Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/3740#discussion_r22127764
--- Diff: core/src/main/scala/org/apache/spark/rdd/RDD.scala ---
@@ -1174,7 +1174,19 @@ abstract class RDD[T: ClassTag](
* Save this RDD as a text file, using string representations of
elements.
*/
def saveAsTextFile(path: String) {
- this.map(x => (NullWritable.get(), new Text(x.toString)))
+ // https://issues.apache.org/jira/browse/SPARK-2075
+ // NullWritable is a Comparable rather than Comparable[NullWritable]
in Hadoop 1.+,
+ // so the compiler cannot find an implicit Ordering for it and will
use the default `null`.
+ // It will generate different anonymous classes for `saveAsTextFile`
in Hadoop 1.+ and
+ // Hadoop 2.+. Therefore, here we provide an Ordering for NullWritable
so that the compiler
+ // will generate same bytecode.
+ val nullWritableOrdering = new Ordering[NullWritable] {
+ override def compare(x: NullWritable, y: NullWritable): Int = 0
+ }
+ val nullWritableClassTag = implicitly[ClassTag[NullWritable]]
+ val textClassTag = implicitly[ClassTag[Text]]
+ val r = this.map(x => (NullWritable.get(), new Text(x.toString)))
--- End diff --
here can be reused too
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