Input of the SparkPi is too big

if the Input of the SparkPi is too big, it will  throw new UnsupportedOperationException("empty collection"), because the n may be a negative int number.

Author: SaintBacchus

examples/src/main/scala/org/apache/spark/examples/SparkPi.scala

@@ -27,7 +27,7 @@ object SparkPi {
     val conf = new SparkConf().setAppName("Spark Pi")
     val spark = new SparkContext(conf)
     val slices = if (args.length > 0) args(0).toInt else 2
-    val n = 100000 * slices
+    val n = if (100000.toLong * slices > Int.MaxValue) Int.MaxValue - 1 else 100000 * slices
     val count = spark.parallelize(1 to n, slices).map { i =>
       val x = random * 2 - 1
       val y = random * 2 - 1