Github user tdas commented on a diff in the pull request:
https://github.com/apache/spark/pull/9143#discussion_r43337200
--- Diff:
streaming/src/main/scala/org/apache/spark/streaming/scheduler/ReceivedBlockTracker.scala
---
@@ -235,8 +297,84 @@ private[streaming] class ReceivedBlockTracker(
}
}
+ /**
+ * Creates a WAL Writer in a separate thread to enable batching of log
events.
+ * Exposed for tests.
+ */
+ protected def createBatchWriteAheadLogWriter(): Option[BatchLogWriter] =
{
+ if (!WriteAheadLogUtils.isBatchingEnabled(conf)) return None
+ val writer = checkpointDirOption.map(_ => new BatchLogWriter)
+ writer.foreach { runnable =>
+ val thread = new Thread(runnable, "Batch WAL Writer")
+ thread.setDaemon(true)
+ thread.start()
+ }
+ writer
+ }
+
/** Check if the write ahead log is enabled. This is only used for
testing purposes. */
private[streaming] def isWriteAheadLogEnabled: Boolean =
writeAheadLogOption.nonEmpty
+
+ /** A helper class that writes LogEvents in a separate thread to allow
for batching. */
+ private[streaming] class BatchLogWriter extends Runnable {
+
+ var active: Boolean = true
+
+ private def writeRecords(records: Seq[ReceivedBlockTrackerLogEvent]):
Unit = {
+ writeAheadLogOption.foreach { logManager =>
+ if (records.nonEmpty) {
+ logDebug(s"Batched ${records.length} records for WAL write")
+ logManager.write(ByteBuffer.wrap(Utils.serialize(
+ CombinedReceivedBlockTrackerLogEvent(records))),
clock.getTimeMillis())
+ }
+ }
+ }
+
+ def stop(): Unit = {
+ logInfo("Stopping Batch Write Ahead Log writer.")
+ active = false
+ }
+
+ private def flushRecords(): Unit = {
+ val buffer = new ArrayBuffer[ReceivedBlockTrackerLogEvent]()
+ try {
+ buffer.append(walWriteQueue.take())
+ val numBatched = walWriteQueue.drainTo(buffer.asJava) + 1
+ logDebug(s"Received $numBatched records from queue")
+ } catch {
+ case _: InterruptedException =>
+ logWarning("Batch Write Ahead Log Writer queue interrupted.")
+ }
+ def updateRecordStatus(record: ReceivedBlockTrackerLogEvent,
successful: Boolean): Unit = {
--- End diff --
missing new line.
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