我是spark的新手，最近我在mesos上部署了我的第一个spark星团。
当我使用python开发应用程序时，我尝试在集群上运行示例pi。结果显示成功，但我得到以下警告。

16/10/18 17:28:54 WARN NettyRpcEndpointRef: Error sending message [message = RemoveExecutor(1,Executor finished with state FINISHED)] in 1 attempts
org.apache.spark.SparkException: Exception thrown in awaitResult
    at org.apache.spark.rpc.RpcTimeout$$anonfun$1.applyOrElse(RpcTimeout.scala:77)
    at org.apache.spark.rpc.RpcTimeout$$anonfun$1.applyOrElse(RpcTimeout.scala:75)
    at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:36)
    at org.apache.spark.rpc.RpcTimeout$$anonfun$addMessageIfTimeout$1.applyOrElse(RpcTimeout.scala:59)
    at org.apache.spark.rpc.RpcTimeout$$anonfun$addMessageIfTimeout$1.applyOrElse(RpcTimeout.scala:59)
    at scala.PartialFunction$OrElse.apply(PartialFunction.scala:167)
    at org.apache.spark.rpc.RpcTimeout.awaitResult(RpcTimeout.scala:83)
    at org.apache.spark.rpc.RpcEndpointRef.askWithRetry(RpcEndpointRef.scala:102)
    at org.apache.spark.rpc.RpcEndpointRef.askWithRetry(RpcEndpointRef.scala:78)
    at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend.removeExecutor(CoarseGrainedSchedulerBackend.scala:412)
    at org.apache.spark.scheduler.cluster.mesos.MesosCoarseGrainedSchedulerBackend.executorTerminated(MesosCoarseGrainedSchedulerBackend.scala:555)
    at org.apache.spark.scheduler.cluster.mesos.MesosCoarseGrainedSchedulerBackend.statusUpdate(MesosCoarseGrainedSchedulerBackend.scala:495)
Caused by: org.apache.spark.SparkException: Could not find CoarseGrainedScheduler.
    at org.apache.spark.rpc.netty.Dispatcher.postMessage(Dispatcher.scala:152)
    at org.apache.spark.rpc.netty.Dispatcher.postLocalMessage(Dispatcher.scala:127)
    at org.apache.spark.rpc.netty.NettyRpcEnv.ask(NettyRpcEnv.scala:225)
    at org.apache.spark.rpc.netty.NettyRpcEndpointRef.ask(NettyRpcEnv.scala:508)
    at org.apache.spark.rpc.RpcEndpointRef.askWithRetry(RpcEndpointRef.scala:101)
    ... 4 more

还有一个工人被杀的情况。
我就是这样提交申请的

$SPARK_HOME/bin/spark-submit --master mesos://<MESOS_HOST>:<MESOS_PORT> $SPARK_HOME/examples/src/main/python/pi.py 1000

谁能给我一些建议吗？提前谢谢！