尝试通过Java SDK将记录从Spark DataFrame写入Dynamodb时，任务无法序列化 [英] Task not serializable when trying to write record from Spark DataFrame to Dynamodb via Java SDK

问题描述

这是代码段:

val client = AmazonDynamoDBClientBuilder.standard.withRegion(Regions.the_region).withCredentials(new AWSStaticCredentialsProvider(new BasicAWSCredentials("access_key", "secret_key"))).build()
val dynamoDB = new DynamoDB(client)
val table = dynamoDB.getTable("tbl_name")

def putItem(email: String, name: String): Unit = {
    val item = new Item().withPrimaryKey("email", email).withNumber("ts", System.currentTimeMillis).withString("name", name)
    table.putItem(item)
}

spark.sql("""
select
    email,
    name
from db.hive_table_name
""").rdd.repartition(40).map(row => putItem(row.getString(0), row.getString(1))).collect()

我打算通过AWS提供的Java SDK将每条记录写入Dynamodb表，但是它抱怨如下错误:

I intend to write every record to Dynamodb table via Java SDK provided by AWS, but it complains error as below:

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$$clean(ClosureCleaner.scala:288)
at org.apache.spark.util.ClosureCleaner$.clean(ClosureCleaner.scala:108)
at org.apache.spark.SparkContext.clean(SparkContext.scala:2094)
at org.apache.spark.rdd.RDD$$anonfun$map$1.apply(RDD.scala:370)
at org.apache.spark.rdd.RDD$$anonfun$map$1.apply(RDD.scala:369)
at org.apache.spark.rdd.RDDOperationScope$.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.map(RDD.scala:369)

我如何调整代码以便在每个分区上创建 DynamoDB 和 Table 对象，以便利用Spark作业的并行性.谢谢！

How could I adjust the code in order to create the DynamoDB and Table object per partition in order to take the advantage of parallelism of Spark job. Thanks!

推荐答案

而不是 map 和 collect ，我会使用 foreachPartition :

spark.sql(query).rdd.repartition(40).foreachPartition(iter => {

  val client = AmazonDynamoDBClientBuilder.standard.withRegion(Regions.the_region)
    .withCredentials(new AWSStaticCredentialsProvider(new BasicAWSCredentials("access_key", "secret_key"))).build()
  val dynamoDB = new DynamoDB(client)
  val table = dynamoDB.getTable("tbl_name")


  iter.foreach(row => putItem(row.getString(0), row.getString(1)))
})

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