Occasional corruption of parquet files , parquet writer might not be calling ParquetFileWriter->end()
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- Java
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説明
We have a high volume streaming service which works most of the time . But off late we have been observing that some of the parquet files written out by write flow are getting corrupted. This is manifested in our reading flow with the following exception
Writer version - 1.6.0 , Reader version - 1.7.0
Caused by: java.lang.RuntimeException: hdfs://Ingest/ingest/jobs/2017-11-30/00-05/part4139 is not a Parquet file. expected magic number at tail [80, 65, 82, 49] but found [-28, -126, 1, 1]
at org.apache.parquet.hadoop.ParquetFileReader.readFooter(ParquetFileReader.java:422)
at org.apache.parquet.hadoop.ParquetFileReader.readFooter(ParquetFileReader.java:385)
at org.apache.parquet.hadoop.ParquetRecordReader.initializeInternalReader(ParquetRecordReader.java:157)
at org.apache.parquet.hadoop.ParquetRecordReader.initialize(ParquetRecordReader.java:140)
at org.apache.spark.rdd.SqlNewHadoopRDD$$anon$1.(SqlNewHadoopRDD.scala:180)
at org.apache.spark.rdd.SqlNewHadoopRDD.compute(SqlNewHadoopRDD.scala:126)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:73)
at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
at org.apache.spark.scheduler.Task.run(Task.scala:89)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:227)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)```
After looking at the code , i can see that one of the possible causes is/are
1] footer not being serialized in the writer due to end not being called
but we are not seeing any exceptions on the writer.
2] data size - does data size has impact ? There will be cases when row group sizes will be huge as it is activity data of a user
We are using default parquet block size and hdfs block size . Other than upgrading to the latest version and re-test , what are the options we have to debug a issue like this
**Reporter**: [venkata yerubandi](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=raoyvn)
**Note**: *This issue was originally created as [PARQUET-1176](https://issues.apache.org/jira/browse/PARQUET-1176). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*
コントリビューションガイド
このリポジトリのコントリビューションガイドは索引されていません
調査の方向性
まず、ParquetFileReader.readFooter のスタックトレースの位置、特に ParquetFileReader.java:422 を確認し、writer パスで ParquetFileWriter->end() が呼び出されているかを調査します。row-group のサイズと HDFS ブロックサイズを変えながら、高ボリュームのストリーミングサービスで破損を再現します。末尾の magic number が欠落する原因を特定し、検証済みのデバッグまたは修正の手順を文書化できれば完了です。
索引モデルが issue の本文から書いたものです。
評価
- 技術スタック
- java, spark
- 領域
- data-engineering
- issue の種類
- バグ
- 難易度
- 4/5
- 見積もり時間
- 3〜5日
- 活発さ
- 停滞
- 明瞭さ
- 説明が足りない
- 初心者へのやさしさ
- 25/100