Repository: spark
Updated Branches:
refs/heads/master 3b5eb7083 -> 4238c17dc
[SPARK-3197] [SQL] Reduce the Expression tree object creations for aggregation
function (min/max)
Aggregation function min/max in catalyst will create expression tree for each
single row, however, the expression tree creation is quite expensive in a
multithreading env currently. Hence we got a very bad performance for the
min/max.
Here is the benchmark that I've done in my local.
Master | Previous Result (ms) | Current Result (ms)
------------ | ------------- | -------------
local | 3645 | 3416
local[6] | 3602 | 1002
The Benchmark source code.
```
case class Record(key: Int, value: Int)
object TestHive2 extends HiveContext(new SparkContext("local[6]",
"TestSQLContext", new SparkConf()))
object DataPrepare extends App {
import TestHive2._
val rdd = sparkContext.parallelize((1 to 10000000).map(i => Record(i % 3000,
i)), 12)
runSqlHive("SHOW TABLES")
runSqlHive("DROP TABLE if exists a")
runSqlHive("DROP TABLE if exists result")
rdd.registerAsTable("records")
runSqlHive("""CREATE TABLE a (key INT, value INT)
| ROW FORMAT SERDE
|
'org.apache.hadoop.hive.serde2.columnar.LazyBinaryColumnarSerDe'
| STORED AS RCFILE
""".stripMargin)
runSqlHive("""CREATE TABLE result (key INT, value INT)
| ROW FORMAT SERDE
|
'org.apache.hadoop.hive.serde2.columnar.LazyBinaryColumnarSerDe'
| STORED AS RCFILE
""".stripMargin)
hql(s"""from records
| insert into table a
| select key, value
""".stripMargin)
}
object PerformanceTest extends App {
import TestHive2._
hql("SHOW TABLES")
hql("set spark.sql.shuffle.partitions=12")
val cmd = "select min(value), max(value) from a group by key"
val results = ("Result1", benchmark(cmd)) ::
("Result2", benchmark(cmd)) ::
("Result3", benchmark(cmd)) :: Nil
results.foreach { case (prompt, result) => {
println(s"$prompt: took ${result._1} ms (${result._2} records)")
}
}
def benchmark(cmd: String) = {
val begin = System.currentTimeMillis()
val count = hql(cmd).count
val end = System.currentTimeMillis()
((end - begin), count)
}
}
```
Author: Cheng Hao <[email protected]>
Closes #2113 from chenghao-intel/aggregation_expression_optimization and
squashes the following commits:
db40395 [Cheng Hao] remove the transient and add val for the expression property
d56167d [Cheng Hao] Reduce the Expressions creation
Project: http://git-wip-us.apache.org/repos/asf/spark/repo
Commit: http://git-wip-us.apache.org/repos/asf/spark/commit/4238c17d
Tree: http://git-wip-us.apache.org/repos/asf/spark/tree/4238c17d
Diff: http://git-wip-us.apache.org/repos/asf/spark/diff/4238c17d
Branch: refs/heads/master
Commit: 4238c17dc9e1f2f93cc9e6c768f92bd27bf1df66
Parents: 3b5eb70
Author: Cheng Hao <[email protected]>
Authored: Wed Aug 27 12:50:47 2014 -0700
Committer: Michael Armbrust <[email protected]>
Committed: Wed Aug 27 12:50:47 2014 -0700
----------------------------------------------------------------------
.../sql/catalyst/expressions/aggregates.scala | 30 +++++++++++---------
.../sql/catalyst/expressions/literals.scala | 5 ++--
2 files changed, 18 insertions(+), 17 deletions(-)
----------------------------------------------------------------------
http://git-wip-us.apache.org/repos/asf/spark/blob/4238c17d/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
----------------------------------------------------------------------
diff --git
a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
index dbc0c29..15560a2 100644
---
a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
+++
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
@@ -105,17 +105,18 @@ case class Min(child: Expression) extends
PartialAggregate with trees.UnaryNode[
case class MinFunction(expr: Expression, base: AggregateExpression) extends
AggregateFunction {
def this() = this(null, null) // Required for serialization.
- var currentMin: Any = _
+ val currentMin: MutableLiteral = MutableLiteral(null, expr.dataType)
+ val cmp = GreaterThan(currentMin, expr)
override def update(input: Row): Unit = {
- if (currentMin == null) {
- currentMin = expr.eval(input)
- } else if(GreaterThan(Literal(currentMin, expr.dataType),
expr).eval(input) == true) {
- currentMin = expr.eval(input)
+ if (currentMin.value == null) {
+ currentMin.value = expr.eval(input)
+ } else if(cmp.eval(input) == true) {
+ currentMin.value = expr.eval(input)
}
}
- override def eval(input: Row): Any = currentMin
+ override def eval(input: Row): Any = currentMin.value
}
case class Max(child: Expression) extends PartialAggregate with
trees.UnaryNode[Expression] {
@@ -135,17 +136,18 @@ case class Max(child: Expression) extends
PartialAggregate with trees.UnaryNode[
case class MaxFunction(expr: Expression, base: AggregateExpression) extends
AggregateFunction {
def this() = this(null, null) // Required for serialization.
- var currentMax: Any = _
+ val currentMax: MutableLiteral = MutableLiteral(null, expr.dataType)
+ val cmp = LessThan(currentMax, expr)
override def update(input: Row): Unit = {
- if (currentMax == null) {
- currentMax = expr.eval(input)
- } else if(LessThan(Literal(currentMax, expr.dataType), expr).eval(input)
== true) {
- currentMax = expr.eval(input)
+ if (currentMax.value == null) {
+ currentMax.value = expr.eval(input)
+ } else if(cmp.eval(input) == true) {
+ currentMax.value = expr.eval(input)
}
}
- override def eval(input: Row): Any = currentMax
+ override def eval(input: Row): Any = currentMax.value
}
case class Count(child: Expression) extends PartialAggregate with
trees.UnaryNode[Expression] {
@@ -350,7 +352,7 @@ case class AverageFunction(expr: Expression, base:
AggregateExpression)
private val zero = Cast(Literal(0), expr.dataType)
private var count: Long = _
- private val sum = MutableLiteral(zero.eval(EmptyRow))
+ private val sum = MutableLiteral(zero.eval(null), expr.dataType)
private val sumAsDouble = Cast(sum, DoubleType)
private def addFunction(value: Any) = Add(sum, Literal(value))
@@ -423,7 +425,7 @@ case class SumFunction(expr: Expression, base:
AggregateExpression) extends Aggr
private val zero = Cast(Literal(0), expr.dataType)
- private val sum = MutableLiteral(zero.eval(null))
+ private val sum = MutableLiteral(zero.eval(null), expr.dataType)
private val addFunction = Add(sum, Coalesce(Seq(expr, zero)))
http://git-wip-us.apache.org/repos/asf/spark/blob/4238c17d/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
----------------------------------------------------------------------
diff --git
a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
index a8c2396..78a0c55 100644
---
a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
+++
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
@@ -61,11 +61,10 @@ case class Literal(value: Any, dataType: DataType) extends
LeafExpression {
}
// TODO: Specialize
-case class MutableLiteral(var value: Any, nullable: Boolean = true) extends
LeafExpression {
+case class MutableLiteral(var value: Any, dataType: DataType, nullable:
Boolean = true)
+ extends LeafExpression {
type EvaluatedType = Any
- val dataType = Literal(value).dataType
-
def update(expression: Expression, input: Row) = {
value = expression.eval(input)
}
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