A NullPointerException in DictionaryValuesWriter when writing Parquet

A NullReference Exception happens when writing a large partitioned Spark dataframe to Parquet.

The job is running in AWS EMR 5.8.0 (Spark 2.1.1).

Exception:

```
17/09/05 16:40:33 ERROR Utils: Aborting task
java.lang.NullPointerException
at org.apache.parquet.it.unimi.dsi.fastutil.objects.Object2IntLinkedOpenHashMap.getInt(Object2IntLinkedOpenHashMap.java:590)
at org.apache.parquet.column.values.dictionary.DictionaryValuesWriter$PlainFixedLenArrayDictionaryValuesWriter.writeBytes(DictionaryValuesWriter.java:307)
at org.apache.parquet.column.values.fallback.FallbackValuesWriter.writeBytes(FallbackValuesWriter.java:162)
at org.apache.parquet.column.impl.ColumnWriterV1.write(ColumnWriterV1.java:201)
at org.apache.parquet.io.MessageColumnIO$MessageColumnIORecordConsumer.addBinary(MessageColumnIO.java:467)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport$$anonfun$org$apache$spark$sql$execution$datasources$parquet$ParquetWriteSupport$$makeWriter$10.apply(ParquetWriteSupport.scala:184)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport$$anonfun$org$apache$spark$sql$execution$datasources$parquet$ParquetWriteSupport$$makeWriter$10.apply(ParquetWriteSupport.scala:172)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport$$anonfun$org$apache$spark$sql$execution$datasources$parquet$ParquetWriteSupport$$writeFields$1.apply$mcV$sp(ParquetWriteSupport.scala:124)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport.org$apache$spark$sql$execution$datasources$parquet$ParquetWriteSupport$$consumeField(ParquetWriteSupport.scala:437)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport.org$apache$spark$sql$execution$datasources$parquet$ParquetWriteSupport$$writeFields(ParquetWriteSupport.scala:123)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport$$anonfun$write$1.apply$mcV$sp(ParquetWriteSupport.scala:114)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport.consumeMessage(ParquetWriteSupport.scala:425)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport.write(ParquetWriteSupport.scala:113)
at org.apache.spark.sql.execution.datasources.parquet.ParquetWriteSupport.write(ParquetWriteSupport.scala:51)
at org.apache.parquet.hadoop.InternalParquetRecordWriter.write(InternalParquetRecordWriter.java:123)
at org.apache.parquet.hadoop.ParquetRecordWriter.write(ParquetRecordWriter.java:180)
at org.apache.parquet.hadoop.ParquetRecordWriter.write(ParquetRecordWriter.java:46)
at org.apache.spark.sql.execution.datasources.parquet.ParquetOutputWriter.write(ParquetOutputWriter.scala:40)
at org.apache.spark.sql.execution.datasources.FileFormatWriter$DynamicPartitionWriteTask$$anonfun$execute$2.apply(FileFormatWriter.scala:465)
at org.apache.spark.sql.execution.datasources.FileFormatWriter$DynamicPartitionWriteTask$$anonfun$execute$2.apply(FileFormatWriter.scala:440)
at scala.collection.Iterator$class.foreach(Iterator.scala:893)
at org.apache.spark.sql.catalyst.util.AbstractScalaRowIterator.foreach(AbstractScalaRowIterator.scala:26)
at org.apache.spark.sql.execution.datasources.FileFormatWriter$DynamicPartitionWriteTask.execute(FileFormatWriter.scala:440)
at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask$3.apply(FileFormatWriter.scala:258)
at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask$3.apply(FileFormatWriter.scala:256)
at org.apache.spark.util.Utils$.tryWithSafeFinallyAndFailureCallbacks(Utils.scala:1375)
at org.apache.spark.sql.execution.datasources.FileFormatWriter$.org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask(FileFormatWriter.scala:261)
at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$write$1$$anonfun$apply$mcV$sp$1.apply(FileFormatWriter.scala:191)
at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$write$1$$anonfun$apply$mcV$sp$1.apply(FileFormatWriter.scala:190)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
at org.apache.spark.scheduler.Task.run(Task.scala:108)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:335)
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)}}
```

**Reporter**: [Irina Truong](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=irinatruong)

_{**Note**: *This issue was originally created as [PARQUET-1089](https://issues.apache.org/jira/browse/PARQUET-1089). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Beginne in parquet-column/src/main/java/org/apache/parquet/column/values/dictionary/DictionaryValuesWriter.java, insbesondere im writeBytes-Pfad an der Stelle des Stacktraces. Reproduziere den Fehler mit einem großen partitionierten Spark-Dataframe, das unter den gemeldeten Spark- und AWS-EMR-Versionen nach Parquet schreibt, und verfolge anschließend die Interaktion mit FallbackValuesWriter. Erledigt ist die Aufgabe, wenn die NullPointerException verstanden und verhindert ist und ein Regressionstest den gemeldeten Fall abdeckt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.