Merge branch 'master' into profiler

Conflicts:
	docs/configuration.md

Author: davies

core/src/main/scala/org/apache/spark/SparkEnv.scala

@@ -108,6 +108,14 @@ class SparkEnv (
       pythonWorkers.get(key).foreach(_.stopWorker(worker))
     }
   }
+
+  private[spark]
+  def releasePythonWorker(pythonExec: String, envVars: Map[String, String], worker: Socket) {
+    synchronized {
+      val key = (pythonExec, envVars)
+      pythonWorkers.get(key).foreach(_.releaseWorker(worker))
+    }
+  }
 }
 
 object SparkEnv extends Logging {

core/src/main/scala/org/apache/spark/TaskContext.scala

@@ -21,7 +21,7 @@ import scala.collection.mutable.ArrayBuffer
 
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.executor.TaskMetrics
-import org.apache.spark.util.TaskCompletionListener
+import org.apache.spark.util.{TaskCompletionListenerException, TaskCompletionListener}
 
 
 /**
@@ -41,7 +41,7 @@ class TaskContext(
     val attemptId: Long,
     val runningLocally: Boolean = false,
     private[spark] val taskMetrics: TaskMetrics = TaskMetrics.empty)
-  extends Serializable {
+  extends Serializable with Logging {
 
   @deprecated("use partitionId", "0.8.1")
   def splitId = partitionId
@@ -103,8 +103,20 @@ class TaskContext(
   /** Marks the task as completed and triggers the listeners. */
   private[spark] def markTaskCompleted(): Unit = {
     completed = true
+    val errorMsgs = new ArrayBuffer[String](2)
     // Process complete callbacks in the reverse order of registration
-    onCompleteCallbacks.reverse.foreach { _.onTaskCompletion(this) }
+    onCompleteCallbacks.reverse.foreach { listener =>
+      try {
+        listener.onTaskCompletion(this)
+      } catch {
+        case e: Throwable =>
+          errorMsgs += e.getMessage
+          logError("Error in TaskCompletionListener", e)
+      }
+    }
+    if (errorMsgs.nonEmpty) {
+      throw new TaskCompletionListenerException(errorMsgs)
+    }
   }
 
   /** Marks the task for interruption, i.e. cancellation. */

core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala

@@ -17,6 +17,7 @@
 
 package org.apache.spark.api.java
 
+import java.io.Closeable
 import java.util
 import java.util.{Map => JMap}
 
@@ -40,7 +41,9 @@ import org.apache.spark.rdd.{EmptyRDD, HadoopRDD, NewHadoopRDD, RDD}
  * A Java-friendly version of [[org.apache.spark.SparkContext]] that returns
  * [[org.apache.spark.api.java.JavaRDD]]s and works with Java collections instead of Scala ones.
  */
-class JavaSparkContext(val sc: SparkContext) extends JavaSparkContextVarargsWorkaround {
+class JavaSparkContext(val sc: SparkContext)
+  extends JavaSparkContextVarargsWorkaround with Closeable {
+
   /**
    * Create a JavaSparkContext that loads settings from system properties (for instance, when
    * launching with ./bin/spark-submit).
@@ -534,6 +537,8 @@ class JavaSparkContext(val sc: SparkContext) extends JavaSparkContextVarargsWork
     sc.stop()
   }
 
+  override def close(): Unit = stop()
+
   /**
    * Get Spark's home location from either a value set through the constructor,
    * or the spark.home Java property, or the SPARK_HOME environment variable

core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala

@@ -23,6 +23,7 @@ import java.nio.charset.Charset
 import java.util.{List => JList, ArrayList => JArrayList, Map => JMap, Collections}
 
 import scala.collection.JavaConversions._
+import scala.collection.mutable
 import scala.language.existentials
 import scala.reflect.ClassTag
 import scala.util.{Try, Success, Failure}
@@ -52,6 +53,7 @@ private[spark] class PythonRDD(
   extends RDD[Array[Byte]](parent) {
 
   val bufferSize = conf.getInt("spark.buffer.size", 65536)
+  val reuse_worker = conf.getBoolean("spark.python.worker.reuse", true)
 
   override def getPartitions = parent.partitions
 
@@ -63,19 +65,26 @@ private[spark] class PythonRDD(
     val localdir = env.blockManager.diskBlockManager.localDirs.map(
       f => f.getPath()).mkString(",")
     envVars += ("SPARK_LOCAL_DIRS" -> localdir) // it's also used in monitor thread
+    if (reuse_worker) {
+      envVars += ("SPARK_REUSE_WORKER" -> "1")
+    }
     val worker: Socket = env.createPythonWorker(pythonExec, envVars.toMap)
 
     // Start a thread to feed the process input from our parent's iterator
     val writerThread = new WriterThread(env, worker, split, context)
 
+    var complete_cleanly = false
     context.addTaskCompletionListener { context =>
       writerThread.shutdownOnTaskCompletion()
-
-      // Cleanup the worker socket. This will also cause the Python worker to exit.
-      try {
-        worker.close()
-      } catch {
-        case e: Exception => logWarning("Failed to close worker socket", e)
+      if (reuse_worker && complete_cleanly) {
+        env.releasePythonWorker(pythonExec, envVars.toMap, worker)
+      } else {
+        try {
+          worker.close()
+        } catch {
+          case e: Exception =>
+            logWarning("Failed to close worker socket", e)
+        }
       }
     }
 
@@ -133,6 +142,7 @@ private[spark] class PythonRDD(
                 stream.readFully(update)
                 accumulator += Collections.singletonList(update)
               }
+               complete_cleanly = true
               null
           }
         } catch {
@@ -195,29 +205,45 @@ private[spark] class PythonRDD(
           PythonRDD.writeUTF(include, dataOut)
         }
         // Broadcast variables
-        dataOut.writeInt(broadcastVars.length)
+        val oldBids = PythonRDD.getWorkerBroadcasts(worker)
+        val newBids = broadcastVars.map(_.id).toSet
+        // number of different broadcasts
+        val cnt = oldBids.diff(newBids).size + newBids.diff(oldBids).size
+        dataOut.writeInt(cnt)
+        for (bid <- oldBids) {
+          if (!newBids.contains(bid)) {
+            // remove the broadcast from worker
+            dataOut.writeLong(- bid - 1)  // bid >= 0
+            oldBids.remove(bid)
+          }
+        }
         for (broadcast <- broadcastVars) {
-          dataOut.writeLong(broadcast.id)
-          dataOut.writeInt(broadcast.value.length)
-          dataOut.write(broadcast.value)
+          if (!oldBids.contains(broadcast.id)) {
+            // send new broadcast
+            dataOut.writeLong(broadcast.id)
+            dataOut.writeInt(broadcast.value.length)
+            dataOut.write(broadcast.value)
+            oldBids.add(broadcast.id)
+          }
         }
         dataOut.flush()
         // Serialized command:
         dataOut.writeInt(command.length)
         dataOut.write(command)
         // Data values
         PythonRDD.writeIteratorToStream(parent.iterator(split, context), dataOut)
+        dataOut.writeInt(SpecialLengths.END_OF_DATA_SECTION)
         dataOut.flush()
       } catch {
         case e: Exception if context.isCompleted || context.isInterrupted =>
           logDebug("Exception thrown after task completion (likely due to cleanup)", e)
+          worker.shutdownOutput()
 
         case e: Exception =>
           // We must avoid throwing exceptions here, because the thread uncaught exception handler
           // will kill the whole executor (see org.apache.spark.executor.Executor).
           _exception = e
-      } finally {
-        Try(worker.shutdownOutput()) // kill Python worker process
+          worker.shutdownOutput()
       }
     }
   }
@@ -278,6 +304,14 @@ private object SpecialLengths {
 private[spark] object PythonRDD extends Logging {
   val UTF8 = Charset.forName("UTF-8")
 
+  // remember the broadcasts sent to each worker
+  private val workerBroadcasts = new mutable.WeakHashMap[Socket, mutable.Set[Long]]()
+  private def getWorkerBroadcasts(worker: Socket) = {
+    synchronized {
+      workerBroadcasts.getOrElseUpdate(worker, new mutable.HashSet[Long]())
+    }
+  }
+
   /**
    * Adapter for calling SparkContext#runJob from Python.
    *

core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala

@@ -40,7 +40,10 @@ private[spark] class PythonWorkerFactory(pythonExec: String, envVars: Map[String
   var daemon: Process = null
   val daemonHost = InetAddress.getByAddress(Array(127, 0, 0, 1))
   var daemonPort: Int = 0
-  var daemonWorkers = new mutable.WeakHashMap[Socket, Int]()
+  val daemonWorkers = new mutable.WeakHashMap[Socket, Int]()
+  val idleWorkers = new mutable.Queue[Socket]()
+  var lastActivity = 0L
+  new MonitorThread().start()
 
   var simpleWorkers = new mutable.WeakHashMap[Socket, Process]()
 
@@ -51,6 +54,11 @@ private[spark] class PythonWorkerFactory(pythonExec: String, envVars: Map[String
 
   def create(): Socket = {
     if (useDaemon) {
+      synchronized {
+        if (idleWorkers.size > 0) {
+          return idleWorkers.dequeue()
+        }
+      }
       createThroughDaemon()
     } else {
       createSimpleWorker()
@@ -199,9 +207,44 @@ private[spark] class PythonWorkerFactory(pythonExec: String, envVars: Map[String
     }
   }
 
+  /**
+   * Monitor all the idle workers, kill them after timeout.
+   */
+  private class MonitorThread extends Thread(s"Idle Worker Monitor for $pythonExec") {
+
+    setDaemon(true)
+
+    override def run() {
+      while (true) {
+        synchronized {
+          if (lastActivity + IDLE_WORKER_TIMEOUT_MS < System.currentTimeMillis()) {
+            cleanupIdleWorkers()
+            lastActivity = System.currentTimeMillis()
+          }
+        }
+        Thread.sleep(10000)
+      }
+    }
+  }
+
+  private def cleanupIdleWorkers() {
+    while (idleWorkers.length > 0) {
+      val worker = idleWorkers.dequeue()
+      try {
+        // the worker will exit after closing the socket
+        worker.close()
+      } catch {
+        case e: Exception =>
+          logWarning("Failed to close worker socket", e)
+      }
+    }
+  }
+
   private def stopDaemon() {
     synchronized {
       if (useDaemon) {
+        cleanupIdleWorkers()
+
         // Request shutdown of existing daemon by sending SIGTERM
         if (daemon != null) {
           daemon.destroy()
@@ -220,23 +263,43 @@ private[spark] class PythonWorkerFactory(pythonExec: String, envVars: Map[String
   }
 
   def stopWorker(worker: Socket) {
-    if (useDaemon) {
-      if (daemon != null) {
-        daemonWorkers.get(worker).foreach { pid =>
-          // tell daemon to kill worker by pid
-          val output = new DataOutputStream(daemon.getOutputStream)
-          output.writeInt(pid)
-          output.flush()
-          daemon.getOutputStream.flush()
+    synchronized {
+      if (useDaemon) {
+        if (daemon != null) {
+          daemonWorkers.get(worker).foreach { pid =>
+            // tell daemon to kill worker by pid
+            val output = new DataOutputStream(daemon.getOutputStream)
+            output.writeInt(pid)
+            output.flush()
+            daemon.getOutputStream.flush()
+          }
         }
+      } else {
+        simpleWorkers.get(worker).foreach(_.destroy())
       }
-    } else {
-      simpleWorkers.get(worker).foreach(_.destroy())
     }
     worker.close()
   }
+
+  def releaseWorker(worker: Socket) {
+    if (useDaemon) {
+      synchronized {
+        lastActivity = System.currentTimeMillis()
+        idleWorkers.enqueue(worker)
+      }
+    } else {
+      // Cleanup the worker socket. This will also cause the Python worker to exit.
+      try {
+        worker.close()
+      } catch {
+        case e: Exception =>
+          logWarning("Failed to close worker socket", e)
+      }
+    }
+  }
 }
 
 private object PythonWorkerFactory {
   val PROCESS_WAIT_TIMEOUT_MS = 10000
+  val IDLE_WORKER_TIMEOUT_MS = 60000  // kill idle workers after 1 minute
 }

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

@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.util
+
+/**
+ * Exception thrown when there is an exception in
+ * executing the callback in TaskCompletionListener.
+ */
+private[spark]
+class TaskCompletionListenerException(errorMessages: Seq[String]) extends Exception {
+
+  override def getMessage: String = {
+    if (errorMessages.size == 1) {
+      errorMessages.head
+    } else {
+      errorMessages.zipWithIndex.map { case (msg, i) => s"Exception $i: $msg" }.mkString("\n")
+    }
+  }
+}