From 55942cb2dda4e10f518c32186aea54029b7eceda Mon Sep 17 00:00:00 2001
From: Forest Fang <forest.fang@outlook.com>
Date: Sun, 22 Nov 2015 17:51:43 -0500
Subject: [PATCH] started + completed should < total for progressbar

---
 core/src/main/scala/org/apache/spark/ui/UIUtils.scala  |  4 +++-
 .../test/scala/org/apache/spark/ui/UIUtilsSuite.scala  | 10 ++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

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 25dcb604d9e5f..84a1116a5c498 100644
--- a/core/src/main/scala/org/apache/spark/ui/UIUtils.scala
+++ b/core/src/main/scala/org/apache/spark/ui/UIUtils.scala
@@ -319,7 +319,9 @@ private[spark] object UIUtils extends Logging {
       skipped: Int,
       total: Int): Seq[Node] = {
     val completeWidth = "width: %s%%".format((completed.toDouble/total)*100)
-    val startWidth = "width: %s%%".format((started.toDouble/total)*100)
+    // started + completed can be > total when there are speculative tasks
+    val boundedStarted = math.min(started, total - completed)
+    val startWidth = "width: %s%%".format((boundedStarted.toDouble/total)*100)
 
     <div class="progress">
       <span style="text-align:center; position:absolute; width:100%; left:0;">
diff --git a/core/src/test/scala/org/apache/spark/ui/UIUtilsSuite.scala b/core/src/test/scala/org/apache/spark/ui/UIUtilsSuite.scala
index 2b693c165180f..dd8d5ec27f87e 100644
--- a/core/src/test/scala/org/apache/spark/ui/UIUtilsSuite.scala
+++ b/core/src/test/scala/org/apache/spark/ui/UIUtilsSuite.scala
@@ -57,6 +57,16 @@ class UIUtilsSuite extends SparkFunSuite {
     )
   }
 
+  test("SPARK-11906: Progress bar should not overflow because of speculative tasks") {
+    val generated = makeProgressBar(2, 3, 0, 0, 4).head.child.filter(_.label == "div")
+    val expected = Seq(
+      <div class="bar bar-completed" style="width: 75.0%"></div>,
+      <div class="bar bar-running" style="width: 25.0%"></div>
+    )
+    assert(generated.sameElements(expected),
+      s"\nRunning progress bar should round down\n\nExpected:\n$expected\nGenerated:\n$generated")
+  }
+
   private def verify(
       desc: String, expected: Elem, errorMsg: String = "", baseUrl: String = ""): Unit = {
     val generated = makeDescription(desc, baseUrl)