[SPARK-20242][Web UI] Add spark.ui.stopDelay

core/src/main/resources/org/apache/spark/ui/static/webui.css

@@ -250,4 +250,9 @@ a.expandbutton {
 
 .table-cell-width-limited td {
   max-width: 600px;
-}
+}
+
+.stop-delayed {
+  color: red;
+  margin-bottom: 1em;
+}

core/src/main/scala/org/apache/spark/ui/SparkUI.scala

@@ -18,22 +18,22 @@
 package org.apache.spark.ui
 
 import java.util.{Date, ServiceLoader}
+import java.util.concurrent.atomic.AtomicReference
 
 import scala.collection.JavaConverters._
 
 import org.apache.spark.{SecurityManager, SparkConf, SparkContext}
 import org.apache.spark.internal.Logging
 import org.apache.spark.scheduler._
-import org.apache.spark.status.api.v1.{ApiRootResource, ApplicationAttemptInfo, ApplicationInfo,
-  UIRoot}
+import org.apache.spark.status.api.v1.{ApiRootResource, ApplicationAttemptInfo, ApplicationInfo, UIRoot}
 import org.apache.spark.storage.StorageStatusListener
 import org.apache.spark.ui.JettyUtils._
 import org.apache.spark.ui.env.{EnvironmentListener, EnvironmentTab}
 import org.apache.spark.ui.exec.{ExecutorsListener, ExecutorsTab}
 import org.apache.spark.ui.jobs.{JobProgressListener, JobsTab, StagesTab}
 import org.apache.spark.ui.scope.RDDOperationGraphListener
 import org.apache.spark.ui.storage.{StorageListener, StorageTab}
-import org.apache.spark.util.Utils
+import org.apache.spark.util.{SignalUtils, Utils}
 
 /**
  * Top level user interface for a Spark application.
@@ -58,6 +58,9 @@ private[spark] class SparkUI private (
 
   val killEnabled = sc.map(_.conf.getBoolean("spark.ui.killEnabled", true)).getOrElse(false)
 
+  private val stopDelayThread = new AtomicReference[Thread]()
+  private val stopDelaySeconds = conf.getOption("spark.ui.stopDelay").map(Utils.timeStringAsSeconds)
+
   var appId: String = _
 
   private var streamingJobProgressListener: Option[SparkListener] = None
@@ -80,6 +83,9 @@ private[spark] class SparkUI private (
     attachHandler(createRedirectHandler(
       "/stages/stage/kill", "/stages/", stagesTab.handleKillRequest,
       httpMethods = Set("GET", "POST")))
+    attachHandler(createRedirectHandler(
+      "/proceed-with-ui-stop", "/jobs/", _ => proceedWithStop("web UI action"),
+      httpMethods = Set("GET", "POST")))
   }
   initialize()
 
@@ -93,10 +99,51 @@ private[spark] class SparkUI private (
     appId = id
   }
 
+  def activeStopDelay: Option[Long] =
+    stopDelaySeconds.filter(_ => stopDelayThread.get() != null)
+
   /** Stop the server behind this web interface. Only valid after bind(). */
   override def stop() {
-    super.stop()
-    logInfo(s"Stopped Spark web UI at $webUrl")
+
+    def reallyStop(): Unit = {
+      super.stop()
+      logInfo(s"Stopped Spark web UI at $webUrl")
+    }
+
+    stopDelaySeconds match {
+      case Some(stopDelaySeconds) =>
+        if (stopDelayThread.compareAndSet(null, Thread.currentThread())) {
+          delayStop(stopDelaySeconds)
+          reallyStop()
+        }
+      case None =>
+        reallyStop()
+    }
+  }
+
+  private def delayStop(stopDelaySeconds: Long): Unit = {
+
+    SignalUtils.register("INT") {
+      proceedWithStop(s"received SIGINT")
+      true
+    }
+
+    logInfo(s"Delaying stop of Spark web UI at $webUrl " +
+      s"for $stopDelaySeconds seconds as set in spark.ui.stopDelay. " +
+      s"Stopping can be resumed immediately in the Spark UI, or by sending SIGINT.")
+
+    try Thread.sleep(1000 * stopDelaySeconds)
+    catch { case _: InterruptedException => }
+
+    stopDelayThread.set(null)
+    Thread.interrupted()
+  }
+
+  def proceedWithStop(reason: String): Unit = {
+    Option(stopDelayThread.get).foreach { stopThread =>
+      logInfo(s"Proceeding to stop Spark web UI ($reason)")
+      stopThread.interrupt()
+    }
   }
 
   def getSparkUI(appId: String): Option[SparkUI] = {

core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala

@@ -311,6 +311,24 @@ private[ui] class AllJobsPage(parent: JobsTab) extends WebUIPage("") {
 
       val summary: NodeSeq =
         <div>
+          {
+            parent.activeStopDelay match {
+              case None =>
+              case Some(delay) =>
+                val confirm =
+                  s"if (window.confirm('Are you sure you allow the Spark UI to stop?')) " +
+                    "{ this.parentNode.submit(); return true; } else { return false; }"
+                val action = s"${parent.basePath}/proceed-with-ui-stop"
+                <div class="stop-delayed">
+                  <strong>The Spark UI has been asked to stop, but that is being delayed for
+                    {delay}s.
+                    <form action={action} method="POST" style="display:inline">
+                      <a href="#" onclick={confirm}>(stop now)</a>
+                    </form>
+                  </strong>
+                </div>
+            }
+          }
           <ul class="unstyled">
             <li>
               <strong>User:</strong>

core/src/main/scala/org/apache/spark/ui/jobs/JobsTab.scala

@@ -30,6 +30,9 @@ private[ui] class JobsTab(parent: SparkUI) extends SparkUITab(parent, "jobs") {
   val executorListener = parent.executorsListener
   val operationGraphListener = parent.operationGraphListener
 
+  def activeStopDelay: Option[Long] =
+    parent.activeStopDelay
+
   def isFairScheduler: Boolean =
     jobProgresslistener.schedulingMode == Some(SchedulingMode.FAIR)
 

docs/configuration.md

@@ -660,6 +660,13 @@ Apart from these, the following properties are also available, and may be useful
     finished.
   </td>
 </tr>
+<tr>
+  <td><code>spark.ui.stopDelay</code></td>
+  <td>(none)</td>
+  <td>
+    A period of time to delay the stopping of the Web UI, so that it can be inspected after the application finishes.
+  </td>
+</tr>
 <tr>
   <td><code>spark.ui.enabled</code></td>
   <td>true</td>