Accumulator.scala (Since version 2.0.0) use AccumulatorV2
import org.apache.spark.util._
val accum=new DoubleAccumulator()
Array(1, 2, 3, 4).foreach(x => accum.add(x))
accum.value
res4: Double = 10.0
accum.avg
res5: Double = 2.5
accum.count
res6: Long = 4
accum.sum
res7: Double = 10.0