diff --git a/core/src/main/scala/org/apache/spark/deploy/master/MasterSource.scala b/core/src/main/scala/org/apache/spark/deploy/master/MasterSource.scala
index 9c3f79f124..66a9ff3867 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/MasterSource.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/MasterSource.scala
@@ -30,6 +30,11 @@ private[spark] class MasterSource(val master: Master) extends Source {
     override def getValue: Int = master.workers.size
   })
 
+  // Gauge for alive worker numbers in cluster
+  metricRegistry.register(MetricRegistry.name("aliveWorkers"), new Gauge[Int]{
+    override def getValue: Int = master.workers.filter(_.state == WorkerState.ALIVE).size
+  })
+
   // Gauge for application numbers in cluster
   metricRegistry.register(MetricRegistry.name("apps"), new Gauge[Int] {
     override def getValue: Int = master.apps.size