Add log message on rate update

Author: huitseeker

streaming/src/main/scala/org/apache/spark/streaming/receiver/ReceiverSupervisorImpl.scala

@@ -77,8 +77,10 @@ private[streaming] class ReceiverSupervisorImpl(
         case CleanupOldBlocks(threshTime) =>
           logDebug("Received delete old batch signal")
           cleanupOldBlocks(threshTime)
-        case RateLimitUpdate(eps) =>
+        case RateLimitUpdate(eps) => {
           blockGenerator.updateRate(eps.toInt)
+          logDebug(s"Received update for $streamId : $eps")
+        }
       }
     })