java.lang.String cannot be cast to org.apache.spark.unsafe.types.UTF8String

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问题

最近遇到一个问题，在用spark读取tensorflow的文件并写入时

//读数据
val df = spark.read.format("tfrecords").load(readPath).toDF()

//写数据
df.write.mode(SaveMode.Overwrite).format("tfrecords").option("recordType","Example").save(writePath)

出现如下报错：

org.apache.spark.SparkException: Task failed while writing rows
        at org.apache.spark.internal.io.SparkHadoopWriter$.org$apache$spark$internal$io$SparkHadoopWriter$$executeTask(SparkHadoopWriter.scala:155)
        at org.apache.spark.internal.io.SparkHadoopWriter$$anonfun$3.apply(SparkHadoopWriter.scala:83)
        at org.apache.spark.internal.io.SparkHadoopWriter$$anonfun$3.apply(SparkHadoopWriter.scala:78)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:90)
        at org.apache.spark.scheduler.Task.run(Task.scala:121)
        at org.apache.spark.executor.Executor$TaskRunner$$anonfun$11.apply(Executor.scala:407)
        at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:413)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to org.apache.spark.unsafe.types.UTF8String
        at org.apache.spark.sql.catalyst.util.GenericArrayData.getUTF8String(GenericArrayData.scala:75)
        at org.apache.spark.sql.catalyst.InternalRow$$anonfun$getAccessor$8.apply(InternalRow.scala:136)
        at org.apache.spark.sql.catalyst.InternalRow$$anonfun$getAccessor$8.apply(InternalRow.scala:136)
        at org.apache.spark.sql.catalyst.util.ArrayData.toArray(ArrayData.scala:178)
        at org.tensorflow.spark.datasources.tfrecords.serde.DefaultTfRecordRowEncoder$.org$tensorflow$spark$datasources$tfrecords$serde$DefaultTfRecordRowEncoder$$encodeFeature(DefaultTfRecordRowEncoder.scala:132)
        at org.tensorflow.spark.datasources.tfrecords.serde.DefaultTfRecordRowEncoder$$anonfun$encodeExample$1.apply(DefaultTfRecordRowEncoder.scala:64)
        at org.tensorflow.spark.datasources.tfrecords.serde.DefaultTfRecordRowEncoder$$anonfun$encodeExample$1.apply(DefaultTfRecordRowEncoder.scala:61)
        at scala.collection.immutable.List.foreach(List.scala:392)
        at org.tensorflow.spark.datasources.tfrecords.serde.DefaultTfRecordRowEncoder$.encodeExample(DefaultTfRecordRowEncoder.scala:61)
        at org.tensorflow.spark.datasources.tfrecords.DefaultSource$$anonfun$2.apply(DefaultSource.scala:59)
        at org.tensorflow.spark.datasources.tfrecords.DefaultSource$$anonfun$2.apply(DefaultSource.scala:56)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:410)
        at org.apache.spark.internal.io.SparkHadoopWriter$$anonfun$4.apply(SparkHadoopWriter.scala:129)
        at org.apache.spark.internal.io.SparkHadoopWriter$$anonfun$4.apply(SparkHadoopWriter.scala:127)
        at org.apache.spark.util.Utils$.tryWithSafeFinallyAndFailureCallbacks(Utils.scala:1394)
        at org.apache.spark.internal.io.SparkHadoopWriter$.org$apache$spark$internal$io$SparkHadoopWriter$$executeTask(SparkHadoopWriter.scala:139)
        ... 10 more

我用的是jar包是：spark-tensorflow-connector_2.11-1.6.0.jar

解决方案：

主要是版本的问题，更换spark connector的jar包

spark-tensorflow-connector_2.11-1.14.0.jar

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