title: Error while submitting a spark job using spark-jobserver
body: <p>I face following error occasionally while submitting job. This error goes away if I remove the rootdir of filedao, datadao and sqldao. That means I have to restart the job-server and re-upload my jar.</p>
  
  <pre><code>{
    "status": "ERROR",
    "result": {
      "message": "Ask timed out on [Actor[akka://JobServer/user/context-supervisor/1995aeba-com.spmsoftware.distributed.job.TestJob#-1370794810]] after [10000 ms]. Sender[null] sent message of type \"spark.jobserver.JobManagerActor$StartJob\".",
      "errorClass": "akka.pattern.AskTimeoutException",
      "stack": ["akka.pattern.PromiseActorRef$$anonfun$1.apply$mcV$sp(AskSupport.scala:604)", "akka.actor.Scheduler$$anon$4.run(Scheduler.scala:126)", "scala.concurrent.Future$InternalCallbackExecutor$.unbatchedExecute(Future.scala:601)", "scala.concurrent.BatchingExecutor$class.execute(BatchingExecutor.scala:109)", "scala.concurrent.Future$InternalCallbackExecutor$.execute(Future.scala:599)", "akka.actor.LightArrayRevolverScheduler$TaskHolder.executeTask(LightArrayRevolverScheduler.scala:331)", "akka.actor.LightArrayRevolverScheduler$$anon$4.executeBucket$1(LightArrayRevolverScheduler.scala:282)", "akka.actor.LightArrayRevolverScheduler$$anon$4.nextTick(LightArrayRevolverScheduler.scala:286)", "akka.actor.LightArrayRevolverScheduler$$anon$4.run(LightArrayRevolverScheduler.scala:238)", "java.lang.Thread.run(Thread.java:745)"]
    }
  }
  </code></pre>
  
  <p>My config file is as follows:</p>
  
  <pre><code># Template for a Spark Job Server configuration file
  # When deployed these settings are loaded when job server starts
  #
  # Spark Cluster / Job Server configuration
  # Spark Cluster / Job Server configuration
  spark {
    # spark.master will be passed to each job's JobContext
    master = &lt;spark_master&gt;
  
    # Default # of CPUs for jobs to use for Spark standalone cluster
    job-number-cpus = 4
  
    jobserver {
      port = 8090
  
      context-per-jvm = false
      context-creation-timeout = 100 s
      # Note: JobFileDAO is deprecated from v0.7.0 because of issues in
      # production and will be removed in future, now defaults to H2 file.
      jobdao = spark.jobserver.io.JobSqlDAO
  
      filedao {
        rootdir = /tmp/spark-jobserver/filedao/data
      }
  
      datadao {
        rootdir = /tmp/spark-jobserver/upload
      }
  
      sqldao {
        slick-driver = slick.driver.H2Driver
  
        jdbc-driver = org.h2.Driver
  
        rootdir = /tmp/spark-jobserver/sqldao/data
  
        jdbc {
          url = "jdbc:h2:file:/tmp/spark-jobserver/sqldao/data/h2-db"
          user = ""
          password = ""
        }
  
        dbcp {
          enabled = false
          maxactive = 20
          maxidle = 10
          initialsize = 10
        }
      }
      result-chunk-size = 1m
      short-timeout = 60 s    
    }
  
    context-settings {
      num-cpu-cores = 2           # Number of cores to allocate.  Required.
      memory-per-node = 512m         # Executor memory per node, -Xmx style eg 512m, #1G, etc.
  
    }
  
  }
  
  akka {
    remote.netty.tcp {
      # This controls the maximum message size, including job results, that can be sent
      # maximum-frame-size = 200 MiB
    }
  }
  
  # check the reference.conf in spray-can/src/main/resources for all defined settings
  spray.can.server.parsing.max-content-length = 250m
  </code></pre>
  
  <p>I am using <code>spark-2.0-preview</code> version.</p>