Github user tdas commented on a diff in the pull request:
https://github.com/apache/spark/pull/9421#discussion_r44083518
--- Diff:
extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisCheckpointer.scala
---
@@ -0,0 +1,117 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.streaming.kinesis
+
+import java.util.concurrent._
+
+import scala.util.control.NonFatal
+
+import
com.amazonaws.services.kinesis.clientlibrary.interfaces.IRecordProcessorCheckpointer
+import com.amazonaws.services.kinesis.clientlibrary.types.ShutdownReason
+
+import org.apache.spark.Logging
+import org.apache.spark.streaming.Duration
+import org.apache.spark.util.ThreadUtils
+
+/**
+ * This is a helper class for managing Kinesis checkpointing.
+ *
+ * @param receiver The receiver that keeps track of which sequence numbers
we can checkpoint
+ * @param checkpointInterval How frequently we will checkpoint to DynamoDB
+ * @param workerId Worker Id of KCL worker for logging purposes
+ */
+private[kinesis] class KinesisCheckpointer(
+ receiver: KinesisReceiver[_],
+ checkpointInterval: Duration,
+ workerId: String) extends Logging {
+
+ // a map from shardId's to checkpointers
+ private val checkpointers = new ConcurrentHashMap[String,
IRecordProcessorCheckpointer]()
+
+ private val lastCheckpointedSeqNums = new ConcurrentHashMap[String,
String]()
+
+ private val checkpointerThread = startCheckpointerThread()
+
+ /** Update the checkpointer instance to the most recent one for the
given shardId. */
+ def setCheckpointer(shardId: String, checkpointer:
IRecordProcessorCheckpointer): Unit = {
+ checkpointers.put(shardId, checkpointer)
+ }
+
+ /**
+ * Stop tracking the specified shardId.
+ *
+ * If a checkpointer is provided, e.g. on IRecordProcessor.shutdown
[[ShutdownReason.TERMINATE]],
+ * we will use that to make the final checkpoint. If `null` is provided,
we will not make the
+ * checkpoint, e.g. in case of [[ShutdownReason.ZOMBIE]].
+ */
+ def removeCheckpointer(shardId: String, checkpointer:
IRecordProcessorCheckpointer): Unit = {
+ checkpoint(shardId, Option(checkpointer))
+ checkpointers.remove(shardId)
+ }
+
+ /** Perform the checkpoint. Exposed for tests. */
+ private[kinesis] def checkpoint(
+ shardId: String,
+ checkpointer: Option[IRecordProcessorCheckpointer]): Unit = {
+ // if this method throws an exception, then the scheduled task will
not run again
+ try {
+ checkpointer.foreach { cp =>
+ receiver.getLatestSeqNumToCheckpoint(shardId).foreach {
latestSeqNum =>
+ val lastSeqNum = lastCheckpointedSeqNums.get(shardId)
+ // Kinesis sequence numbers are monotonically increasing
strings, therefore we can do
+ // safely do the string comparison
+ if (lastSeqNum == null || latestSeqNum > lastSeqNum) {
+ /* Perform the checkpoint */
+
KinesisRecordProcessor.retryRandom(cp.checkpoint(latestSeqNum), 4, 100)
+ logDebug(s"Checkpoint: WorkerId $workerId completed
checkpoint at sequence number" +
+ s" $latestSeqNum for shardId $shardId")
+ lastCheckpointedSeqNums.put(shardId, latestSeqNum)
+ }
+ }
+ }
+ } catch {
+ case NonFatal(e) =>
+ logError("Failed to checkpoint to DynamoDB.", e)
+ }
+ }
+
+ /**
+ * Start the checkpointer thread with the given checkpoint duration.
Exposed for tests.
+ */
+ private[kinesis] def startCheckpointerThread(): ScheduledFuture[_] = {
+ val period = checkpointInterval.milliseconds
+ val ex =
+ ThreadUtils.newDaemonSingleThreadScheduledExecutor(s"Kinesis
Checkpointer - Worker $workerId")
+ val task = new Runnable {
+ def run() = {
+ val shardIds = checkpointers.keys()
+ while (shardIds.hasMoreElements) {
+ val shardId = shardIds.nextElement()
+ checkpoint(shardId, Option(checkpointers.get(shardId)))
+ }
+ }
+ }
+ ex.scheduleAtFixedRate(task, period, period, TimeUnit.MILLISECONDS)
+ }
+
+ /**
+ * Shutdown the checkpointer. Should be called on the onStop of the
Receiver.
+ */
+ def shutdown(): Unit = {
--- End diff --
Dont you want to checkpoint one final time?
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