Github user JoshRosen commented on a diff in the pull request:
https://github.com/apache/spark/pull/14412#discussion_r101447632
--- 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)
--- End diff --
Why do we need to use a fixed random seed here? Testing?
Also, isn't there a `Random.choice()` that you can use for this? Or a
method like that in our own `Utils` class?
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