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https://issues.apache.org/jira/browse/SPARK-37646?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Shixiong Zhu reassigned SPARK-37646:
------------------------------------
Assignee: Shixiong Zhu
> Avoid touching Scala reflection APIs in the lit function
> --------------------------------------------------------
>
> Key: SPARK-37646
> URL: https://issues.apache.org/jira/browse/SPARK-37646
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.2.0
> Reporter: Shixiong Zhu
> Assignee: Shixiong Zhu
> Priority: Major
>
> Currently lit is slow when the concurrency is high as it needs to hit the
> Scala reflection code which hits global locks. For example, running the
> following test locally using Spark 3.2 shows the difference:
> {code:java}
> scala> :paste
> // Entering paste mode (ctrl-D to finish)import
> org.apache.spark.sql.functions._
> import org.apache.spark.sql.Column
> import org.apache.spark.sql.catalyst.expressions.Literalval parallelism =
> 50def testLiteral(): Unit = {
> val ts = for (_ <- 0 until parallelism) yield {
> new Thread() {
> override def run() {
> for (_ <- 0 until 50) {
> new Column(Literal(0L))
> }
> }
> }
> }
> ts.foreach(_.start())
> ts.foreach(_.join())
> }def testLit(): Unit = {
> val ts = for (_ <- 0 until parallelism) yield {
> new Thread() {
> override def run() {
> for (_ <- 0 until 50) {
> lit(0L)
> }
> }
> }
> }
> ts.foreach(_.start())
> ts.foreach(_.join())
> }println("warmup")
> testLiteral()
> testLit()println("lit: false")
> spark.time {
> testLiteral()
> }
> println("lit: true")
> spark.time {
> testLit()
> }// Exiting paste mode, now interpreting.warmup
> lit: false
> Time taken: 8 ms
> lit: true
> Time taken: 682 ms
> import org.apache.spark.sql.functions._
> import org.apache.spark.sql.Column
> import org.apache.spark.sql.catalyst.expressions.Literal
> parallelism: Int = 50
> testLiteral: ()Unit
> testLit: ()Unit {code}
>
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