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From rxin <...@git.apache.org>
Subject [GitHub] spark pull request: [SPARK-3495] Block replication fails continuou...
Date Mon, 22 Sep 2014 01:20:41 GMT
Github user rxin commented on a diff in the pull request:

    https://github.com/apache/spark/pull/2366#discussion_r17829956
  
    --- Diff: core/src/main/scala/org/apache/spark/storage/BlockManager.scala ---
    @@ -787,31 +789,88 @@ private[spark] class BlockManager(
       }
     
       /**
    +   * Get peer block managers in the system.
    +   */
    +  private def getPeers(forceFetch: Boolean): HashSet[BlockManagerId] = {
    +    val cachedPeersTtl = conf.getInt("spark.storage.cachedPeersTtl", 60 * 1000) // milliseconds
    +    val timeout = System.currentTimeMillis - lastPeerFetchTime > cachedPeersTtl
    +
    +    cachedPeers.synchronized {
    +      if (cachedPeers.isEmpty || forceFetch || timeout) {
    +        cachedPeers.clear()
    +        cachedPeers ++= master.getPeers(blockManagerId).sortBy(_.hashCode)
    +        lastPeerFetchTime = System.currentTimeMillis
    +        logDebug("Fetched peers from master: " + cachedPeers.mkString("[", ",", "]"))
    +      }
    +    }
    +    cachedPeers
    +  }
    +
    +  /**
        * Replicate block to another node.
        */
    -  @volatile var cachedPeers: Seq[BlockManagerId] = null
       private def replicate(blockId: BlockId, data: ByteBuffer, level: StorageLevel): Unit
= {
    +    val maxReplicationFailures = conf.getInt("spark.storage.maxReplicationFailures",
1)
    +    val numPeersToReplicateTo = level.replication - 1
    +    val peersReplicatedTo = new HashSet[BlockManagerId]
    +    val peersFailedToReplicateTo = new HashSet[BlockManagerId]
         val tLevel = StorageLevel(
           level.useDisk, level.useMemory, level.useOffHeap, level.deserialized, 1)
    -    if (cachedPeers == null) {
    -      cachedPeers = master.getPeers(blockManagerId, level.replication - 1)
    +    val startTime = System.nanoTime
    +    val random = new Random(blockId.hashCode)
    +
    +    var forceFetchPeers = false
    +    var failures = 0
    +    var done = false
    +
    +    // Get a random peer
    +    def getRandomPeer(): Option[BlockManagerId] = {
    +      val peers = getPeers(forceFetchPeers) -- peersReplicatedTo -- peersFailedToReplicateTo
    +      if (!peers.isEmpty) Some(peers.toSeq(random.nextInt(peers.size))) else None
    --- End diff --
    
    the toSeq seems expensive?


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