context.hadoopConfiguration.set(XmlInputFormat.START_TAG_KEY, s"<$rowTag>")
 context.hadoopConfiguration.set(XmlInputFormat.END_TAG_KEY, s"</$rowTag>")
 context.hadoopConfiguration.set(XmlInputFormat.ENCODING_KEY, charset)

val failedAgesSet = mutable.Set[Long]()
    val threads_ages = (1 to 10).map { i =>
      new Thread {
        override def run() {
          val df = spark.read.option("rowTag", "person").format("xml")
            .load(resDir + "ages.xml")
          if (df.schema.fields.isEmpty) {
            failedAgesSet.add(i)
          }
        }
      }
    }

    val failedBooksSet = mutable.Set[Long]()
    val threads_books = (11 to 20).map { i =>
      new Thread {
        override def run() {
          val df = spark.read.option("rowTag", "book").format("xml")
            .load(resDir + "books.xml")
          if (df.schema.fields.isEmpty) {
            failedBooksSet.add(i)
          }
        }
      }
    }

    threads_ages.foreach(_.start())
    threads_books.foreach(_.start())
    threads_ages.foreach(_.join())
    threads_books.foreach(_.join())
    assert(failedBooksSet.isEmpty)
    assert(failedAgesSet.isEmpty)