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Posted to commits@spark.apache.org by yh...@apache.org on 2016/11/29 23:01:16 UTC
spark git commit: [SPARK-18631][SQL] Changed ExchangeCoordinator
re-partitioning to avoid more data skew
Repository: spark
Updated Branches:
refs/heads/master d57a594b8 -> f8878a4c6
[SPARK-18631][SQL] Changed ExchangeCoordinator re-partitioning to avoid more data skew
## What changes were proposed in this pull request?
Re-partitioning logic in ExchangeCoordinator changed so that adding another pre-shuffle partition to the post-shuffle partition will not be done if doing so would cause the size of the post-shuffle partition to exceed the target partition size.
## How was this patch tested?
Existing tests updated to reflect new expectations.
Author: Mark Hamstra <ma...@gmail.com>
Closes #16065 from markhamstra/SPARK-17064.
Project: http://git-wip-us.apache.org/repos/asf/spark/repo
Commit: http://git-wip-us.apache.org/repos/asf/spark/commit/f8878a4c
Tree: http://git-wip-us.apache.org/repos/asf/spark/tree/f8878a4c
Diff: http://git-wip-us.apache.org/repos/asf/spark/diff/f8878a4c
Branch: refs/heads/master
Commit: f8878a4c6f7c4ebb16e4aef26ad0869ba12eb9fc
Parents: d57a594
Author: Mark Hamstra <ma...@gmail.com>
Authored: Tue Nov 29 15:01:12 2016 -0800
Committer: Yin Huai <yh...@databricks.com>
Committed: Tue Nov 29 15:01:12 2016 -0800
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.../exchange/ExchangeCoordinator.scala | 32 ++++++++--------
.../execution/ExchangeCoordinatorSuite.scala | 40 ++++++++++----------
2 files changed, 35 insertions(+), 37 deletions(-)
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http://git-wip-us.apache.org/repos/asf/spark/blob/f8878a4c/sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/ExchangeCoordinator.scala
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diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/ExchangeCoordinator.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/ExchangeCoordinator.scala
index 57da85f..deb2c24 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/ExchangeCoordinator.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/ExchangeCoordinator.scala
@@ -69,15 +69,18 @@ import org.apache.spark.sql.execution.{ShuffledRowRDD, SparkPlan}
* post-shuffle partition. Once we have size statistics of pre-shuffle partitions from stages
* corresponding to the registered [[ShuffleExchange]]s, we will do a pass of those statistics and
* pack pre-shuffle partitions with continuous indices to a single post-shuffle partition until
- * the size of a post-shuffle partition is equal or greater than the target size.
+ * adding another pre-shuffle partition would cause the size of a post-shuffle partition to be
+ * greater than the target size.
+ *
* For example, we have two stages with the following pre-shuffle partition size statistics:
* stage 1: [100 MB, 20 MB, 100 MB, 10MB, 30 MB]
* stage 2: [10 MB, 10 MB, 70 MB, 5 MB, 5 MB]
* assuming the target input size is 128 MB, we will have three post-shuffle partitions,
* which are:
- * - post-shuffle partition 0: pre-shuffle partition 0 and 1
- * - post-shuffle partition 1: pre-shuffle partition 2
- * - post-shuffle partition 2: pre-shuffle partition 3 and 4
+ * - post-shuffle partition 0: pre-shuffle partition 0 (size 110 MB)
+ * - post-shuffle partition 1: pre-shuffle partition 1 (size 30 MB)
+ * - post-shuffle partition 2: pre-shuffle partition 2 (size 170 MB)
+ * - post-shuffle partition 3: pre-shuffle partition 3 and 4 (size 50 MB)
*/
class ExchangeCoordinator(
numExchanges: Int,
@@ -164,25 +167,20 @@ class ExchangeCoordinator(
while (i < numPreShufflePartitions) {
// We calculate the total size of ith pre-shuffle partitions from all pre-shuffle stages.
// Then, we add the total size to postShuffleInputSize.
+ var nextShuffleInputSize = 0L
var j = 0
while (j < mapOutputStatistics.length) {
- postShuffleInputSize += mapOutputStatistics(j).bytesByPartitionId(i)
+ nextShuffleInputSize += mapOutputStatistics(j).bytesByPartitionId(i)
j += 1
}
- // If the current postShuffleInputSize is equal or greater than the
- // targetPostShuffleInputSize, We need to add a new element in partitionStartIndices.
- if (postShuffleInputSize >= targetPostShuffleInputSize) {
- if (i < numPreShufflePartitions - 1) {
- // Next start index.
- partitionStartIndices += i + 1
- } else {
- // This is the last element. So, we do not need to append the next start index to
- // partitionStartIndices.
- }
+ // If including the nextShuffleInputSize would exceed the target partition size, then start a
+ // new partition.
+ if (i > 0 && postShuffleInputSize + nextShuffleInputSize > targetPostShuffleInputSize) {
+ partitionStartIndices += i
// reset postShuffleInputSize.
- postShuffleInputSize = 0L
- }
+ postShuffleInputSize = nextShuffleInputSize
+ } else postShuffleInputSize += nextShuffleInputSize
i += 1
}
http://git-wip-us.apache.org/repos/asf/spark/blob/f8878a4c/sql/core/src/test/scala/org/apache/spark/sql/execution/ExchangeCoordinatorSuite.scala
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diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/ExchangeCoordinatorSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/ExchangeCoordinatorSuite.scala
index 2803b62..06bce9a 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/ExchangeCoordinatorSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/ExchangeCoordinatorSuite.scala
@@ -85,7 +85,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
{
// There are a few large pre-shuffle partitions.
val bytesByPartitionId = Array[Long](110, 10, 100, 110, 0)
- val expectedPartitionStartIndices = Array[Int](0, 1, 3, 4)
+ val expectedPartitionStartIndices = Array[Int](0, 1, 2, 3, 4)
checkEstimation(coordinator, Array(bytesByPartitionId), expectedPartitionStartIndices)
}
@@ -146,7 +146,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
// 2 post-shuffle partition are needed.
val bytesByPartitionId1 = Array[Long](0, 10, 0, 20, 0)
val bytesByPartitionId2 = Array[Long](30, 0, 70, 0, 30)
- val expectedPartitionStartIndices = Array[Int](0, 3)
+ val expectedPartitionStartIndices = Array[Int](0, 2, 4)
checkEstimation(
coordinator,
Array(bytesByPartitionId1, bytesByPartitionId2),
@@ -154,10 +154,10 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
}
{
- // 2 post-shuffle partition are needed.
+ // 4 post-shuffle partition are needed.
val bytesByPartitionId1 = Array[Long](0, 99, 0, 20, 0)
val bytesByPartitionId2 = Array[Long](30, 0, 70, 0, 30)
- val expectedPartitionStartIndices = Array[Int](0, 2)
+ val expectedPartitionStartIndices = Array[Int](0, 1, 2, 4)
checkEstimation(
coordinator,
Array(bytesByPartitionId1, bytesByPartitionId2),
@@ -168,7 +168,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
// 2 post-shuffle partition are needed.
val bytesByPartitionId1 = Array[Long](0, 100, 0, 30, 0)
val bytesByPartitionId2 = Array[Long](30, 0, 70, 0, 30)
- val expectedPartitionStartIndices = Array[Int](0, 2, 4)
+ val expectedPartitionStartIndices = Array[Int](0, 1, 2, 4)
checkEstimation(
coordinator,
Array(bytesByPartitionId1, bytesByPartitionId2),
@@ -179,7 +179,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
// There are a few large pre-shuffle partitions.
val bytesByPartitionId1 = Array[Long](0, 100, 40, 30, 0)
val bytesByPartitionId2 = Array[Long](30, 0, 60, 0, 110)
- val expectedPartitionStartIndices = Array[Int](0, 2, 3)
+ val expectedPartitionStartIndices = Array[Int](0, 1, 2, 3, 4)
checkEstimation(
coordinator,
Array(bytesByPartitionId1, bytesByPartitionId2),
@@ -228,7 +228,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
// The number of post-shuffle partitions is determined by the coordinator.
val bytesByPartitionId1 = Array[Long](10, 50, 20, 80, 20)
val bytesByPartitionId2 = Array[Long](40, 10, 0, 10, 30)
- val expectedPartitionStartIndices = Array[Int](0, 2, 4)
+ val expectedPartitionStartIndices = Array[Int](0, 1, 3, 4)
checkEstimation(
coordinator,
Array(bytesByPartitionId1, bytesByPartitionId2),
@@ -272,13 +272,13 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
sparkConf.set(SQLConf.SHUFFLE_MIN_NUM_POSTSHUFFLE_PARTITIONS.key, "-1")
}
- val spark = SparkSession.builder
+ val spark = SparkSession.builder()
.config(sparkConf)
.getOrCreate()
try f(spark) finally spark.stop()
}
- Seq(Some(3), None).foreach { minNumPostShufflePartitions =>
+ Seq(Some(5), None).foreach { minNumPostShufflePartitions =>
val testNameNote = minNumPostShufflePartitions match {
case Some(numPartitions) => "(minNumPostShufflePartitions: 3)"
case None => ""
@@ -290,7 +290,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
spark
.range(0, 1000, 1, numInputPartitions)
.selectExpr("id % 20 as key", "id as value")
- val agg = df.groupBy("key").count
+ val agg = df.groupBy("key").count()
// Check the answer first.
checkAnswer(
@@ -308,7 +308,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
exchanges.foreach {
case e: ShuffleExchange =>
assert(e.coordinator.isDefined)
- assert(e.outputPartitioning.numPartitions === 3)
+ assert(e.outputPartitioning.numPartitions === 5)
case o =>
}
@@ -316,7 +316,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
exchanges.foreach {
case e: ShuffleExchange =>
assert(e.coordinator.isDefined)
- assert(e.outputPartitioning.numPartitions === 2)
+ assert(e.outputPartitioning.numPartitions === 3)
case o =>
}
}
@@ -359,7 +359,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
exchanges.foreach {
case e: ShuffleExchange =>
assert(e.coordinator.isDefined)
- assert(e.outputPartitioning.numPartitions === 3)
+ assert(e.outputPartitioning.numPartitions === 5)
case o =>
}
@@ -383,14 +383,14 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
.range(0, 1000, 1, numInputPartitions)
.selectExpr("id % 500 as key1", "id as value1")
.groupBy("key1")
- .count
+ .count()
.toDF("key1", "cnt1")
val df2 =
spark
.range(0, 1000, 1, numInputPartitions)
.selectExpr("id % 500 as key2", "id as value2")
.groupBy("key2")
- .count
+ .count()
.toDF("key2", "cnt2")
val join = df1.join(df2, col("key1") === col("key2")).select(col("key1"), col("cnt2"))
@@ -415,13 +415,13 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
exchanges.foreach {
case e: ShuffleExchange =>
assert(e.coordinator.isDefined)
- assert(e.outputPartitioning.numPartitions === 3)
+ assert(e.outputPartitioning.numPartitions === 5)
case o =>
}
case None =>
assert(exchanges.forall(_.coordinator.isDefined))
- assert(exchanges.map(_.outputPartitioning.numPartitions).toSeq.toSet === Set(1, 2))
+ assert(exchanges.map(_.outputPartitioning.numPartitions).toSet === Set(2, 3))
}
}
@@ -435,7 +435,7 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
.range(0, 1000, 1, numInputPartitions)
.selectExpr("id % 500 as key1", "id as value1")
.groupBy("key1")
- .count
+ .count()
.toDF("key1", "cnt1")
val df2 =
spark
@@ -467,13 +467,13 @@ class ExchangeCoordinatorSuite extends SparkFunSuite with BeforeAndAfterAll {
exchanges.foreach {
case e: ShuffleExchange =>
assert(e.coordinator.isDefined)
- assert(e.outputPartitioning.numPartitions === 3)
+ assert(e.outputPartitioning.numPartitions === 5)
case o =>
}
case None =>
assert(exchanges.forall(_.coordinator.isDefined))
- assert(exchanges.map(_.outputPartitioning.numPartitions).toSeq.toSet === Set(2, 3))
+ assert(exchanges.map(_.outputPartitioning.numPartitions).toSet === Set(5, 3))
}
}
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