3 files changed, 23 insertions, 3 deletions
diff --git a/core/src/main/resources/org/apache/spark/ui/static/spark-dag-viz.js b/core/src/main/resources/org/apache/spark/ui/static/spark-dag-viz.js
index 76eb2c4641..cda27cad7e 100644
--- a/core/src/main/resources/org/apache/spark/ui/static/spark-dag-viz.js
+++ b/core/src/main/resources/org/apache/spark/ui/static/spark-dag-viz.js
@@ -178,8 +178,8 @@ function renderDagVizForJob(svgContainer) {
     var stageId = metadata.attr("stage-id");
     var containerId = VizConstants.graphPrefix + stageId;
     // Link each graph to the corresponding stage page (TODO: handle stage attempts)
-    var stageLink =
-      "/stages/stage/?id=" + stageId.replace(VizConstants.stagePrefix, "") + "&attempt=0";
+    var stageLink = "/stages/stage/?id=" +
+      stageId.replace(VizConstants.stagePrefix, "") + "&attempt=0&expandDagViz=true";
     var container = svgContainer
       .append("a")
       .attr("xlink:href", stageLink)
diff --git a/core/src/main/scala/org/apache/spark/ui/UIUtils.scala b/core/src/main/scala/org/apache/spark/ui/UIUtils.scala
index e2d03f8342..97eed13c2d 100644
--- a/core/src/main/scala/org/apache/spark/ui/UIUtils.scala
+++ b/core/src/main/scala/org/apache/spark/ui/UIUtils.scala
@@ -20,7 +20,7 @@ package org.apache.spark.ui
 import java.text.SimpleDateFormat
 import java.util.{Locale, Date}
 
-import scala.xml.{Node, Text}
+import scala.xml.{Node, Text, Unparsed}
 
 import org.apache.spark.Logging
 import org.apache.spark.ui.scope.RDDOperationGraph
@@ -371,4 +371,12 @@ private[spark] object UIUtils extends Logging {
       </div>
     </div>
   }
+
+  /** Return a script element that automatically expands the DAG visualization on page load. */
+  def expandDagVizOnLoad(forJob: Boolean): Seq[Node] = {
+    <script type="text/javascript">
+      {Unparsed("$(document).ready(function() { toggleDagViz(" + forJob + ") });")}
+    </script>
+  }
+
 }
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala b/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala
index 579310070c..6c4305873c 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala
@@ -44,6 +44,10 @@ private[ui] class StagePage(parent: StagesTab) extends WebUIPage("stage") {
       val parameterAttempt = request.getParameter("attempt")
       require(parameterAttempt != null && parameterAttempt.nonEmpty, "Missing attempt parameter")
 
+      // If this is set, expand the dag visualization by default
+      val expandDagVizParam = request.getParameter("expandDagViz")
+      val expandDagViz = expandDagVizParam != null && expandDagVizParam.toBoolean
+
       val stageId = parameterId.toInt
       val stageAttemptId = parameterAttempt.toInt
       val stageDataOption = progressListener.stageIdToData.get((stageId, stageAttemptId))
@@ -174,6 +178,13 @@ private[ui] class StagePage(parent: StagesTab) extends WebUIPage("stage") {
       val dagViz = UIUtils.showDagVizForStage(
         stageId, operationGraphListener.getOperationGraphForStage(stageId))
 
+      val maybeExpandDagViz: Seq[Node] =
+        if (expandDagViz) {
+          UIUtils.expandDagVizOnLoad(forJob = false)
+        } else {
+          Seq.empty
+        }
+
       val accumulableHeaders: Seq[String] = Seq("Accumulable", "Value")
       def accumulableRow(acc: AccumulableInfo): Elem =
         <tr><td>{acc.name}</td><td>{acc.value}</td></tr>
@@ -440,6 +451,7 @@ private[ui] class StagePage(parent: StagesTab) extends WebUIPage("stage") {
         summary ++
         showAdditionalMetrics ++
         dagViz ++
+        maybeExpandDagViz ++
         <h4>Summary Metrics for {numCompleted} Completed Tasks</h4> ++
         <div>{summaryTable.getOrElse("No tasks have reported metrics yet.")}</div> ++
         <h4>Aggregated Metrics by Executor</h4> ++ executorTable.toNodeSeq ++