Spark Jobserver - stress test - Async POST error response: akka.pattern.AskTimeoutException - apache-spark

Question

Hi I am trying to do stress test on the spark job server, and I am sharing the spark context with the following properties among the submitted jobs.
spark.executor.cores='2'
spark.cores.max='1'
spark.driver.cores='1'
spark.driver.memory='1g'
spark.executor.memory='1g'
spark.executor.instances='2'
spark.scheduler.mode='FAIR'
spark.scheduler.pool='fair_pool'
spark.scheduler.allocation.file='/spark-jobserver/scheduler.xml
When I post 10 jobs in 100 ms using Jmeter, only 4 to 5 jobs gives success respons and others give the following error:
{
"status": "ERROR",
"result": {
"message": "Ask timed out on [Actor[akka://JobServer/user/context-supervisor/admin-context#-1409264293]] 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:748)"]
}
}
Please note that I am expecting asynchronous success response for how much ever the reponse time can be.