Github user srowen commented on the pull request:
https://github.com/apache/spark/pull/4534#issuecomment-73955339
I think I have a solution. A `Seq[Nothing]` must be empty since there are
no instances of `Nothing`. So I think this can be fixed (and optimized) by
returning an `EmptyRDD` from `parallelize` when given an empty argument.
```
def parallelize[T: ClassTag](seq: Seq[T], numSlices: Int =
defaultParallelism): RDD[T] = {
assertNotStopped()
if (seq.isEmpty) {
new EmptyRDD[T](this)
} else {
new ParallelCollectionRDD[T](this, seq, numSlices, Map[Int,
Seq[String]]())
}
}
```
Witness:
```
scala> sc.parallelize(Seq(), 1).isEmpty
res0: Boolean = true
scala> sc.parallelize(Seq(), 1).take(1)
res1: Array[Nothing] = Array()
```
It deserves a unit test for both of these and a run through all the tests.
Want to try that?
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