest.scala)
Caused by: java.io.NotSerializableException: com.atguigu.Search
3．问题说明
//过滤出包含字符串的RDD
def getMatche2(rdd: RDD[String]): RDD[String] = {
rdd.filter(x => x.contains(query))
}
在这个方法中所调用的方法query是定义在Search这个类中的字段，实际上调用的是this. query，this表示Search这个类的对象，程序在运行过程中需要将Search对象序列化以后传递到Executor端。
4．解决方案
1）使类继承scala.Serializable即可。
class Search() extends Serializable{
...}
2）将类变量query赋值给局部变量
修改getMatche2为
//过滤出包含字符串的RDD
def getMatche2(rdd: RDD[String]): RDD[String] = {
val query_ : String = this.query//将类变量赋值给局部变量
rdd.filter(x => x.contains(query_))
}