Github user vanzin commented on a diff in the pull request:
https://github.com/apache/spark/pull/1195#discussion_r14309466
--- Diff:
streaming/src/main/scala/org/apache/spark/streaming/receiver/BlockGenerator.scala
---
@@ -134,9 +168,26 @@ private[streaming] class BlockGenerator(
logError(message, t)
listener.onError(message, t)
}
-
+
private def pushBlock(block: Block) {
listener.onPushBlock(block.id, block.buffer)
+
+ var callbackBufferOpt: Option[ArrayBuffer[Callback]] = None
+ // Remove the buffer from the callbacks map. This must be synchronized
to ensure no one else
+ // is editing the buffer or the map at that time.
+ synchronized {
+ callbackBufferOpt = Option(callbacks.remove(block.id))
+ }
+
+ // Call the callbacks
+ callbackBufferOpt match {
+ case Some(callbackBuffer) =>
+ callbackBuffer.map(callback => {
--- End diff --
AFAIK `foreach` doesn't need to collect the results of the closure into a
new object, so you save a little in memory allocation. (For an Option that
means not having to allocate a new Option, for a list it means not needing a
completely new list with the transformed objects.)
Or, in other words: `map()` returns a `Seq[T]`, `foreach()` returns `Unit`.
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