尝试使用 Spark 从 FTP 读取数据时出现以下错误。
WARN TaskSetManager: Lost task 0.0 in stage 0.0 (TID 0, localhost): java.io.IOException: Seek not supported
at org.apache.hadoop.fs.ftp.FTPInputStream.seek(FTPInputStream.java:62)
at org.apache.hadoop.fs.FSDataInputStream.seek(FSDataInputStream.java:62)
at org.apache.hadoop.mapred.LineRecordReader.<init>(LineRecordReader.java:127)
at org.apache.hadoop.mapred.TextInputFormat.getRecordReader(TextInputFormat.java:67)
at org.apache.spark.rdd.HadoopRDD$$anon$1.<init>(HadoopRDD.scala:245)
at org.apache.spark.rdd.HadoopRDD.compute(HadoopRDD.scala:208)
at org.apache.spark.rdd.HadoopRDD.compute(HadoopRDD.scala:101)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:319)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:283)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:319)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:283)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:319)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:283)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:70)
at org.apache.spark.scheduler.Task.run(Task.scala:86)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:274)
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)
看起来 FPT 服务器不支持搜索,而 Spark 默认尝试在内部使用搜索将文件拆分为更小的文件。
如何读取 FTP 文件没有任何问题?
最简单的方法是将文件作为一个整体读取,而不是使用查找。
下面的代码是 Java 中的答案:
String dataSource = "ftp://user:pwd/host/path/input.txt";
sparkContext.wholeTextFiles(dataSource).values().saveAsTextFile("/Users/parmarh/git/spark-rdd-dataframe-dataset/output/ftp/");
如果文件太大,缺点是非常慢......
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我来说两句