ParquetReader not using FileSystem cache effectively?

We've seen spark job stucked with following trace:

java.util.HashMap.put(HashMap.java:494)
org.apache.hadoop.conf.Configuration.set(Configuration.java:1065)
org.apache.hadoop.conf.Configuration.set(Configuration.java:1035)
org.apache.hadoop.fs.viewfs.HDFSCompatibleViewFileSystem.mergeViewFsHdfsMountPoints(HDFSCompatibleViewFileSystem.java:491)
org.apache.hadoop.fs.viewfs.HDFSCompatibleViewFileSystem.mergeConfFromDirectory(HDFSCompatibleViewFileSystem.java:413)
org.apache.hadoop.fs.viewfs.HDFSCompatibleViewFileSystem.mergeViewFsAndHdfs(HDFSCompatibleViewFileSystem.java:273)
org.apache.hadoop.fs.viewfs.HDFSCompatibleViewFileSystem.initialize(HDFSCompatibleViewFileSystem.java:190)
org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:2438)
org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:90)
org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:2472)
org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2454)
org.apache.hadoop.fs.FileSystem.get(FileSystem.java:384)
org.apache.hadoop.fs.Path.getFileSystem(Path.java:296)
parquet.hadoop.ParquetFileReader.readFooter(ParquetFileReader.java:384)
parquet.hadoop.ParquetRecordReader.initializeInternalReader(ParquetRecordReader.java:157)
parquet.hadoop.ParquetRecordReader.initialize(ParquetRecordReader.java:140)
org.apache.spark.rdd.NewHadoopRDD$$anon$1.(NewHadoopRDD.scala:133)
org.apache.spark.rdd.NewHadoopRDD.compute(NewHadoopRDD.scala:104)
org.apache.spark.rdd.NewHadoopRDD.compute(NewHadoopRDD.scala:66)
org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
org.apache.spark.rdd.NewHadoopRDD$NewHadoopMapPartitionsWithSplitRDD.compute(NewHadoopRDD.scala:244)
org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:35)
org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:35)
org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:35)
org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:35)
org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:68)
org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
org.apache.spark.scheduler.Task.run(Task.scala:64)
org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:203)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
java.lang.Thread.run(Thread.java:745)

**Reporter**: [Tim](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=tianshuo) / @tsdeng

_{**Note**: *This issue was originally created as [PARQUET-328](https://issues.apache.org/jira/browse/PARQUET-328). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

parquet.hadoop.ParquetFileReader.readFooter と ParquetRecordReader.initializeInternalReader から開始し、スタックトレースに示されている Hadoop FileSystem キャッシュの呼び出しを追跡します。Spark ジョブの動作を再現し、ファイルシステムの初期化が繰り返し発生しているかどうかを判断します。キャッシュの動作を理解し、報告された停止が解決されるか、回帰テストによって明確に問題ではないと判断できれば完了です。

索引モデルが issue の本文から書いたものです。