Fix the potential dead-lock in StreamingListenerSuite

Author: zsxwing

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

@@ -222,7 +222,11 @@ class StreamingListenerSuite extends TestSuiteBase with Matchers {
     val batchCounter = new BatchCounter(_ssc)
     _ssc.start()
     // Make sure running at least one batch
-    batchCounter.waitUntilBatchesCompleted(expectedNumCompletedBatches = 1, timeout = 10000)
+    if (!batchCounter.waitUntilBatchesCompleted(expectedNumCompletedBatches = 1, timeout = 10000)) {
+      fail("The first batch cannot complete in 10 seconds")
+    }
+    // When reaching here, we can make sure `StreamingContextStoppingCollector` won't call
+    // `ssc.stop()`, so it's safe to call `_ssc.stop()` now.
     _ssc.stop()
     assert(contextStoppingCollector.sparkExSeen)
   }
@@ -345,12 +349,21 @@ class FailureReasonsCollector extends StreamingListener {
  */
 class StreamingContextStoppingCollector(val ssc: StreamingContext) extends StreamingListener {
   @volatile var sparkExSeen = false
+
+  private var isFirstBatch = true
+
   override def onBatchCompleted(batchCompleted: StreamingListenerBatchCompleted) {
-    try {
-      ssc.stop()
-    } catch {
-      case se: SparkException =>
-        sparkExSeen = true
+    if (isFirstBatch) {
+      // We should only call `ssc.stop()` in the first batch. Otherwise, it's possible that the main
+      // thread is calling `ssc.stop()`, while StreamingContextStoppingCollector is also calling
+      // `ssc.stop()` in the listener thread, which becomes a dead-lock.
+      isFirstBatch = false
+      try {
+        ssc.stop()
+      } catch {
+        case se: SparkException =>
+          sparkExSeen = true
+      }
     }
   }
 }