[SPARK-13164][CORE] Replace deprecated synchronized buffer in core

Building with scala 2.11 results in the warning trait SynchronizedBuffer in package mutable is deprecated: Synchronization via traits is deprecated as it is inherently unreliable. Consider java.util.concurrent.ConcurrentLinkedQueue as an alternative. Investigation shows we are already using ConcurrentLinkedQueue in other locations so switch our uses of SynchronizedBuffer to ConcurrentLinkedQueue.

Author: Holden Karau <holden@us.ibm.com>

Closes #11059 from holdenk/SPARK-13164-replace-deprecated-synchronized-buffer-in-core.

4 files changed, 40 insertions, 39 deletions

diff --git a/core/src/main/scala/org/apache/spark/ContextCleaner.scala b/core/src/main/scala/org/apache/spark/ContextCleaner.scala
index 5a42299a0b..17014e4954 100644
--- a/core/src/main/scala/org/apache/spark/ContextCleaner.scala
+++ b/core/src/main/scala/org/apache/spark/ContextCleaner.scala
@@ -18,9 +18,9 @@
 package org.apache.spark
 
 import java.lang.ref.{ReferenceQueue, WeakReference}
-import java.util.concurrent.{ScheduledExecutorService, TimeUnit}
+import java.util.concurrent.{ConcurrentLinkedQueue, ScheduledExecutorService, TimeUnit}
 
-import scala.collection.mutable.{ArrayBuffer, SynchronizedBuffer}
+import scala.collection.JavaConverters._
 
 import org.apache.spark.broadcast.Broadcast
 import org.apache.spark.rdd.{RDD, ReliableRDDCheckpointData}
@@ -57,13 +57,11 @@ private class CleanupTaskWeakReference(
  */
 private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
 
-  private val referenceBuffer = new ArrayBuffer[CleanupTaskWeakReference]
-    with SynchronizedBuffer[CleanupTaskWeakReference]
+  private val referenceBuffer = new ConcurrentLinkedQueue[CleanupTaskWeakReference]()
 
   private val referenceQueue = new ReferenceQueue[AnyRef]
 
-  private val listeners = new ArrayBuffer[CleanerListener]
-    with SynchronizedBuffer[CleanerListener]
+  private val listeners = new ConcurrentLinkedQueue[CleanerListener]()
 
   private val cleaningThread = new Thread() { override def run() { keepCleaning() }}
 
@@ -111,7 +109,7 @@ private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
 
   /** Attach a listener object to get information of when objects are cleaned. */
   def attachListener(listener: CleanerListener): Unit = {
-    listeners += listener
+    listeners.add(listener)
   }
 
   /** Start the cleaner. */
@@ -166,7 +164,7 @@ private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
 
   /** Register an object for cleanup. */
   private def registerForCleanup(objectForCleanup: AnyRef, task: CleanupTask): Unit = {
-    referenceBuffer += new CleanupTaskWeakReference(task, objectForCleanup, referenceQueue)
+    referenceBuffer.add(new CleanupTaskWeakReference(task, objectForCleanup, referenceQueue))
   }
 
   /** Keep cleaning RDD, shuffle, and broadcast state. */
@@ -179,7 +177,7 @@ private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
         synchronized {
           reference.map(_.task).foreach { task =>
             logDebug("Got cleaning task " + task)
-            referenceBuffer -= reference.get
+            referenceBuffer.remove(reference.get)
             task match {
               case CleanRDD(rddId) =>
                 doCleanupRDD(rddId, blocking = blockOnCleanupTasks)
@@ -206,7 +204,7 @@ private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
     try {
       logDebug("Cleaning RDD " + rddId)
       sc.unpersistRDD(rddId, blocking)
-      listeners.foreach(_.rddCleaned(rddId))
+      listeners.asScala.foreach(_.rddCleaned(rddId))
       logInfo("Cleaned RDD " + rddId)
     } catch {
       case e: Exception => logError("Error cleaning RDD " + rddId, e)
@@ -219,7 +217,7 @@ private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
       logDebug("Cleaning shuffle " + shuffleId)
       mapOutputTrackerMaster.unregisterShuffle(shuffleId)
       blockManagerMaster.removeShuffle(shuffleId, blocking)
-      listeners.foreach(_.shuffleCleaned(shuffleId))
+      listeners.asScala.foreach(_.shuffleCleaned(shuffleId))
       logInfo("Cleaned shuffle " + shuffleId)
     } catch {
       case e: Exception => logError("Error cleaning shuffle " + shuffleId, e)
@@ -231,7 +229,7 @@ private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
     try {
       logDebug(s"Cleaning broadcast $broadcastId")
       broadcastManager.unbroadcast(broadcastId, true, blocking)
-      listeners.foreach(_.broadcastCleaned(broadcastId))
+      listeners.asScala.foreach(_.broadcastCleaned(broadcastId))
       logDebug(s"Cleaned broadcast $broadcastId")
     } catch {
       case e: Exception => logError("Error cleaning broadcast " + broadcastId, e)
@@ -243,7 +241,7 @@ private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
     try {
       logDebug("Cleaning accumulator " + accId)
       Accumulators.remove(accId)
-      listeners.foreach(_.accumCleaned(accId))
+      listeners.asScala.foreach(_.accumCleaned(accId))
       logInfo("Cleaned accumulator " + accId)
     } catch {
       case e: Exception => logError("Error cleaning accumulator " + accId, e)
@@ -258,7 +256,7 @@ private[spark] class ContextCleaner(sc: SparkContext) extends Logging {
     try {
       logDebug("Cleaning rdd checkpoint data " + rddId)
       ReliableRDDCheckpointData.cleanCheckpoint(sc, rddId)
-      listeners.foreach(_.checkpointCleaned(rddId))
+      listeners.asScala.foreach(_.checkpointCleaned(rddId))
       logInfo("Cleaned rdd checkpoint data " + rddId)
     }
     catch {
diff --git a/core/src/test/scala/org/apache/spark/deploy/client/AppClientSuite.scala b/core/src/test/scala/org/apache/spark/deploy/client/AppClientSuite.scala
index eb794b6739..658779360b 100644
--- a/core/src/test/scala/org/apache/spark/deploy/client/AppClientSuite.scala
+++ b/core/src/test/scala/org/apache/spark/deploy/client/AppClientSuite.scala
@@ -17,7 +17,9 @@
 
 package org.apache.spark.deploy.client
 
-import scala.collection.mutable.{ArrayBuffer, SynchronizedBuffer}
+import java.util.concurrent.ConcurrentLinkedQueue
+
+import scala.collection.JavaConverters._
 import scala.concurrent.duration._
 
 import org.scalatest.BeforeAndAfterAll
@@ -165,14 +167,14 @@ class AppClientSuite extends SparkFunSuite with LocalSparkContext with BeforeAnd
 
   /** Application Listener to collect events */
   private class AppClientCollector extends AppClientListener with Logging {
-    val connectedIdList = new ArrayBuffer[String] with SynchronizedBuffer[String]
+    val connectedIdList = new ConcurrentLinkedQueue[String]()
     @volatile var disconnectedCount: Int = 0
-    val deadReasonList = new ArrayBuffer[String] with SynchronizedBuffer[String]
-    val execAddedList = new ArrayBuffer[String] with SynchronizedBuffer[String]
-    val execRemovedList = new ArrayBuffer[String] with SynchronizedBuffer[String]
+    val deadReasonList = new ConcurrentLinkedQueue[String]()
+    val execAddedList = new ConcurrentLinkedQueue[String]()
+    val execRemovedList = new ConcurrentLinkedQueue[String]()
 
     def connected(id: String): Unit = {
-      connectedIdList += id
+      connectedIdList.add(id)
     }
 
     def disconnected(): Unit = {
@@ -182,7 +184,7 @@ class AppClientSuite extends SparkFunSuite with LocalSparkContext with BeforeAnd
     }
 
     def dead(reason: String): Unit = {
-      deadReasonList += reason
+      deadReasonList.add(reason)
     }
 
     def executorAdded(
@@ -191,11 +193,11 @@ class AppClientSuite extends SparkFunSuite with LocalSparkContext with BeforeAnd
         hostPort: String,
         cores: Int,
         memory: Int): Unit = {
-      execAddedList += id
+      execAddedList.add(id)
     }
 
     def executorRemoved(id: String, message: String, exitStatus: Option[Int]): Unit = {
-      execRemovedList += id
+      execRemovedList.add(id)
     }
   }
 
diff --git a/core/src/test/scala/org/apache/spark/rpc/RpcEnvSuite.scala b/core/src/test/scala/org/apache/spark/rpc/RpcEnvSuite.scala
index 6f4eda8b47..2204800388 100644
--- a/core/src/test/scala/org/apache/spark/rpc/RpcEnvSuite.scala
+++ b/core/src/test/scala/org/apache/spark/rpc/RpcEnvSuite.scala
@@ -20,9 +20,10 @@ package org.apache.spark.rpc
 import java.io.{File, NotSerializableException}
 import java.nio.charset.StandardCharsets.UTF_8
 import java.util.UUID
-import java.util.concurrent.{CountDownLatch, TimeoutException, TimeUnit}
+import java.util.concurrent.{ConcurrentLinkedQueue, CountDownLatch, TimeoutException, TimeUnit}
 
 import scala.collection.mutable
+import scala.collection.JavaConverters._
 import scala.concurrent.Await
 import scala.concurrent.duration._
 import scala.language.postfixOps
@@ -490,30 +491,30 @@ abstract class RpcEnvSuite extends SparkFunSuite with BeforeAndAfterAll {
 
   /**
    * Setup an [[RpcEndpoint]] to collect all network events.
-   * @return the [[RpcEndpointRef]] and an `Seq` that contains network events.
+   * @return the [[RpcEndpointRef]] and an `ConcurrentLinkedQueue` that contains network events.
    */
   private def setupNetworkEndpoint(
       _env: RpcEnv,
-      name: String): (RpcEndpointRef, Seq[(Any, Any)]) = {
-    val events = new mutable.ArrayBuffer[(Any, Any)] with mutable.SynchronizedBuffer[(Any, Any)]
+      name: String): (RpcEndpointRef, ConcurrentLinkedQueue[(Any, Any)]) = {
+    val events = new ConcurrentLinkedQueue[(Any, Any)]
     val ref = _env.setupEndpoint("network-events-non-client", new ThreadSafeRpcEndpoint {
       override val rpcEnv = _env
 
       override def receive: PartialFunction[Any, Unit] = {
         case "hello" =>
-        case m => events += "receive" -> m
+        case m => events.add("receive" -> m)
       }
 
       override def onConnected(remoteAddress: RpcAddress): Unit = {
-        events += "onConnected" -> remoteAddress
+        events.add("onConnected" -> remoteAddress)
       }
 
       override def onDisconnected(remoteAddress: RpcAddress): Unit = {
-        events += "onDisconnected" -> remoteAddress
+        events.add("onDisconnected" -> remoteAddress)
       }
 
       override def onNetworkError(cause: Throwable, remoteAddress: RpcAddress): Unit = {
-        events += "onNetworkError" -> remoteAddress
+        events.add("onNetworkError" -> remoteAddress)
       }
 
     })
@@ -560,7 +561,7 @@ abstract class RpcEnvSuite extends SparkFunSuite with BeforeAndAfterAll {
 
       eventually(timeout(5 seconds), interval(5 millis)) {
         // We don't know the exact client address but at least we can verify the message type
-        assert(events.map(_._1).contains("onConnected"))
+        assert(events.asScala.map(_._1).exists(_ == "onConnected"))
       }
 
       clientEnv.shutdown()
@@ -568,8 +569,8 @@ abstract class RpcEnvSuite extends SparkFunSuite with BeforeAndAfterAll {
 
       eventually(timeout(5 seconds), interval(5 millis)) {
         // We don't know the exact client address but at least we can verify the message type
-        assert(events.map(_._1).contains("onConnected"))
-        assert(events.map(_._1).contains("onDisconnected"))
+        assert(events.asScala.map(_._1).exists(_ == "onConnected"))
+        assert(events.asScala.map(_._1).exists(_ == "onDisconnected"))
       }
     } finally {
       clientEnv.shutdown()
diff --git a/core/src/test/scala/org/apache/spark/util/EventLoopSuite.scala b/core/src/test/scala/org/apache/spark/util/EventLoopSuite.scala
index b207d497f3..6f7dddd4f7 100644
--- a/core/src/test/scala/org/apache/spark/util/EventLoopSuite.scala
+++ b/core/src/test/scala/org/apache/spark/util/EventLoopSuite.scala
@@ -17,9 +17,9 @@
 
 package org.apache.spark.util
 
-import java.util.concurrent.CountDownLatch
+import java.util.concurrent.{ConcurrentLinkedQueue, CountDownLatch}
 
-import scala.collection.mutable
+import scala.collection.JavaConverters._
 import scala.concurrent.duration._
 import scala.language.postfixOps
 
@@ -31,11 +31,11 @@ import org.apache.spark.SparkFunSuite
 class EventLoopSuite extends SparkFunSuite with Timeouts {
 
   test("EventLoop") {
-    val buffer = new mutable.ArrayBuffer[Int] with mutable.SynchronizedBuffer[Int]
+    val buffer = new ConcurrentLinkedQueue[Int]
     val eventLoop = new EventLoop[Int]("test") {
 
       override def onReceive(event: Int): Unit = {
-        buffer += event
+        buffer.add(event)
       }
 
       override def onError(e: Throwable): Unit = {}
@@ -43,7 +43,7 @@ class EventLoopSuite extends SparkFunSuite with Timeouts {
     eventLoop.start()
     (1 to 100).foreach(eventLoop.post)
     eventually(timeout(5 seconds), interval(5 millis)) {
-      assert((1 to 100) === buffer.toSeq)
+      assert((1 to 100) === buffer.asScala.toSeq)
     }
     eventLoop.stop()
   }