Github user vanzin commented on a diff in the pull request:
https://github.com/apache/spark/pull/1218#discussion_r15544774
--- Diff: core/src/main/scala/org/apache/spark/SparkContext.scala ---
@@ -1531,18 +1532,6 @@ object SparkContext extends Logging {
throw new SparkException("YARN mode not available ?", e)
}
}
- val backend = try {
- val clazz =
-
Class.forName("org.apache.spark.scheduler.cluster.YarnClusterSchedulerBackend")
- val cons = clazz.getConstructor(classOf[TaskSchedulerImpl],
classOf[SparkContext])
- cons.newInstance(scheduler,
sc).asInstanceOf[CoarseGrainedSchedulerBackend]
- } catch {
- case e: Exception => {
- throw new SparkException("YARN mode not available ?", e)
- }
- }
- scheduler.initialize(backend)
- scheduler
--- End diff --
So, what happened is that when I wrote this code there was no such thing as
YarnClusterScheduler. So I created it, and moved its initialization to the
backend class. Later someone else added the same class and I just merged my
code with theirs.
I think this is cleaner because it removes reflection code from
SparkContext. Unless you think that someone will ever try to match
YarnClusterSchedulerBackend with something other than YarnClusterScheduler.
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