Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/9264#discussion_r44856611
--- Diff: core/src/main/scala/org/apache/spark/rdd/AsyncRDDActions.scala ---
@@ -66,14 +65,22 @@ class AsyncRDDActions[T: ClassTag](self: RDD[T])
extends Serializable with Loggi
*/
def takeAsync(num: Int): FutureAction[Seq[T]] = self.withScope {
val f = new ComplexFutureAction[Seq[T]]
-
- f.run {
- // This is a blocking action so we should use
"AsyncRDDActions.futureExecutionContext" which
- // is a cached thread pool.
- val results = new ArrayBuffer[T](num)
- val totalParts = self.partitions.length
- var partsScanned = 0
- while (results.size < num && partsScanned < totalParts) {
+ // Cached thread pool to handle aggregation of subtasks.
+ implicit val executionContext = AsyncRDDActions.futureExecutionContext
+ val results = new ArrayBuffer[T](num)
+ val totalParts = self.partitions.length
+
+ /*
+ Recursively triggers jobs to scan partitions until either the
requested
+ number of elements are retrieved, or the partitions to scan are
exhausted.
+ This implementation is non-blocking, asynchronously handling the
+ results of each job and triggering the next job using callbacks on
futures.
+ */
+ def continue(partsScanned : Int) : Future[Seq[T]] =
+ if (results.size >= num || partsScanned >= totalParts) {
+ Future.successful(results.toSeq)
+ }
--- End diff --
`else` on same line
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