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https://issues.apache.org/jira/browse/SPARK-2243?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15103298#comment-15103298
 ] 

Sean Owen commented on SPARK-2243:
----------------------------------

Yes, dynamic allocation operates in units of executors. You can make these 
smallish, but they are inevitably fairly coarse units.

You can have multiple contexts; they just have to occupy their own JVMs. I 
think this is what much of the discussion comes down to. The intended usage is 
to manage resources via a cluster resource managers and spark-submit 
applications to that cluster. Multiple contexts in one JVM is miniature 
duplicate of this system and just not really the intended usage.

A long-running context to avoid the overhead of starting a context is an 
orthogonal issue. This by itself is unrelated to whether several of those 
contexts should be in one JVM.

I misspoke above; multiple contexts in one JVM doesn't let you share RDDs. It 
might let you share some singletons and static state. This makes it less 
interesting IMHO. Sharing RDDs isn't enabled by having multiple contexts in one 
JVM.

Yes, on the positive side, separating contexts for logically separate 
applications gives you isolation, which is probably a good thing.

> Support multiple SparkContexts in the same JVM
> ----------------------------------------------
>
>                 Key: SPARK-2243
>                 URL: https://issues.apache.org/jira/browse/SPARK-2243
>             Project: Spark
>          Issue Type: New Feature
>          Components: Block Manager, Spark Core
>    Affects Versions: 0.7.0, 1.0.0, 1.1.0
>            Reporter: Miguel Angel Fernandez Diaz
>
> We're developing a platform where we create several Spark contexts for 
> carrying out different calculations. Is there any restriction when using 
> several Spark contexts? We have two contexts, one for Spark calculations and 
> another one for Spark Streaming jobs. The next error arises when we first 
> execute a Spark calculation and, once the execution is finished, a Spark 
> Streaming job is launched:
> {code}
> 14/06/23 16:40:08 ERROR executor.Executor: Exception in task ID 0
> java.io.FileNotFoundException: http://172.19.0.215:47530/broadcast_0
>       at 
> sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1624)
>       at 
> org.apache.spark.broadcast.HttpBroadcast$.read(HttpBroadcast.scala:156)
>       at 
> org.apache.spark.broadcast.HttpBroadcast.readObject(HttpBroadcast.scala:56)
>       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>       at 
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>       at 
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>       at java.lang.reflect.Method.invoke(Method.java:606)
>       at 
> java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
>       at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1893)
>       at 
> java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
>       at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
>       at 
> java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
>       at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
>       at 
> java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
>       at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
>       at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
>       at 
> org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:40)
>       at 
> org.apache.spark.scheduler.ResultTask$.deserializeInfo(ResultTask.scala:63)
>       at 
> org.apache.spark.scheduler.ResultTask.readExternal(ResultTask.scala:139)
>       at 
> java.io.ObjectInputStream.readExternalData(ObjectInputStream.java:1837)
>       at 
> java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1796)
>       at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
>       at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
>       at 
> org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:40)
>       at 
> org.apache.spark.serializer.JavaSerializerInstance.deserialize(JavaSerializer.scala:62)
>       at 
> org.apache.spark.executor.Executor$TaskRunner$$anonfun$run$1.apply$mcV$sp(Executor.scala:193)
>       at 
> org.apache.spark.deploy.SparkHadoopUtil.runAsUser(SparkHadoopUtil.scala:45)
>       at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:176)
>       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)
> 14/06/23 16:40:08 WARN scheduler.TaskSetManager: Lost TID 0 (task 0.0:0)
> 14/06/23 16:40:08 WARN scheduler.TaskSetManager: Loss was due to 
> java.io.FileNotFoundException
> java.io.FileNotFoundException: http://172.19.0.215:47530/broadcast_0
>       at 
> sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1624)
>       at 
> org.apache.spark.broadcast.HttpBroadcast$.read(HttpBroadcast.scala:156)
>       at 
> org.apache.spark.broadcast.HttpBroadcast.readObject(HttpBroadcast.scala:56)
>       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>       at 
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>       at 
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>       at java.lang.reflect.Method.invoke(Method.java:606)
>       at 
> java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
>       at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1893)
>       at 
> java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
>       at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
>       at 
> java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
>       at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
>       at 
> java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
>       at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
>       at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
>       at 
> org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:40)
>       at 
> org.apache.spark.scheduler.ResultTask$.deserializeInfo(ResultTask.scala:63)
>       at 
> org.apache.spark.scheduler.ResultTask.readExternal(ResultTask.scala:139)
>       at 
> java.io.ObjectInputStream.readExternalData(ObjectInputStream.java:1837)
>       at 
> java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1796)
>       at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
>       at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
>       at 
> org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:40)
>       at 
> org.apache.spark.serializer.JavaSerializerInstance.deserialize(JavaSerializer.scala:62)
>       at 
> org.apache.spark.executor.Executor$TaskRunner$$anonfun$run$1.apply$mcV$sp(Executor.scala:193)
>       at 
> org.apache.spark.deploy.SparkHadoopUtil.runAsUser(SparkHadoopUtil.scala:45)
>       at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:176)
>       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)
> 14/06/23 16:40:08 ERROR scheduler.TaskSetManager: Task 0.0:0 failed 1 times; 
> aborting job
> 14/06/23 16:40:08 INFO scheduler.TaskSchedulerImpl: Removed TaskSet 0.0, 
> whose tasks have all completed, from pool 
> 14/06/23 16:40:08 INFO scheduler.DAGScheduler: Failed to run runJob at 
> NetworkInputTracker.scala:182
> [WARNING] 
> org.apache.spark.SparkException: Job aborted: Task 0.0:0 failed 1 times (most 
> recent failure: Exception failure: java.io.FileNotFoundException: 
> http://172.19.0.215:47530/broadcast_0)
>       at 
> org.apache.spark.scheduler.DAGScheduler$$anonfun$org$apache$spark$scheduler$DAGScheduler$$abortStage$1.apply(DAGScheduler.scala:1020)
>       at 
> org.apache.spark.scheduler.DAGScheduler$$anonfun$org$apache$spark$scheduler$DAGScheduler$$abortStage$1.apply(DAGScheduler.scala:1018)
>       at 
> scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
>       at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
>       at 
> org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$abortStage(DAGScheduler.scala:1018)
>       at 
> org.apache.spark.scheduler.DAGScheduler$$anonfun$processEvent$10.apply(DAGScheduler.scala:604)
>       at 
> org.apache.spark.scheduler.DAGScheduler$$anonfun$processEvent$10.apply(DAGScheduler.scala:604)
>       at scala.Option.foreach(Option.scala:236)
>       at 
> org.apache.spark.scheduler.DAGScheduler.processEvent(DAGScheduler.scala:604)
>       at 
> org.apache.spark.scheduler.DAGScheduler$$anonfun$start$1$$anon$2$$anonfun$receive$1.applyOrElse(DAGScheduler.scala:190)
>       at akka.actor.ActorCell.receiveMessage(ActorCell.scala:498)
>       at akka.actor.ActorCell.invoke(ActorCell.scala:456)
>       at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:237)
>       at akka.dispatch.Mailbox.run(Mailbox.scala:219)
>       at 
> akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:385)
>       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)
> 14/06/23 16:40:09 INFO dstream.ForEachDStream: metadataCleanupDelay = 3600
> {code}
> So far, we are working on localhost. Any clue about where this error is 
> coming from? Any workaround to solve the issue?



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