title: Spark and Java: Exception thrown in awaitResult
body: <p>I am trying to connect a Spark cluster running within a virtual machine with IP <code>10.20.30.50</code> and port <code>7077</code> from within a Java application and run the word count example:</p>
  
  <pre><code>SparkConf conf = new SparkConf().setMaster("spark://10.20.30.50:7077").setAppName("wordCount");
  JavaSparkContext sc = new JavaSparkContext(conf);
  JavaRDD&lt;String&gt; textFile = sc.textFile("hdfs://localhost:8020/README.md");
  String result = Long.toString(textFile.count());
  JavaRDD&lt;String&gt; words = textFile.flatMap((FlatMapFunction&lt;String, String&gt;) s -&gt; Arrays.asList(s.split(" ")).iterator());
  JavaPairRDD&lt;String, Integer&gt; pairs = words.mapToPair((PairFunction&lt;String, String, Integer&gt;) s -&gt; new Tuple2&lt;&gt;(s, 1));
  JavaPairRDD&lt;String, Integer&gt; counts = pairs.reduceByKey((Function2&lt;Integer, Integer, Integer&gt;) (a, b) -&gt; a + b);
  counts.saveAsTextFile("hdfs://localhost:8020/tmp/output");
  sc.stop();
  return result;
  </code></pre>
  
  <p>The Java application shows the following stack trace:</p>
  
  <pre><code>Running Spark version 2.0.1
  Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
  Changing view acls to: lii5ka
  Changing modify acls to: lii5ka
  Changing view acls groups to:
  Changing modify acls groups to:
  SecurityManager: authentication disabled; ui acls disabled; users  with view permissions: Set(lii5ka); groups with view permissions: Set(); users  with modify permissions: Set(lii5ka); groups with modify permissions: Set()
  Successfully started service 'sparkDriver' on port 61267.
  Registering MapOutputTracker
  Registering BlockManagerMaster
  Created local directory at /private/var/folders/4k/h0sl02993_99bzt0dzv759000000gn/T/blockmgr-51de868d-3ba7-40be-8c53-f881f97ced63
  MemoryStore started with capacity 2004.6 MB
  Registering OutputCommitCoordinator
  Logging initialized @48403ms
  jetty-9.2.z-SNAPSHOT
  Started o.s.j.s.ServletContextHandler@1316e7ec{/jobs,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@782de006{/jobs/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@2d0353{/jobs/job,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@381e24a0{/jobs/job/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@1c138dc8{/stages,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@b29739c{/stages/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@63f6de31{/stages/stage,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@2a04ddcb{/stages/stage/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@2af9688e{/stages/pool,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@6a0c5bde{/stages/pool/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@3f5e17f8{/storage,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@33b86f5d{/storage/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@5264dcbc{/storage/rdd,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@5a3ebf85{/storage/rdd/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@159082ed{/environment,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@6522c585{/environment/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@115774a1{/executors,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@3e3a3399{/executors/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@2f2c5959{/executors/threadDump,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@5c51afd4{/executors/threadDump/json,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@76893a83{/static,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@19c07930{/,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@54eb0dc0{/api,null,AVAILABLE}
  Started o.s.j.s.ServletContextHandler@5953786{/stages/stage/kill,null,AVAILABLE}
  Started ServerConnector@2eeb8bd6{HTTP/1.1}{0.0.0.0:4040}
  Started @48698ms
  Successfully started service 'SparkUI' on port 4040.
  Bound SparkUI to 0.0.0.0, and started at http://192.168.0.104:4040
  Connecting to master spark://10.20.30.50:7077...
  Successfully created connection to /10.20.30.50:7077 after 25 ms (0 ms spent in bootstraps)
  Connecting to master spark://10.20.30.50:7077...
  Still have 2 requests outstanding when connection from /10.20.30.50:7077 is closed
  Failed to connect to master 10.20.30.50:7077
  
  org.apache.spark.SparkException: Exception thrown in awaitResult
          at org.apache.spark.rpc.RpcTimeout$$anonfun$1.applyOrElse(RpcTimeout.scala:77) ~[spark-core_2.11-2.0.1.jar:2.0.1]
          at org.apache.spark.rpc.RpcTimeout$$anonfun$1.applyOrElse(RpcTimeout.scala:75) ~[spark-core_2.11-2.0.1.jar:2.0.1]
          at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:36) ~[scala-library-2.11.8.jar:na]
          at org.apache.spark.rpc.RpcTimeout$$anonfun$addMessageIfTimeout$1.applyOrElse(RpcTimeout.scala:59) ~[spark-core_2.11-2.0.1.jar:2.0.1]
          at org.apache.spark.rpc.RpcTimeout$$anonfun$addMessageIfTimeout$1.applyOrElse(RpcTimeout.scala:59) ~[spark-core_2.11-2.0.1.jar:2.0.1]
          at scala.PartialFunction$OrElse.apply(PartialFunction.scala:167) ~[scala-library-2.11.8.jar:na]
          at org.apache.spark.rpc.RpcTimeout.awaitResult(RpcTimeout.scala:83) ~[spark-core_2.11-2.0.1.jar:2.0.1]
          at org.apache.spark.rpc.RpcEnv.setupEndpointRefByURI(RpcEnv.scala:88) ~[spark-core_2.11-2.0.1.jar:2.0.1]
          at org.apache.spark.rpc.RpcEnv.setupEndpointRef(RpcEnv.scala:96) ~[spark-core_2.11-2.0.1.jar:2.0.1]
          at org.apache.spark.deploy.client.StandaloneAppClient$ClientEndpoint$$anonfun$tryRegisterAllMasters$1$$anon$1.run(StandaloneAppClient.scala:106) ~[spark-core_2.11-2.0.1.jar:2.0.1]
          at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_102]
          at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_102]
          at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_102]
          at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_102]
          at java.lang.Thread.run(Thread.java:745) [na:1.8.0_102]
  Caused by: java.io.IOException: Connection from /10.20.30.50:7077 closed
          at org.apache.spark.network.client.TransportResponseHandler.channelInactive(TransportResponseHandler.java:128) ~[spark-network-common_2.11-2.0.1.jar:2.0.1]
          at org.apache.spark.network.server.TransportChannelHandler.channelInactive(TransportChannelHandler.java:109) ~[spark-network-common_2.11-2.0.1.jar:2.0.1]
          at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:208) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:194) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:75) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.handler.timeout.IdleStateHandler.channelInactive(IdleStateHandler.java:257) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:208) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:194) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:75) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:208) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:194) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:75) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at org.apache.spark.network.util.TransportFrameDecoder.channelInactive(TransportFrameDecoder.java:182) ~[spark-network-common_2.11-2.0.1.jar:2.0.1]
          at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:208) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:194) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.DefaultChannelPipeline.fireChannelInactive(DefaultChannelPipeline.java:828) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.AbstractChannel$AbstractUnsafe$7.run(AbstractChannel.java:621) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:357) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:357) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111) ~[netty-all-4.0.29.Final.jar:4.0.29.Final]
          ... 1 common frames omitted
  </code></pre>
  
  <p>In the Spark Master log on <code>10.20.30.50</code>, I get the following error message:</p>
  
  <pre><code>16/11/05 14:47:20 ERROR OneForOneStrategy: Error while decoding incoming Akka PDU of length: 1298
  akka.remote.transport.AkkaProtocolException: Error while decoding incoming Akka PDU of length: 1298
  Caused by: akka.remote.transport.PduCodecException: Decoding PDU failed.
      at akka.remote.transport.AkkaPduProtobufCodec$.decodePdu(AkkaPduCodec.scala:167)
      at akka.remote.transport.ProtocolStateActor.akka$remote$transport$ProtocolStateActor$$decodePdu(AkkaProtocolTransport.scala:580)
      at akka.remote.transport.ProtocolStateActor$$anonfun$4.applyOrElse(AkkaProtocolTransport.scala:375)
      at akka.remote.transport.ProtocolStateActor$$anonfun$4.applyOrElse(AkkaProtocolTransport.scala:343)
      at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:33)
      at akka.actor.FSM$class.processEvent(FSM.scala:604)
      at akka.remote.transport.ProtocolStateActor.processEvent(AkkaProtocolTransport.scala:269)
      at akka.actor.FSM$class.akka$actor$FSM$$processMsg(FSM.scala:598)
      at akka.actor.FSM$$anonfun$receive$1.applyOrElse(FSM.scala:592)
      at akka.actor.Actor$class.aroundReceive(Actor.scala:467)
      at akka.remote.transport.ProtocolStateActor.aroundReceive(AkkaProtocolTransport.scala:269)
      at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516)
      at akka.actor.ActorCell.invoke(ActorCell.scala:487)
      at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:238)
      at akka.dispatch.Mailbox.run(Mailbox.scala:220)
      at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:397)
      at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
      at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
      at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
      at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
  Caused by: com.google.protobuf.InvalidProtocolBufferException: Protocol message contained an invalid tag (zero).
      at com.google.protobuf.InvalidProtocolBufferException.invalidTag(InvalidProtocolBufferException.java:89)
      at com.google.protobuf.CodedInputStream.readTag(CodedInputStream.java:108)
      at akka.remote.WireFormats$AkkaProtocolMessage.&lt;init&gt;(WireFormats.java:6643)
      at akka.remote.WireFormats$AkkaProtocolMessage.&lt;init&gt;(WireFormats.java:6607)
      at akka.remote.WireFormats$AkkaProtocolMessage$1.parsePartialFrom(WireFormats.java:6703)
      at akka.remote.WireFormats$AkkaProtocolMessage$1.parsePartialFrom(WireFormats.java:6698)
      at com.google.protobuf.AbstractParser.parsePartialFrom(AbstractParser.java:141)
      at com.google.protobuf.AbstractParser.parseFrom(AbstractParser.java:176)
      at com.google.protobuf.AbstractParser.parseFrom(AbstractParser.java:188)
      at com.google.protobuf.AbstractParser.parseFrom(AbstractParser.java:193)
      at com.google.protobuf.AbstractParser.parseFrom(AbstractParser.java:49)
      at akka.remote.WireFormats$AkkaProtocolMessage.parseFrom(WireFormats.java:6821)
      at akka.remote.transport.AkkaPduProtobufCodec$.decodePdu(AkkaPduCodec.scala:168)
      ... 19 more
  </code></pre>
  
  <p><strong>Additional Information</strong></p>
  
  <ul>
  <li>The example works fine when I use <code>new SparkConf().setMaster("local")</code> instead</li>
  <li>I can connect to the Spark Master with <code>spark-shell --master spark://10.20.30.50:7077</code> on the very same machine</li>
  </ul>