[SPARK-11761] Prevent the call to StreamingContext#stop() in the list…

…ener bus's thread

See discussion toward the tail of apache#9723
From zsxwing :
```
The user should not call stop or other long-time work in a listener since it will block the listener thread, and prevent from stopping SparkContext/StreamingContext.

I cannot see an approach since we need to stop the listener bus's thread before stopping SparkContext/StreamingContext totally.
```
Proposed solution is to prevent the call to StreamingContext#stop() in the listener bus's thread.

Author: tedyu <[email protected]>

Closes apache#9741 from tedyu/master.

core/src/main/scala/org/apache/spark/util/AsynchronousListenerBus.scala

@@ -19,6 +19,7 @@ package org.apache.spark.util
 
 import java.util.concurrent._
 import java.util.concurrent.atomic.AtomicBoolean
+import scala.util.DynamicVariable
 
 import org.apache.spark.SparkContext
 
@@ -60,25 +61,27 @@ private[spark] abstract class AsynchronousListenerBus[L <: AnyRef, E](name: Stri
   private val listenerThread = new Thread(name) {
     setDaemon(true)
     override def run(): Unit = Utils.tryOrStopSparkContext(sparkContext) {
-      while (true) {
-        eventLock.acquire()
-        self.synchronized {
-          processingEvent = true
-        }
-        try {
-          val event = eventQueue.poll
-          if (event == null) {
-            // Get out of the while loop and shutdown the daemon thread
-            if (!stopped.get) {
-              throw new IllegalStateException("Polling `null` from eventQueue means" +
-                " the listener bus has been stopped. So `stopped` must be true")
-            }
-            return
-          }
-          postToAll(event)
-        } finally {
+      AsynchronousListenerBus.withinListenerThread.withValue(true) {
+        while (true) {
+          eventLock.acquire()
           self.synchronized {
-            processingEvent = false
+            processingEvent = true
+          }
+          try {
+            val event = eventQueue.poll
+            if (event == null) {
+              // Get out of the while loop and shutdown the daemon thread
+              if (!stopped.get) {
+                throw new IllegalStateException("Polling `null` from eventQueue means" +
+                  " the listener bus has been stopped. So `stopped` must be true")
+              }
+              return
+            }
+            postToAll(event)
+          } finally {
+            self.synchronized {
+              processingEvent = false
+            }
           }
         }
       }
@@ -177,3 +180,10 @@ private[spark] abstract class AsynchronousListenerBus[L <: AnyRef, E](name: Stri
    */
   def onDropEvent(event: E): Unit
 }
+
+private[spark] object AsynchronousListenerBus {
+  /* Allows for Context to check whether stop() call is made within listener thread
+  */
+  val withinListenerThread: DynamicVariable[Boolean] = new DynamicVariable[Boolean](false)
+}
+

streaming/src/main/scala/org/apache/spark/streaming/StreamingContext.scala

@@ -44,7 +44,7 @@ import org.apache.spark.streaming.dstream._
 import org.apache.spark.streaming.receiver.{ActorReceiver, ActorSupervisorStrategy, Receiver}
 import org.apache.spark.streaming.scheduler.{JobScheduler, StreamingListener}
 import org.apache.spark.streaming.ui.{StreamingJobProgressListener, StreamingTab}
-import org.apache.spark.util.{CallSite, ShutdownHookManager, ThreadUtils, Utils}
+import org.apache.spark.util.{AsynchronousListenerBus, CallSite, ShutdownHookManager, ThreadUtils, Utils}
 
 /**
  * Main entry point for Spark Streaming functionality. It provides methods used to create
@@ -693,6 +693,10 @@ class StreamingContext private[streaming] (
    */
   def stop(stopSparkContext: Boolean, stopGracefully: Boolean): Unit = {
     var shutdownHookRefToRemove: AnyRef = null
+    if (AsynchronousListenerBus.withinListenerThread.value) {
+      throw new SparkException("Cannot stop StreamingContext within listener thread of" +
+        " AsynchronousListenerBus")
+    }
     synchronized {
       try {
         state match {

streaming/src/test/scala/org/apache/spark/streaming/StreamingListenerSuite.scala

@@ -21,6 +21,7 @@ import scala.collection.mutable.{ArrayBuffer, HashMap, SynchronizedBuffer, Synch
 import scala.concurrent.Future
 import scala.concurrent.ExecutionContext.Implicits.global
 
+import org.apache.spark.SparkException
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.streaming.dstream.DStream
 import org.apache.spark.streaming.receiver.Receiver
@@ -161,6 +162,14 @@ class StreamingListenerSuite extends TestSuiteBase with Matchers {
     }
   }
 
+  test("don't call ssc.stop in listener") {
+    ssc = new StreamingContext("local[2]", "ssc", Milliseconds(1000))
+    val inputStream = ssc.receiverStream(new StreamingListenerSuiteReceiver)
+    inputStream.foreachRDD(_.count)
+
+    startStreamingContextAndCallStop(ssc)
+  }
+
   test("onBatchCompleted with successful batch") {
     ssc = new StreamingContext("local[2]", "test", Milliseconds(1000))
     val inputStream = ssc.receiverStream(new StreamingListenerSuiteReceiver)
@@ -207,6 +216,17 @@ class StreamingListenerSuite extends TestSuiteBase with Matchers {
     assert(failureReasons(1).contains("This is another failed job"))
   }
 
+  private def startStreamingContextAndCallStop(_ssc: StreamingContext): Unit = {
+    val contextStoppingCollector = new StreamingContextStoppingCollector(_ssc)
+    _ssc.addStreamingListener(contextStoppingCollector)
+    val batchCounter = new BatchCounter(_ssc)
+    _ssc.start()
+    // Make sure running at least one batch
+    batchCounter.waitUntilBatchesCompleted(expectedNumCompletedBatches = 1, timeout = 10000)
+    _ssc.stop()
+    assert(contextStoppingCollector.sparkExSeen)
+  }
+
   private def startStreamingContextAndCollectFailureReasons(
       _ssc: StreamingContext, isFailed: Boolean = false): Map[Int, String] = {
     val failureReasonsCollector = new FailureReasonsCollector()
@@ -320,3 +340,17 @@ class FailureReasonsCollector extends StreamingListener {
     }
   }
 }
+/**
+ * A StreamingListener that calls StreamingContext.stop().
+ */
+class StreamingContextStoppingCollector(val ssc: StreamingContext) extends StreamingListener {
+  @volatile var sparkExSeen = false
+  override def onBatchCompleted(batchCompleted: StreamingListenerBatchCompleted) {
+    try {
+      ssc.stop()
+    } catch {
+      case se: SparkException =>
+        sparkExSeen = true
+    }
+  }
+}