[GitHub] flink pull request: [FLINK-1442] Reduce memory consumption of arch...

[tillrohrmann <gi...@git.apache.org>]

Github user tillrohrmann commented on a diff in the pull request:

    https://github.com/apache/flink/pull/344#discussion_r24072128
  
    --- Diff: flink-runtime/src/main/scala/org/apache/flink/runtime/jobmanager/MemoryArchivist.scala ---
    @@ -25,48 +25,82 @@ import org.apache.flink.runtime.jobgraph.JobID
     import org.apache.flink.runtime.messages.ArchiveMessages._
     import org.apache.flink.runtime.messages.JobManagerMessages._
     
    +import scala.collection.mutable.LinkedHashMap
    +import scala.ref.SoftReference
    +
     class MemoryArchivist(private val max_entries: Int) extends Actor with ActorLogMessages with
     ActorLogging {
       /**
        * Map of execution graphs belonging to recently started jobs with the time stamp of the last
    -   * received job event.
    +   * received job event. The insert order is preserved through a LinkedHashMap.
        */
    -  val graphs = collection.mutable.HashMap[JobID, ExecutionGraph]()
    -  val lru = collection.mutable.Queue[JobID]()
    +  val graphs = LinkedHashMap[JobID, SoftReference[ExecutionGraph]]()
     
       override def receiveWithLogMessages: Receive = {
    +    /* Receive Execution Graph to archive */
         case ArchiveExecutionGraph(jobID, graph) => {
    -      graphs.update(jobID, graph)
    +      // wrap graph inside a soft reference
    +      graphs.update(jobID, new SoftReference(graph))
    +
    +      // clear all execution edges of the graph
    +      val iter = graph.getAllExecutionVertices().iterator()
    +      while (iter.hasNext) {
    +        iter.next().clearExecutionEdges()
    +      }
    +
           cleanup(jobID)
         }
     
         case RequestArchivedJobs => {
    -      sender ! ArchivedJobs(graphs.values)
    +      sender ! ArchivedJobs(getAllGraphs())
         }
     
         case RequestJob(jobID) => {
    -      graphs.get(jobID) match {
    -        case Some(graph) => sender ! JobFound(jobID, graph)
    -        case None => sender ! JobNotFound(jobID)
    +      getGraph(jobID) match {
    +        case graph: ExecutionGraph => sender ! JobFound(jobID, graph)
    +        case _ => sender ! JobNotFound(jobID)
           }
         }
     
         case RequestJobStatus(jobID) => {
    -      graphs.get(jobID) match {
    -        case Some(eg) => sender ! CurrentJobStatus(jobID, eg.getState)
    -        case None => sender ! JobNotFound(jobID)
    +      getGraph(jobID) match {
    +        case graph: ExecutionGraph => sender ! CurrentJobStatus(jobID, graph.getState)
    +        case _ => sender ! JobNotFound(jobID)
           }
         }
       }
     
    -  def cleanup(jobID: JobID): Unit = {
    -    if (!lru.contains(jobID)) {
    -      lru.enqueue(jobID)
    +  /**
    +   * Gets all graphs that have not been garbage collected.
    +   * @return An iterable with all valid ExecutionGraphs
    +   */
    +  def getAllGraphs() = graphs.values.flatMap(ref => ref.get match {
    +    case Some(graph) => Seq(graph)
    +    case _ => Seq()
    +  })
    +
    +  /**
    +   * Gets a graph with a jobID if it has not been garbage collected.
    +   * @param jobID
    +   * @return ExecutionGraph or null
    +   */
    +  def getGraph(jobID: JobID) = graphs.get(jobID) match {
    --- End diff --
    
    Why are we doing that? Why not working on the Option type? I don't like null.


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