[SPARK-21603][SQL]The wholestage codegen will be much slower then that is closed when the function is too long

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeFormatter.scala

@@ -89,6 +89,14 @@ object CodeFormatter {
     }
     new CodeAndComment(code.result().trim(), map)
   }
+
+  def stripExtraNewLinesAndComments(input: String): String = {
+    val commentReg =
+      ("""([ |\t]*?\/\*[\s|\S]*?\*\/[ |\t]*?)|""" +   // strip /*comment*/
+        """([ |\t]*?\/\/[\s\S]*?\n)""").r               // strip //comment
+    val codeWithoutComment = commentReg.replaceAllIn(input, "")
+    codeWithoutComment.replaceAll("""\n\s*\n""", "\n")          // strip ExtraNewLines
+  }
 }
 
 private class CodeFormatter {

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeGenerator.scala

@@ -355,6 +355,20 @@ class CodegenContext {
    */
   private val placeHolderToComments = new mutable.HashMap[String, String]
 
+  /**
+   * It will count the lines of every Java function generated by whole-stage codegen,
+   * if there is a function of length greater than spark.sql.codegen.maxLinesPerFunction,
+   * it will return true.
+   */
+  def isTooLongGeneratedFunction: Boolean = {
+    classFunctions.values.exists { _.values.exists {
+      code =>
+        val codeWithoutComments = CodeFormatter.stripExtraNewLinesAndComments(code)
+        codeWithoutComments.count(_ == '\n') > SQLConf.get.maxLinesPerFunction
+      }
+    }
+  }
+
   /**
    * Returns a term name that is unique within this instance of a `CodegenContext`.
    */

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -572,6 +572,14 @@ object SQLConf {
       "disable logging or -1 to apply no limit.")
     .createWithDefault(1000)
 
+  val WHOLESTAGE_MAX_LINES_PER_FUNCTION = buildConf("spark.sql.codegen.maxLinesPerFunction")
+    .internal()
+    .doc("The maximum lines of a single Java function generated by whole-stage codegen. " +
+      "When the generated function exceeds this threshold, " +
+      "the whole-stage codegen is deactivated for this subtree of the current query plan.")
+    .intConf
+    .createWithDefault(1500)
+
   val FILES_MAX_PARTITION_BYTES = buildConf("spark.sql.files.maxPartitionBytes")
     .doc("The maximum number of bytes to pack into a single partition when reading files.")
     .longConf
@@ -1014,6 +1022,8 @@ class SQLConf extends Serializable with Logging {
 
   def loggingMaxLinesForCodegen: Int = getConf(CODEGEN_LOGGING_MAX_LINES)
 
+  def maxLinesPerFunction: Int = getConf(WHOLESTAGE_MAX_LINES_PER_FUNCTION)
+
   def tableRelationCacheSize: Int =
     getConf(StaticSQLConf.FILESOURCE_TABLE_RELATION_CACHE_SIZE)
 

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeFormatterSuite.scala

@@ -53,6 +53,38 @@ class CodeFormatterSuite extends SparkFunSuite {
     assert(reducedCode.body === "/*project_c4*/")
   }
 
+  test("removing extra new lines and comments") {
+    val code =
+      """
+        |/*
+        |  * multi
+        |  * line
+        |  * comments
+        |  */
+        |
+        |public function() {
+        |/*comment*/
+        |  /*comment_with_space*/
+        |code_body
+        |//comment
+        |code_body
+        |  //comment_with_space
+        |
+        |code_body
+        |}
+      """.stripMargin
+
+    val reducedCode = CodeFormatter.stripExtraNewLinesAndComments(code)
+    assert(reducedCode ===
+      """
+        |public function() {
+        |code_body
+        |code_body
+        |code_body
+        |}
+      """.stripMargin)
+  }
+
   testCase("basic example") {
     """
       |class A {

sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegenExec.scala

@@ -370,6 +370,14 @@ case class WholeStageCodegenExec(child: SparkPlan) extends UnaryExecNode with Co
 
   override def doExecute(): RDD[InternalRow] = {
     val (ctx, cleanedSource) = doCodeGen()
+    if (ctx.isTooLongGeneratedFunction) {
+      logWarning("Found too long generated codes and JIT optimization might not work, " +
+        "Whole-stage codegen disabled for this plan, " +
+        "You can change the config spark.sql.codegen.MaxFunctionLength " +
+        "to adjust the function length limit:\n "
+        + s"$treeString")
+      return child.execute()
+    }
     // try to compile and fallback if it failed
     try {
       CodeGenerator.compile(cleanedSource)

sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/AggregateBenchmark.scala

@@ -301,6 +301,68 @@ class AggregateBenchmark extends BenchmarkBase {
     */
   }
 
+  ignore("max function length of wholestagecodegen") {
+    val N = 20 << 15
+
+    val benchmark = new Benchmark("max function length of wholestagecodegen", N)
+    def f(): Unit = sparkSession.range(N)
+      .selectExpr(
+        "id",
+        "(id & 1023) as k1",
+        "cast(id & 1023 as double) as k2",
+        "cast(id & 1023 as int) as k3",
+        "case when id > 100 and id <= 200 then 1 else 0 end as v1",
+        "case when id > 200 and id <= 300 then 1 else 0 end as v2",
+        "case when id > 300 and id <= 400 then 1 else 0 end as v3",
+        "case when id > 400 and id <= 500 then 1 else 0 end as v4",
+        "case when id > 500 and id <= 600 then 1 else 0 end as v5",
+        "case when id > 600 and id <= 700 then 1 else 0 end as v6",
+        "case when id > 700 and id <= 800 then 1 else 0 end as v7",
+        "case when id > 800 and id <= 900 then 1 else 0 end as v8",
+        "case when id > 900 and id <= 1000 then 1 else 0 end as v9",
+        "case when id > 1000 and id <= 1100 then 1 else 0 end as v10",
+        "case when id > 1100 and id <= 1200 then 1 else 0 end as v11",
+        "case when id > 1200 and id <= 1300 then 1 else 0 end as v12",
+        "case when id > 1300 and id <= 1400 then 1 else 0 end as v13",
+        "case when id > 1400 and id <= 1500 then 1 else 0 end as v14",
+        "case when id > 1500 and id <= 1600 then 1 else 0 end as v15",
+        "case when id > 1600 and id <= 1700 then 1 else 0 end as v16",
+        "case when id > 1700 and id <= 1800 then 1 else 0 end as v17",
+        "case when id > 1800 and id <= 1900 then 1 else 0 end as v18")
+      .groupBy("k1", "k2", "k3")
+      .sum()
+      .collect()
+
+    benchmark.addCase(s"codegen = F") { iter =>
+      sparkSession.conf.set("spark.sql.codegen.wholeStage", "false")
+      f()
+    }
+
+    benchmark.addCase(s"codegen = T maxLinesPerFunction = 10000") { iter =>
+      sparkSession.conf.set("spark.sql.codegen.wholeStage", "true")
+      sparkSession.conf.set("spark.sql.codegen.maxLinesPerFunction", "10000")
+      f()
+    }
+
+    benchmark.addCase(s"codegen = T maxLinesPerFunction = 1500") { iter =>
+      sparkSession.conf.set("spark.sql.codegen.wholeStage", "true")
+      sparkSession.conf.set("spark.sql.codegen.maxLinesPerFunction", "1500")
+      f()
+    }
+
+    benchmark.run()
+
+    /*
+    Java HotSpot(TM) 64-Bit Server VM 1.8.0_111-b14 on Windows 7 6.1
+    Intel64 Family 6 Model 58 Stepping 9, GenuineIntel
+    max function length of wholestagecodegen: Best/Avg Time(ms)    Rate(M/s)   Per Row(ns) Relative
+    ----------------------------------------------------------------------------------------------
+    codegen = F                                    462 /  533          1.4         704.4     1.0X
+    codegen = T maxLinesPerFunction = 10000       3444 / 3447          0.2        5255.3     0.1X
+    codegen = T maxLinesPerFunction = 1500         447 /  478          1.5         682.1     1.0X
+     */
+  }
+
 
   ignore("cube") {
     val N = 5 << 20