Github user shubhamchopra commented on a diff in the pull request:
https://github.com/apache/spark/pull/14412#discussion_r101854267
--- Diff:
core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala
---
@@ -195,17 +198,39 @@ class BlockManagerMasterEndpoint(
// Remove it from blockManagerInfo and remove all the blocks.
blockManagerInfo.remove(blockManagerId)
+
val iterator = info.blocks.keySet.iterator
while (iterator.hasNext) {
val blockId = iterator.next
val locations = blockLocations.get(blockId)
locations -= blockManagerId
if (locations.size == 0) {
blockLocations.remove(blockId)
+ logWarning(s"No more replicas available for $blockId !")
+ } else if (proactivelyReplicate && (blockId.isRDD ||
blockId.isInstanceOf[TestBlockId])) {
+ // only RDD blocks store data that users explicitly cache so we
only need to proactively
+ // replicate RDD blocks
+ // broadcast related blocks exist on all executors, so we don't
worry about them
+ // we also need to replicate this behavior for test blocks for
unit tests
+ // we send a message to a randomly chosen executor location to
replicate block
+ // assuming single executor failure, we find out how many replicas
existed before failure
+ val maxReplicas = locations.size + 1
+
+ val i = (new Random(blockId.hashCode)).nextInt(locations.size)
+ val blockLocations = locations.toSeq
+ val candidateBMId = blockLocations(i)
+ val blockManager = blockManagerInfo.get(candidateBMId)
+ if(blockManager.isDefined) {
+ val remainingLocations = locations.toSeq.filter(bm => bm !=
candidateBMId)
--- End diff --
If we are at this point, there would be atleast one location with the block
which will get chosen as the candidate here. `remainingLocations` just tells
the replication logic where other replicas are present (if any, so it can be an
empty set), so it can use that info while choosing candidate executors for
replication.
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