Github user tdas commented on a diff in the pull request:
https://github.com/apache/spark/pull/7279#discussion_r36041200
--- Diff:
core/src/test/scala/org/apache/spark/rdd/LocalCheckpointSuite.scala ---
@@ -0,0 +1,330 @@
+/*
+ * 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.rdd
+
+import org.apache.spark.{SparkException, SparkContext, LocalSparkContext,
SparkFunSuite}
+
+import org.mockito.Mockito.spy
+import org.apache.spark.storage.{RDDBlockId, StorageLevel}
+
+/**
+ * Fine-grained tests for local checkpointing.
+ * For end-to-end tests, see CheckpointSuite.
+ */
+class LocalCheckpointSuite extends SparkFunSuite with LocalSparkContext {
+
+ override def beforeEach(): Unit = {
+ sc = new SparkContext("local[2]", "test")
+ }
+
+ test("transform storage level") {
+ val transform = LocalRDDCheckpointData.transformStorageLevel _
+ assert(transform(StorageLevel.NONE) === StorageLevel.DISK_ONLY)
+ assert(transform(StorageLevel.MEMORY_ONLY) ===
StorageLevel.MEMORY_AND_DISK)
+ assert(transform(StorageLevel.MEMORY_ONLY_SER) ===
StorageLevel.MEMORY_AND_DISK_SER)
+ assert(transform(StorageLevel.MEMORY_ONLY_2) ===
StorageLevel.MEMORY_AND_DISK_2)
+ assert(transform(StorageLevel.MEMORY_ONLY_SER_2) ===
StorageLevel.MEMORY_AND_DISK_SER_2)
+ assert(transform(StorageLevel.DISK_ONLY) === StorageLevel.DISK_ONLY)
+ assert(transform(StorageLevel.DISK_ONLY_2) ===
StorageLevel.DISK_ONLY_2)
+ assert(transform(StorageLevel.MEMORY_AND_DISK) ===
StorageLevel.MEMORY_AND_DISK)
+ assert(transform(StorageLevel.MEMORY_AND_DISK_SER) ===
StorageLevel.MEMORY_AND_DISK_SER)
+ assert(transform(StorageLevel.MEMORY_AND_DISK_2) ===
StorageLevel.MEMORY_AND_DISK_2)
+ assert(transform(StorageLevel.MEMORY_AND_DISK_SER_2) ===
StorageLevel.MEMORY_AND_DISK_SER_2)
+ // Off-heap is not supported and Spark should fail fast
+ intercept[SparkException] {
+ transform(StorageLevel.OFF_HEAP)
+ }
+ }
+
+ test("basic lineage truncation") {
+ val numPartitions = 4
+ val parallelRdd = sc.parallelize(1 to 100, numPartitions)
+ val mappedRdd = parallelRdd.map { i => i + 1 }
+ val filteredRdd = mappedRdd.filter { i => i % 2 == 0 }
+ val expectedPartitionIndices = (0 until numPartitions).toArray
+ assert(filteredRdd.checkpointData.isEmpty)
+ assert(filteredRdd.getStorageLevel === StorageLevel.NONE)
+ assert(filteredRdd.partitions.map(_.index) ===
expectedPartitionIndices)
+ assert(filteredRdd.dependencies.size === 1)
+ assert(filteredRdd.dependencies.head.rdd === mappedRdd)
+ assert(mappedRdd.dependencies.size === 1)
+ assert(mappedRdd.dependencies.head.rdd === parallelRdd)
+ assert(parallelRdd.dependencies.size === 0)
+
+ // Mark the RDD for local checkpointing
+ filteredRdd.localCheckpoint()
+ assert(filteredRdd.checkpointData.isDefined)
+ assert(!filteredRdd.checkpointData.get.isCheckpointed)
+ assert(!filteredRdd.checkpointData.get.checkpointRDD.isDefined)
+ assert(filteredRdd.getStorageLevel ===
LocalRDDCheckpointData.DEFAULT_STORAGE_LEVEL)
+
+ // After an action, the lineage is truncated
+ val result = filteredRdd.collect()
+ assert(filteredRdd.checkpointData.get.isCheckpointed)
+ assert(filteredRdd.checkpointData.get.checkpointRDD.isDefined)
+ val checkpointRdd =
filteredRdd.checkpointData.flatMap(_.checkpointRDD).get
+ assert(filteredRdd.dependencies.size === 1)
+ assert(filteredRdd.dependencies.head.rdd === checkpointRdd)
+ assert(filteredRdd.partitions.map(_.index) ===
expectedPartitionIndices)
+ assert(checkpointRdd.partitions.map(_.index) ===
expectedPartitionIndices)
+
+ // Recomputation should yield the same result
+ assert(filteredRdd.collect() === result)
+ assert(filteredRdd.collect() === result)
+ }
+
+ test("basic lineage truncation - caching before checkpointing") {
+ testBasicLineageTruncationWithCaching(
+ newRdd.persist(StorageLevel.MEMORY_ONLY).localCheckpoint(),
+ StorageLevel.MEMORY_AND_DISK)
+ }
+
+ test("basic lineage truncation - caching after checkpointing") {
+ testBasicLineageTruncationWithCaching(
+ newRdd.localCheckpoint().persist(StorageLevel.MEMORY_ONLY),
+ StorageLevel.MEMORY_AND_DISK)
+ }
+
+ test("indirect lineage truncation") {
+ testIndirectLineageTruncation(
+ newRdd.localCheckpoint(),
+ LocalRDDCheckpointData.DEFAULT_STORAGE_LEVEL)
+ }
+
+ test("indirect lineage truncation - caching before checkpointing") {
+ testIndirectLineageTruncation(
+ newRdd.persist(StorageLevel.MEMORY_ONLY).localCheckpoint(),
+ StorageLevel.MEMORY_AND_DISK)
+ }
+
+ test("indirect lineage truncation - caching after checkpointing") {
+ testIndirectLineageTruncation(
+ newRdd.localCheckpoint().persist(StorageLevel.MEMORY_ONLY),
+ StorageLevel.MEMORY_AND_DISK)
+ }
+
+ test("checkpoint without draining iterator") {
+ testWithoutDrainingIterator(
+ newSortedRdd.localCheckpoint(),
+ LocalRDDCheckpointData.DEFAULT_STORAGE_LEVEL,
+ 50)
+ }
+
+ test("checkpoint without draining iterator - caching before
checkpointing") {
+ testWithoutDrainingIterator(
+ newSortedRdd.persist(StorageLevel.MEMORY_ONLY).localCheckpoint(),
+ StorageLevel.MEMORY_AND_DISK,
+ 50)
+ }
+
+ test("checkpoint without draining iterator - caching after
checkpointing") {
+ testWithoutDrainingIterator(
+ newSortedRdd.localCheckpoint().persist(StorageLevel.MEMORY_ONLY),
+ StorageLevel.MEMORY_AND_DISK,
+ 50)
+ }
+
+ test("checkpoint blocks exist") {
+ testCheckpointBlocksExist(
+ newRdd.localCheckpoint(),
+ LocalRDDCheckpointData.DEFAULT_STORAGE_LEVEL)
+ }
+
+ test("checkpoint blocks exist - caching before checkpointing") {
+ testCheckpointBlocksExist(
+ newRdd.persist(StorageLevel.MEMORY_ONLY).localCheckpoint(),
+ StorageLevel.MEMORY_AND_DISK)
+ }
+
+ test("checkpoint blocks exist - caching after checkpointing") {
+ testCheckpointBlocksExist(
+ newRdd.localCheckpoint().persist(StorageLevel.MEMORY_ONLY),
+ StorageLevel.MEMORY_AND_DISK)
+ }
+
+ test("missing checkpoint block fails with informative message") {
+ val rdd = newRdd.localCheckpoint()
+ val numPartitions = rdd.partitions.size
+ val partitionIndices = rdd.partitions.map(_.index)
+ val bmm = sc.env.blockManager.master
+
+ // After an action, the blocks should be found somewhere in the cache
+ rdd.collect()
+ partitionIndices.foreach { i =>
+ assert(bmm.contains(RDDBlockId(rdd.id, i)))
+ }
+
+ // Remove one of the blocks to simulate executor failure
+ // Collecting the RDD should now fail with an informative exception
+ val blockId = RDDBlockId(rdd.id, numPartitions - 1)
+ bmm.removeBlock(blockId)
+ try {
+ rdd.collect()
+ fail("Collect should have failed if local checkpoint block is
removed...")
+ } catch {
+ case se: SparkException =>
+ assert(se.getMessage.contains(s"Checkpoint block $blockId not
found"))
+ assert(se.getMessage.contains("rdd.checkpoint()")) // suggest an
alternative
+ assert(se.getMessage.contains("fault-tolerant")) // justify the
alternative
+ }
+ }
+
+ /**
+ * Helper method to create a simple RDD.
+ */
+ private def newRdd: RDD[Int] = {
+ sc.parallelize(1 to 100, 4)
+ .map { i => i + 1 }
+ .filter { i => i % 2 == 0 }
+ }
+
+ /**
+ * Helper method to create a simple sorted RDD.
+ */
+ private def newSortedRdd: RDD[Int] = newRdd.sortBy(identity)
+
+ /**
+ * Helper method to test basic lineage truncation with caching.
+ *
+ * @param rdd an RDD that is both marked for caching and local
checkpointing
+ */
+ private def testBasicLineageTruncationWithCaching[T](
+ rdd: RDD[T],
+ targetStorageLevel: StorageLevel): Unit = {
+ require(targetStorageLevel !== StorageLevel.NONE)
+ require(rdd.getStorageLevel !== StorageLevel.NONE)
+ require(rdd.isLocallyCheckpointed)
+ val result = rdd.collect()
+ assert(rdd.getStorageLevel === targetStorageLevel)
+ assert(rdd.checkpointData.isDefined)
+ assert(rdd.checkpointData.get.isCheckpointed)
+ assert(rdd.checkpointData.get.checkpointRDD.isDefined)
+ assert(rdd.dependencies.head.rdd ===
rdd.checkpointData.get.checkpointRDD.get)
+ assert(rdd.collect() === result)
+ assert(rdd.collect() === result)
+ }
+
+ /**
+ * Helper method to test indirect lineage truncation.
+ *
+ * Indirect lineage truncation here means the action is called on one of
the
+ * checkpointed RDD's descendants, but not on the checkpointed RDD
itself.
+ *
+ * @param rdd a locally checkpointed RDD
+ */
+ private def testIndirectLineageTruncation[T](
+ rdd: RDD[T],
+ targetStorageLevel: StorageLevel): Unit = {
+ require(targetStorageLevel !== StorageLevel.NONE)
+ require(rdd.isLocallyCheckpointed)
+ val rdd1 = rdd.map { i => i + "1" }
+ val rdd2 = rdd1.map { i => i + "2" }
+ val rdd3 = rdd2.map { i => i + "3" }
+ val rddDependencies = rdd.dependencies
+ val rdd1Dependencies = rdd1.dependencies
+ val rdd2Dependencies = rdd2.dependencies
+ val rdd3Dependencies = rdd3.dependencies
+ assert(rdd1Dependencies.size === 1)
+ assert(rdd1Dependencies.head.rdd === rdd)
+ assert(rdd2Dependencies.size === 1)
+ assert(rdd2Dependencies.head.rdd === rdd1)
+ assert(rdd3Dependencies.size === 1)
+ assert(rdd3Dependencies.head.rdd === rdd2)
+
+ // Only the locally checkpointed RDD should have special storage level
+ assert(rdd.getStorageLevel === targetStorageLevel)
+ assert(rdd1.getStorageLevel === StorageLevel.NONE)
+ assert(rdd2.getStorageLevel === StorageLevel.NONE)
+ assert(rdd3.getStorageLevel === StorageLevel.NONE)
+
+ // After an action, only the dependencies of the checkpointed RDD
changes
+ val result = rdd3.collect()
+ assert(rdd.dependencies !== rddDependencies)
+ assert(rdd1.dependencies === rdd1Dependencies)
+ assert(rdd2.dependencies === rdd2Dependencies)
+ assert(rdd3.dependencies === rdd3Dependencies)
+ assert(rdd3.collect() === result)
+ assert(rdd3.collect() === result)
+ }
+
+ /**
+ * Helper method to test checkpointing without fully draining the
iterator.
+ *
+ * Not all RDD actions fully consume the iterator. As a result, a subset
of the partitions
+ * may not be cached. However, since we want to truncate the lineage
safely, we explicitly
+ * ensure that *all* partitions are fully cached. This method asserts
this behavior.
+ *
+ * @param rdd a locally checkpointed RDD
+ */
+ private def testWithoutDrainingIterator[T](
+ rdd: RDD[T],
+ targetStorageLevel: StorageLevel,
+ targetCount: Int): Unit = {
+ require(targetCount > 0)
+ require(targetStorageLevel !== StorageLevel.NONE)
+ require(rdd.isLocallyCheckpointed)
+
+ // This does not drain the iterator, but checkpointing should still
work
+ val first = rdd.first()
+ assert(rdd.count() === targetCount)
+ assert(rdd.count() === targetCount)
+ assert(rdd.first() === first)
+ assert(rdd.first() === first)
+
+ // Test the same thing by calling actions on a descendant instead
+ val rdd1 = rdd.repartition(10)
--- End diff --
Nit: Why would this ever fail if the `rdd.collect()` gives same result
before and after checkpointing has occurred? If above you simply test whether
rdd.collect() is sufficient, then these further tests seems superfluous.
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