title: Spark concurrently jobs fail
body: <p>If I run a single job with spark on yarn-client everything works fine, but on multiple (>1) concurrently jobs I get the following exception on the container nodes. I'm Using Spark 1.2 with CDH5.3 and Spark-Jobserver</p>
  
  <pre><code>java.io.IOException: org.apache.spark.SparkException: Failed to get broadcast_3_piece0 of broadcast_3
      at org.apache.spark.util.Utils$.tryOrIOException(Utils.scala:1011)
      at org.apache.spark.broadcast.TorrentBroadcast.readBroadcastBlock(TorrentBroadcast.scala:164)
      at org.apache.spark.broadcast.TorrentBroadcast._value$lzycompute(TorrentBroadcast.scala:64)
      at org.apache.spark.broadcast.TorrentBroadcast._value(TorrentBroadcast.scala:64)
      at org.apache.spark.broadcast.TorrentBroadcast.getValue(TorrentBroadcast.scala:87)
      at org.apache.spark.broadcast.Broadcast.value(Broadcast.scala:70)
      at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:58)
      at org.apache.spark.scheduler.Task.run(Task.scala:56)
      at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:196)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
      at java.lang.Thread.run(Thread.java:745)
  Caused by: org.apache.spark.SparkException: Failed to get broadcast_3_piece0 of broadcast_3
      at org.apache.spark.broadcast.TorrentBroadcast$$anonfun$org$apache$spark$broadcast$TorrentBroadcast$$readBlocks$1$$anonfun$2.apply(TorrentBroadcast.scala:137)
      at org.apache.spark.broadcast.TorrentBroadcast$$anonfun$org$apache$spark$broadcast$TorrentBroadcast$$readBlocks$1$$anonfun$2.apply(TorrentBroadcast.scala:137)
      at scala.Option.getOrElse(Option.scala:120)
      at org.apache.spark.broadcast.TorrentBroadcast$$anonfun$org$apache$spark$broadcast$TorrentBroadcast$$readBlocks$1.apply$mcVI$sp(TorrentBroadcast.scala:136)
      at org.apache.spark.broadcast.TorrentBroadcast$$anonfun$org$apache$spark$broadcast$TorrentBroadcast$$readBlocks$1.apply(TorrentBroadcast.scala:119)
      at org.apache.spark.broadcast.TorrentBroadcast$$anonfun$org$apache$spark$broadcast$TorrentBroadcast$$readBlocks$1.apply(TorrentBroadcast.scala:119)
      at scala.collection.immutable.List.foreach(List.scala:318)
      at org.apache.spark.broadcast.TorrentBroadcast.org$apache$spark$broadcast$TorrentBroadcast$$readBlocks(TorrentBroadcast.scala:119)
      at org.apache.spark.broadcast.TorrentBroadcast$$anonfun$readBroadcastBlock$1.apply(TorrentBroadcast.scala:174)
      at org.apache.spark.util.Utils$.tryOrIOException(Utils.scala:1008)
      ... 11 more
  15/02/02 19:20:17 INFO executor.CoarseGrainedExecutorBackend: Got assigned task 1
  15/02/02 19:20:17 INFO executor.Executor: Running task 1.0 in stage 0.0 (TID 1)
  15/02/02 19:20:17 INFO broadcast.TorrentBroadcast: Started reading broadcast variable 3
  15/02/02 19:20:17 ERROR executor.Executor: Exception in task 1.0 in stage 0.0 (TID 1)
  </code></pre>